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{{Short description|Toilet that uses water to convey human waste down a pipe}}
{{Redirect|W/C|other uses|WC (disambiguation){{!}}WC}}
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| alt1              = Close coupled [[cistern]] type flushing toilet.
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| alt2              = Porcelain squat toilet, with water tank for flushing ([[Wuhan, China]])
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| footer            = Flush toilets with [[cistern]]s{{break}} Top: A sit toilet{{break}}Bottom: A [[squat toilet]]
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A '''flush toilet''' (also known as a '''flushing toilet''', '''water closet''' ('''WC'''); see also [[Toilet#Names|toilet names]]) is a [[toilet]] that disposes of [[human waste]] (i.e., [[urine]] and [[Human feces|feces]]) by collecting it in a bowl and then using the force of water to channel it ("flush" it) through a [[wikt:drainpipe|drainpipe]] to another location for treatment, either [[Septic system|nearby]] or at a [[Waste water treatment plants|communal facility]]. Flush toilets can be designed for sitting or [[Squat toilet|squatting]] (often regionally differentiated). Most modern [[sewage]] treatment systems are also designed to process specially designed [[toilet paper]], and there is increasing interest for flushable [[Wet wipe|wet wipes]]. [[Porcelain]] (sometimes with [[vitreous china]]) is a popular material for these toilets, although public or institutional ones may be metal, etc.

Flush toilets are a type of [[plumbing fixture]], and usually incorporate a bend called a [[Trap (plumbing)|''trap'']] (S-, U-, J-, or P-shaped) that causes water to collect in the toilet bowl – to hold the waste and act as a seal against noxious [[sewer gas]]es. Urban and suburban flush toilets are connected to a [[sewerage]] system that conveys [[wastewater]] to a [[sewage treatment plant]]; rurally, a [[septic tank]] or composting system is mostly used.<ref>Kagan, Mya. "Where Does the Water Go When I Flush the Toilet?" Kids' Why Questions. Whyzz. Publications LLC, 2011.</ref>

The opposite of a flush toilet is a [[dry toilet]], which uses no water for flushing. Associated devices are [[urinal]]s, which primarily dispose of urine, and [[bidet]]s, which use water to cleanse the [[Human anus|anus]], [[perineum]], and [[vulva]] after using the toilet. 

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==Operation==
[[File:Flushing toilet.jpg|thumb|upright|A flush toilet bowl during flushing action]]
[[File:Toilettenspülung 01.ogg|thumb|Typical sound of a flush toilet]]

A typical flush toilet is a fixed, vitreous [[ceramic]] bowl (also known as a pan) which is connected to a drain. After use, the bowl is emptied and cleaned by the rapid flow of water into the bowl. This flush may flow from a dedicated tank (cistern), a high-pressure water pipe controlled by a flush valve, or by manually pouring water into the bowl. Tanks and valves are normally operated by the user, by pressing a button, pushing down on a handle, pulling a lever or pulling a chain. The water is directed around the bowl by a molded flushing rim around the top of the bowl or by one or more jets, so that the entire internal surface of the bowl is rinsed with water.

===Mechanical flush from a cistern===
A typical toilet has a tank fixed above the bowl which contains a fixed volume of water, and two devices. The first device allows part of the contents of the tank (usually in the {{convert|3|-|6|L|USgal|abbr=in|disp=or|frac=4}} range) to be discharged rapidly into the toilet bowl, causing the contents of the bowl to be swept or sucked out of the toilet and into the drain, when the user operates the flush. The second device automatically allows water to enter the tank until the water level is appropriate for a flush.

The water may be discharged through a "toilet flapper valve" (not to be confused with a type of [[check valve]]), or through a [[siphon]]. A [[Float (liquid level)|float]] usually controls the refilling device.

=== Mechanical flush from a high-pressure water supply ===
Toilets without cisterns are often flushed through a simple flush valve or "Flushometer" connected directly to the water supply. These are designed to rapidly discharge a limited volume of water when the lever or button is pressed then released.

===Manual flush (pour flush)===

A toilet does not need be connected to a water supply, but may be pour-flushed.<ref name="tilley">{{cite book|url=http://www.eawag.ch/en/department/sandec/publications/compendium/|title=Compendium of Sanitation Systems and Technologies|last2=Ulrich|first2=Lukas|last3=Lüthi|first3=Christoph|last4=Reymond|first4=Philippe|last5=Zurbrügg|first5=Chris|publisher=Swiss Federal Institute of Aquatic Science and Technology (Eawag)|isbn=978-3-906484-57-0|edition=2nd|location=Duebendorf, Switzerland|last1=Tilley|first1=Elizabeth|year=2014}}</ref> This type of flush toilet has no cistern or permanent water supply, but is flushed by pouring in a few litres of water from a container. The flushing can use as little as {{convert|2|–|3|L|USgal|abbr=in|frac=4}}.<ref name="tilley" /> This type of toilet is common in many Asian countries. The toilet can be connected to one or two pits, in which case it is called a "pour flush [[pit latrine]]" or a "twin pit pour flush pit latrine". It can also be connected to a [[septic tank]].

===Vacuum toilet===
[[File:Vacuum toilet in a train.jpg|thumb|upright|Vacuum toilet in a train in Switzerland]]
A vacuum toilet is a flush toilet that is connected to a [[Vacuum sewer|vacuum sewer system]], and removes waste by suction. They may use very little water (less than {{convert|1/4|L|USgal|spell=in|disp=or|frac=16}} per flush) or none.<ref name=wisegeek>{{cite web |title=What are Vacuum Toilets?|url=https://www.wisegeek.com/what-are-vacuum-toilets.htm |website=wiseGEEK|date=26 December 2023 }}</ref> Some flush with coloured disinfectant solution rather than with water.{{citation needed|date=November 2019}} They may be used to separate [[Blackwater (waste)|blackwater]] and [[greywater]], and process them separately{{citation needed|date=November 2019}} (for instance, the fairly dry blackwater can be used for [[biogas]] production, or in a [[composting toilet]]).

[[Passenger train toilets]], [[Aircraft lavatory|aircraft lavatories]], bus toilets, and ships with plumbing often use vacuum toilets. The lower water usage saves weight and avoids water slopping out of the toilet bowl in motion.<ref>{{cite web |title=How does the toilet in a commercial airliner work? |url=https://science.howstuffworks.com/transport/flight/modern/question314.htm |website=HowStuffWorks |language=en |date=1 April 2000}}</ref> Aboard vehicles, a portable collection chamber is used; if it is filled by positive pressure from an intermediate vacuum chamber, it need not be kept under vacuum.{{citation needed|date=November 2019}}

==Flushing systems==
The flushing system provides a large flow of water into the bowl. They normally take the form of either fixed tanks of water or flush valves.

=== Flush tanks ===
Flush tanks or cisterns usually incorporate a mechanism to release water from the tank and an automatic valve to allow the cistern to be refilled automatically.

This system is suitable for locations plumbed with {{convert|1/2|or|3/8|in|mm|abbr=in|order=flip}} water pipes which cannot supply water quickly enough to flush the toilet; the tank is needed to supply a large volume of water in a short time. The tank typically collects between {{convert|6|and|17|L|USgal|abbr=in}} of water over a period of time. In modern installations the storage tank is usually mounted directly above and behind the bowl.

Older installations, known as "high suite combinations", used a high-level cistern (tank), fitted above head height, activated by a [[pull chain]] connected to a flush lever on the cistern. When more modern close-coupled cistern and bowl combinations were first introduced, these were first referred to as "low suite combinations". Modern versions have a neater-looking low-level cistern with a lever that the user can reach directly, or a close-coupled cistern that is even lower down and fixed directly to the bowl. In recent decades{{when?|date=April 2024}} the close coupled tank–bowl combination has become the most popular residential system, as it has been found by ceramic engineers that improved waterway design is a more effective way to enhance the bowl's flushing action than high tank mounting.

====Tank fill valve====
[[File:Ballcock.svg|thumb|right|The ballcock or float valve is often used to regulate the filling of a tank or cistern. When the fluid level drops, the float descends, levering the valve opening and allowing more fluid to enter. Once the float reaches the 'full' position, the arm presses the valve shut again.|219x219px]]
Tank fill [[valves]] are found in all tank-style toilets. The valves are of two main designs: the side-float design and the concentric-float design. The side-float design has existed for over a hundred years. The concentric design has only existed since 1957 but is gradually becoming more popular than the side-float design.

The side-float design uses a float on the end of a lever to control the fill valve. The float is usually shaped like a ball, so the mechanism is often called a ball-valve or a [[ballcock]] (cock in this context is an alternative term for valve; see, for example, [[stopcock]]). Historically floats were made from copper sheet, but are now usually plastic. The float is located to one side of the main valve tower or inlet at the end of a rod or arm. As the float rises, so does the float-arm. The arm connects to the fill valve that shuts off the inflow of water when the float reaches a level at which the volume of water in the tank is sufficient to provide another flush.<!-- should mention fill valve uses hysteresis -->

[[File:Concentric Float Valve.svg|alt=Concentric Float Valve|thumb|left|One type of concentric float valve. The concentric float valve opens when the fluid level is low, allowing more fluid to enter [Figure 1]. When the fluid level returns to the full level, the valve is shut [Figure 2].|220x220px]]
The newer concentric-float fill valve consists of a tower which is encircled by a plastic float assembly. Operation is otherwise the same as a side-float fill valve, even though the float position is somewhat different. By virtue of its more compact layout, interference between the float and other obstacles (tank insulation, flush valve, and so on) is greatly reduced, thus increasing reliability. The concentric-float fill valve is also designed to signal to users automatically when there is a leak in the tank, by making much more noise when a leak is present than the older style side-float fill valve, which tends to be nearly silent when a slow leak is present.

Newer fill valves have a delayed action that will not start filling the tank/cistern until the flapper/drop valve has closed which saves some water.

====Flapper-flush valve or drop valve====

In tanks using a flapper-flush valve, the outlet at the bottom of the tank is covered by a buoyant (plastic or rubber) cover, or flapper, which is held in place against a fitting (the ''flush valve seat'') by water pressure. The user pushes a lever to flush the toilet, which lifts the flush valve from the valve seat. The valve then floats clear of the seat, allowing the tank to empty quickly into the bowl. As the water level drops, the floating flush valve descends back to the bottom of the tank and covers the outlet pipe again. This system is common in homes in North America and in continental Europe. From 2001, due to a change in regulations, this flush system has also become available in the UK, where prior to that the siphon-type flush was mandated.<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/uk/696115.stm|title=Is the British loo down the pan?|work=BBC News|access-date=27 May 2018}}</ref><ref>{{Cite web|url=http://www.legislation.gov.uk/uksi/1999/1148/schedule/2/made|title=The Water Supply (Water Fittings) Regulations 1999|website=www.legislation.gov.uk|language=en|access-date=27 May 2018}}</ref>

[[Dual flush toilet|Dual flush]] versions of this design with push buttons are widely available. They have one level of water for [[urine|liquid waste]] and a higher level for [[solid waste]].

In North America, newer toilets have a {{cvt|3|in|mm}} flapper-flush valve. Older toilets have a {{cvt|2|in|mm}} flapper-flush valve.<ref>{{Cite web|url=https://www.korky.com/toilet-help/troubleshooting-guide/what-size-flapper-do-i-need|title=What Toilet Flapper Size Do I Need?|website=www.korky.com}}</ref> The larger flapper-flush valve is used on toilets that use less water, such as {{cvt|1.6|USgal|L}} per flush. Some have a bell inlet for a faster more effective flush.

A problem with the valve type flush mechanism is that it invariably starts to leak after a couple of years use due to wear and tear of the valve, particles, etc. trapped in the valve. Quite often this leakage is barely noticeable but adds up to a considerable water wastage. In the UK it has been found that between 5 and 8% of toilets (mostly dual flush drop valves) are leaking, each one between {{convert|215|and|400|L|USgal|abbr=in}} on average per day.<ref>{{Cite web|url=https://www.waterwise.org.uk/knowledge-base/leaky-loo-position-statement-october-2020/|title=Waterwise Leaky Loo Position Statement (October 2020)|website=www.waterwise.org.uk}}</ref> Whilst they save more water than they leak, regular maintenance or use of a non-leaking flush mechanism will maximise water savings.

====Siphon-flush mechanism====
[[File:Siphonic WC cistern.svg|alt=Diagram of a siphonic WC cistern|left|thumb|A simplified diagram of a siphonic WC cistern. The siphon is formed of a vertical pipe (1) that links the flush pipe (2) to a domed chamber (3). A perforated disc (4) covered by a flexible plate or flap (5) is joined by the siphon rod (6) to the flush lever (7).]]
This system, invented by Albert Giblin and common in the [[United Kingdom|UK]], uses a storage tank similar to that used in the flapper-flush-valve system above.<ref>{{Cite book|url={{GBurl|id=JWLeCwAAQBAJ}}|title=Supply Chain in the Pharmaceutical Industry: Strategic Influences and Supply Chain Responses|first=Rob |last=Whewell|publisher=CRC Press|year=2016|isbn=978-1-317-04833-6|via=[[Google Books]]}}</ref> This flush valve system is sometimes referred to as a ''valveless'' system, since no valve as such is required.

The siphon is formed of a vertical pipe that links the flush pipe to a domed chamber inside the cistern. A perforated disc, covered by a flexible plate or flap, is fitted inside this chamber and is joined by a rod to the flush lever.

Pressing the lever raises the disc, forces water over the top of the siphon into the vertical pipe, and starts the siphonic flow. Water flows through the perforated disc past the flap until the cistern is empty, at which point air enters the siphon and the flush stops.

The advantage of a siphon over the flush valve is that it has no sealing [[Washer (mechanical)|washers]] that can wear out and cause leaks, whereas other valve types - flapper, drop valve do leak, invariably after a couple of years of use and they have reduced water savings due to the valves not being maintained in practice. The siphon membrane will require occasional replacement.

Until 1 January 2001, the use of siphon-type cisterns was mandatory in the UK<ref>{{Cite web|url=http://www.legislation.gov.uk/uksi/1999/1148/schedule/2/made|title=The Water Supply (Water Fittings) Regulations 1999|website=www.legislation.gov.uk|language=en|access-date=29 September 2020}}</ref> but after that date the regulations additionally allowed pressure flushing cisterns and pressure flushing valves (though the latter remained forbidden in houses). Siphons can sometimes be more difficult to operate than a "flapper"-based flush valve because moving the lever requires more torque than a flapper system. This additional torque is required because a certain amount of water must be lifted up into the siphon passageway in order to initiate the siphon action in the tank. Splitting or jamming of the flexible flap covering the perforated disc can cause the cistern to stop working.

Dual-flush versions of the siphon cistern provide a shorter flush option by allowing air into the siphon to stop the siphon action before the tank is empty.

The siphon system can also be combined with an air box to allow multiple siphons to be installed in a single [[Flushing trough|trough cistern]].

====High-pressure or pressure-assisted tanks====
[[File:Old toilet with elevated cistern and chain.jpg|thumbnail|upright|An elevated cistern produces a high-pressure flush using [[hydrostatic pressure]].]]
[[File:Sloan pressure vessel from a Gerber Powerflush toilet.png|thumbnail|left|Sloan pressure vessel]]
Pressure-assisted toilets are sometimes found in both private (single, multiple, and lodging) installations as well as light commercial installations (such as offices). Products from several companies use {{convert|1.4|to|1.0|gal|L|round=0.5|abbr=in|order=flip}} per flush.

The mechanism consists of a plastic tank hidden inside the typical ceramic cistern or an exposed metal tank/cistern.<ref>{{Cite web|url=http://www.griffon.fr/griffon-ancien-site/wp-content/uploads/2020/01/Notice-hydrochasse-20200101.pdf/|title=Griffon hydrochasse - pressure tank/cistern|date=|website=www.griffon.fr|language=fr|access-date=26 June 2021|archive-date=9 May 2021|archive-url=https://web.archive.org/web/20210509153920/https://www.griffon.fr/griffon-ancien-site/wp-content/uploads/2020/01/Notice-hydrochasse-20200101.pdf|url-status=dead}}</ref>
When the tank fills with water, the air trapped inside compresses. When the air pressure inside the plastic tank reaches a certain level, the tank stops filling with water. A high-pressure valve located in the center of the vessel holds the air and water inside until the user flushes the toilet.<ref>{{Cite web|url=https://www.pmengineer.com/articles/87275-pressure-assist-technology-how-it-works-where-it-s-used|title=Pressure-Assist Technology: How It Works, Where It's Used|website=www.pmengineer.com|language=en|access-date=4 January 2019}}</ref>

During flushing, the user activates the valve via a button or lever, which releases the pressurized water into the bowl at a flow rate much higher than a conventional gravity-flow toilet. One advantage to this is lower water consumption than a gravity-flow toilet, or more effectiveness with a similar amount of water. As a result, the toilet does not clog as easily as those using non-pressurized mechanisms.

However, there are some financial and safety disadvantages. These toilets are generally more expensive to purchase, and the plastic tanks need to be replaced about every 10 years. They also have a noisier flush than other models. In addition, pressure-assisted tanks have been known to explode, causing serious injuries and property damage, resulting in a massive recall beginning in 2012 of over 1.4 million toilets equipped with the tank.<ref>{{Cite web|url=https://kfor.com/2014/05/21/exploding-toilet-warning-flushmate-recall-after-toilets-blow-users-out-of-water/|title=Exploding Toilet Warning: Flushmate recall after toilets blow users out of water|date=21 May 2014|website=KFOR.com|language=en|access-date=4 January 2019}}</ref><ref>{{Cite web|url=http://www.nbcnewyork.com/news/national-international/Flushmate-Toilet-Flushing-System-Bursting-Recall-498196751.html|title=Toilet Flushing System Burst Danger Prompts Massive Recall|website=NBC New York|date=22 October 2018 |language=en|access-date=4 January 2019}}</ref>

Some newer toilets use similar pressure-assist technology, along with a bowl and trapway designed to enhance the siphon effect; they use only {{convert|0.8|USgal|L|abbr=in|order=flip}} per flush, or {{convert|0.5|USgal|L|abbr=in|order=flip}} / {{convert|0.95|USgal|L|abbr=in|order=flip}} for dual flush models.<ref>{{Cite news|url=http://www.pmengineer.com/articles/84237-point-counterpoint-pressure-assist-vs-gravity-activation-toilets|title=Point/Counterpoint: Pressure-Assist vs. Gravity Activation Toilets|access-date=6 April 2017|language=en}}</ref> This design is also much quieter than other pressure-assist or flushometer toilets.

====Tipping bucket type valve====
A number of tipping bucket type cisterns have been developed.<ref>{{Cite web|url=http://www.waterflush.fr/en/|title=EcoNeves Waterflush cistern (Tip Bucket)|website=www.waterflush.fr/en/|language=en|access-date=26 June 2021}}</ref> In the cistern is placed a tipping bucket with its axis aligned or perpendicular with the cistern. They have a lever which is rotated emptying the bucket which allows a variable flush. Usually the quantity of water is marked on the cistern and depending on the performance of the bowl a dual flush can be achieved e.g. {{cvt|3/6|L|USgal}}, {{frac|3|4.5}}&nbsp;L&nbsp;({{cvt|2/3|L|USgal|disp=out}}), {{cvt|3/3|L|USgal}}, {{cvt|1/2|L|USgal}}, etc. A normal or delayed action refill valve is used.

===Tankless style with high-pressure (flushometer) valve===
{{Main|Flushometer}}
In 1906, [[William Elvis Sloan|William Sloan]] first made available his "flushometer" style toilet flush valve, incorporating his patented design.<ref>{{cite patent
 |inventor-first= William
 |inventor-last= Sloan
 |inventorlink= William Elvis Sloan
 |title= Valve
 |fdate= 1906-06-13
 |pubdate= 1910-12-06
 |country= US
 |number= 977562
}}</ref> The design proved to be very popular and efficient and remains so to this day. Flushometer toilet flush valves are still often installed in commercial restrooms, and are frequently used for both toilets and urinals. Since they have no tank, they have no fill delay and can be used again immediately. They can be easily identified by their distinctive chrome pipe-work, and by the absence of a toilet tank or cistern, wherever they are employed.

Some flushometer models require the user to either depress a lever or press a button, which in turn opens a flush [[valve]] allowing mains-pressure water to flow directly into the toilet bowl or urinal. Other flushometer models are electronically triggered, using an infrared sensor to initiate the flushing process. Typically, on electronically triggered models, an override button is provided in case the user wishes to manually trigger flushing earlier. Some electronically triggered models also incorporate a true mechanical manual override which can be used in the event of the failure of the electronic system. In retrofit installations, a self-contained battery-powered or hard-wired unit can be added to an existing manual flushometer to flush automatically when a user departs.

Once a flushometer valve has been flushed, and after a preset interval, the flushometer mechanism closes the valve and stops the flow. The flushometer system requires no storage tank, but uses a high rate of water flow for a very short time. Thus a 22-mm/{{frac|3|4}}-inch pipe at minimum, or preferably a 29-mm/1-inch pipe,<!-- Editor's note: Metric conversions are correct because the imperial size is the internal diameter of the pipe whereas the metric size is the external diameter. It is the same pipe.--> must be used. Water main pressures must be above {{convert|30|psi|hPa bar psi|abbr=on|order=out}}. The higher water pressure employed by a flushometer valve scours the bowl more efficiently than a gravity-driven system, and fewer blockages typically occur as a result of this higher water pressure. Flushometer systems require approximately the same amount of water as a gravity system to operate<!-- (1.6 gpf) uncommon unit defined below-->.

==Bowl design==
[[File:Four types of pedestal WC.svg|alt=Illustration of four common types of WC pan.|thumb|Four common types of WC pan: washdown (figure 1); washout (figure 2); double-trap siphonic (figure 3); single-trap siphonic with jet (figure 4).]]
{{unreferenced section|date=October 2015}}
The "bowl" or "pan" of a toilet is the receptacle that receives bodily waste. A toilet bowl is most often made of a [[ceramic]], but can sometimes be made of stainless steel or composite plastics. Toilet bowls are mounted in any one of three basic manners: above-floor mounted ([[pedestal]]), wall mounted ([[cantilever]]), or in-floor mounted ([[squat toilet]]).

Within the bowl, there are three main waterway design systems: the siphoning trapped system (found primarily in North American residential installations, and in North American light commercial installations), the non-siphoning trapped system (found in most other installations), and the valve-closet system (found in trains, passenger aircraft, buses, and other such installations around the world). Older style toilets called "washout" toilets are now only found in a few locations.

=== Siphonic bowls ===

====Single trap siphonic toilet====
[[File:Diagram of a jet-siphonic WC bowl.svg|alt=Diagram of a siphonic toilet.|left|thumb|A simplified cross-section through a siphonic toilet. The arrows show the flow of the flush water through the rim and jet into the bowl and out through the elongated S-shaped siphon.]]
The siphonic toilet, also called "siphon jet" and "siphon wash", is perhaps the most popular design in North America for residential and light commercial toilet installations. All siphonic toilets incorporate an S-shaped waterway.

Standing water in the bowl acts as a barrier to [[sewer gas]] coming out of the sewer through the drain, and also as a receptacle for waste. Sewer gas is vented through a separate vent pipe attached to the sewer line. The water in the toilet bowl is connected to the drain by a drainpipe shaped like an extended "S" which curves up behind the bowl and down to the drain. The portion of the channel behind the bowl is arranged as a [[siphon]] tube, whose length is greater than the depth of the water in the bowl. The top of the curving tube limits the height of the water in the bowl before it flows down the drain. The waterways in these toilets are designed with slightly smaller diameters than a non-siphonic toilet, so that the waterway will naturally fill up with water each time it is flushed, creating the siphon action.

At the top of the toilet bowl is a rim with many angled drain holes that are fed from the tank, which fill, rinse, and induce swirling in the bowl when it is flushed. Some designs use a large hole in the front of the rim to allow faster filling of the bowl. There may also be a siphon jet hole about {{convert|1|inch|mm|abbr=in|order=flip}} diameter in the bottom of the toilet bowl trap.

If the toilet is flushed from a tank, a large holding cistern is mounted above the toilet, containing approximately {{convert|1.2|to|1.6|USgal|L|round=0.5|abbr=in|order=flip}} of water in modern designs. This tank is built with a large drain {{convert|2|to|3|in|round=5|mm|abbr=in|order=flip}} diameter hole at its bottom covered by a flapper valve that allows the water to rapidly leave the holding tank when the flush is activated. Alternatively, water may be supplied directly via a flush valve or "flushometer".

The rapid influx of water into the bowl causes the standing water in the bowl to rise and fill the S-shaped siphon tube mounted in the back of the toilet. This starts the toilet's [[Siphon|siphonic action]]. The siphon action quickly "pulls" nearly all of the water and waste in the bowl and the on-rushing tank water down the drain in about 4–7 seconds —it flushes. When most of the water has drained out of the bowl, the continuous column of water through the siphon is broken when air enters the siphon tube. The toilet then gives its characteristic gurgle as the siphonic action ceases and no more water flows out of the toilet.

A "true siphonic toilet" can be easily identified by the noise it makes. If it can be heard to suck air down the drain at the end of a flush, then it is a true siphonic toilet. If not, then it is either a double trap siphonic or a non-siphonic toilet.

If water is poured slowly into the bowl it simply flows over the rim of the waterway and pours slowly down the drain—thus the toilet does not flush properly.

After flushing, the flapper valve in the water tank closes or the flush valve shuts; water lines and valves connected to the water supply refill the toilet tank and bowl. Then the toilet is again ready for use.

If the forward ("flush") jet connection to the upper inlet in the toilet clogs, poor or no flushing action may result. {{citation needed|date=February 2023}}

====Double trap siphonic toilet====
[[File:Double-trap siphonic WC.svg|alt=A double-trap siphonic WC.|thumb|A double-trap siphonic WC. Water enters at (A) pulling air into the aspirator (B) from the siphon leg (E) before passing into the rim (C) and into the pan (D). Water from the first trap in the bowl (F) is pushed through the siphon and out through the second trap (G) to the drain.]]
The double trap siphonic toilet is a less common type that is exceptionally quiet when flushed. A device known as an aspirator uses the flow of water in a flush to pull air from the cavity between the two traps, reducing the air pressure inside and creating a siphon which pulls water and waste from the toilet bowl. Towards the end of the flush cycle the aspirator ceases being immersed in water, thus allowing air to enter the cavity between the traps and break the siphon, without the gurgling noise, while the final flush water fills the pan.<ref name="Stacey">{{citation  |url=https://toiletreviews.info/american-standard-h2option-siphonic-toilet-review/ |title=American Standard H2Option Siphonic Toilet Review |last=Hyden |first=Stacey M. |date=17 August 2018 |publisher=Toilet Reviews |access-date=27 May 2019}}</ref>{{citation needed|date=November 2019}}

=== Non-siphonic bowls ===

==== Washdown toilet ====
Washdown toilets are the most common form of pedestal and cantilever toilets outside the Americas. {{citation needed|date=January 2020}} The bowl has a large opening at the top which tapers down to a water trap at the base. It is flushed from the top by water discharged through a flushing rim or jets. The force of the water flowing into the bowl washes the waste through the trap and into the drains.

Washdown bowls developed from earlier "hopper" closets, which were simple conical bowls connected to a drain. However, waste is typically excreted towards the back of the toilet, rather than the exact center, and the backs of the hoppers were prone to becoming soiled. The modern washdown bowl has a steeply sloping back and a more gently sloping or curving front, so the water trap is off-center, towards the rear of the toilet. With this "eccentric cone" design, most waste drops into the pool of water at the base of the bowl, rather than onto the surface of the toilet. Early washdown closets had a large water area at the base to minimize soiling, which required a large volume of water to clear them effectively. Modern bowls have a smaller area, which reduces the volume of water needed to flush them; however, that water area is always small compared to the water area of a typical North American siphonic bowl, and this makes the washdown bowl prone to soiling.

====Washout toilet====
{{Main|Reverse flush toilet}}
[[File:DE Toilette.JPG|thumb|upright|A washout toilet which holds fecal matter in a shallow depression until flushed.|alt=Washout WC]]
Washout, or ''Flachspüler'' ("shallow flush"), toilets have a flat platform with a shallow pool of water. They are flushed by a jet of water from the back that drives waste into the trap below. From there, the water flow removes it into the sewage system. An advantage of the design is that users will not get splashed from below. Taking of [[stool sample]]s is also simplified. Washout toilets have a shallow pool of water into which waste is deposited, with a trapped drain just behind this pool. Waste is cleared out from this pool of water by being swept over into the [[Trap (plumbing)|trap]] (usually either a P-trap or an S-trap) and then beyond into a sewer by water from the flush. Washout pans were among the first types of ceramic toilets invented and since the early 1970s are now only found in a decreasing number of localities in Europe.{{Citation needed|date=March 2015}} A washout toilet is a kind of flush toilet which was once predominantly used in Germany, Austria and France. It was patented in Britain by George Jennings in 1852 and remained the standard toilet type in Britain throughout the 19th century.{{Citation needed|date=August 2019}}

Examples of this type of toilet can be found in Austria, the Czech Republic, Germany, Hungary, the Netherlands, and some regions of Poland, although it is becoming less common.

One disadvantage of this design is that it may require the more intense use of a [[toilet brush]] to remove bits of feces that may have left marks on the shelf.{{Citation needed|date=December 2018}} Additionally, this design presents the disadvantage of creating a strong lingering odor since the feces are not submerged in water immediately after excretion.

==== Squat toilet ====
{{Main|Squat toilet}}
[[Image:LatrinaRoma.jpg|thumb|left|upright|Example of a [[squat toilet]] in [[Rome]], Italy]]
In many parts of Asia, people traditionally use the toilet in a [[squatting position]]. This applies to defecation and urination by males and females. Therefore, homes and public washrooms have [[squat toilet]]s, with the toilet bowl installed in the floor. This has the advantages of not needing an additional toilet seat and also being more convenient for cultures where people use water to wash their genitals instead of toilet paper. However, Western-style toilets that are mounted at sitting height and have a plastic seat have become popular as well. Many public washrooms have both squatting and sitting toilets.

In Western countries, instructions have been put up in some [[public toilet]]s used by people accustomed to squat toilets, on the correct use of a sitting-style toilet. This is to avoid breaking the toilet or seat if someone attempts to squat on the edges.<ref>{{cite news|url=https://www.bbc.co.uk/news/uk-wales-south-west-wales-16983788|title=Swansea University puts up toilet instruction posters|work=BBC News}}</ref>

The "Anglo-Indian" design used in India allows the same toilet to be used in the sitting or the squatting position.

===Valve closet===
The valve closet has a valve or flap at the exit of the bowl, often with a watertight seal to retain a pool of water in the pan. When the toilet is flushed, the valve is opened and the water in the pan flows rapidly out of the bowl into the drains, carrying the waste with it.

The earliest type of toilet, the valve closet is now rarely used for water-flush toilet systems. More complicated in design than other toilets, this design has lower reliability and is more difficult to maintain or repair. The most common use for valve closets is now in portable closets for caravans, camping, trains, and aircraft, where the flushing fluid is recycled. This design is also used in train carriages for use in areas where the waste is allowed to be simply dumped between the tracks (the flushing of such toilets is generally prohibited when the train is in a station).

Simple valve closets are used on most older style Russian trains, made in Eastern Germany ({{Not a typo|Ammendorf}} factory, design dated probably to the 1950s), employing a pan-like shutter valve at the base of the pan and discharging waste directly onto the trackbed below. Usage of this type of toilet is permitted only while the train is moving, and outside of major cities. These designs are being phased out, together with the old trains, and are being replaced with modern vacuum systems.

The British singer [[Ian Wallace (singer)|Ian Wallace]] composed and performed the humorous song "Never Do It at the Station", which mentioned the old-fashioned trackbed dumping toilets which were still in use during the mid-20th century in Britain. The song first advised frugal travelers to save money by avoiding [[pay toilet]]s in train stations, but also reminded polite passengers not to use the onboard "loo" while the train was stopped at a station.<ref name="Wallace">{{cite web|title="Never Do It At The Station" by Ian Wallace|url=http://playlists.net/artists/Ian+Wallace/track/1528744/Never+Do+It+At+The+Station|website=Playlists.net|access-date=19 May 2015}}</ref>

==Low-flow and high-efficiency flush toilets==
{{Main|Low flush toilet|Dual flush toilet}}
Since 1994, there is a significant move towards using less water for flushing toilets. This has resulted in the emergence of [[low flush toilet]] designs and local or national standards on [[water consumption]] for flushing. As an alternative some people modify an existing high flush toilet to use less water by placing a brick or water bottle into the toilet's water tank.<ref>{{cite web |url=http://www.thedailygreen.com/going-green/tips/brick-in-toilet |title=Use of brick or water bottle for water conservation |publisher=Thedailygreen.com |date=1 May 2008 |access-date=18 November 2011 |archive-date=5 February 2014 |archive-url=https://web.archive.org/web/20140205002241/http://www.thedailygreen.com/going-green/tips/brick-in-toilet |url-status=dead }}</ref> Other modifications are often done on the water system itself (such as by using [[greywater]]), or a system that pollutes the water less, for more efficient water use.

[[Urine diversion]] flush toilets, which were developed in Sweden, save water by using less water, or even no water, for the urine flush compared to about {{convert|6|L|USgal|spell=in}} the feces flush.

===US standards for new toilets===
Pre-1994 residential and pre-1997 commercial flush toilets in the United States typically used {{convert|3.4|USgal|L|0}} of water per flush (gpf or lpf). The [[United States Congress]] passed the [[Energy Policy Act of 1992]], which mandated that from 1994 common flush toilets use only {{convert|1.6|USgal|L|1}}.<ref>{{cite web|url=http://codes.lp.findlaw.com/uscode/42/77/III/A/6295 |title=42 U.S.C. sec 6295(k)(1)(A) |publisher=Codes.lp.findlaw.com |access-date=18 November 2011}}</ref> In response to the Act, manufacturers produced ''low-flow'' toilets, which many consumers did not like because they often required more than one flush to remove solids. People unhappy with the reduced performance of the low-flow toilets resorted to driving across the border to Canada or Mexico or buying [[Deconstruction (building)|salvaged]] toilets from older buildings.<ref>{{citation|url=http://www.time.com/time/magazine/article/0,9171,996507,00.html|archive-date=1 December 2008|archive-url=https://web.archive.org/web/20081201170557/http://www.time.com/time/magazine/article/0,9171,996507,00.html|title=Psst! Wanna Buy An Illegal Toilet?|first=Stacy |last=Perman|location=Windsor, Ontario|date=3 April 2000|url-status=dead|magazine=Time}}</ref> Manufacturers responded to consumers' complaints by improving the toilets. The improved products are generally identified as ''high efficiency toilets'' or HETs. HETs possess an effective flush volume of {{convert|1.3|USgal|L|1}} or less.<ref name="Veritec">{{cite web|url=http://veritec.ca |title=''Testing of Popular Toilet Models'' by Veritec Consulting |publisher=Veritec.ca |access-date=18 November 2011}}</ref> They may be ''single-flush'' or ''dual-flush''. A dual-flush toilet permits selection between different amounts of water for solid or liquid waste.<ref>[http://www.lacrossetribune.com/articles/2007/11/26/news/04toilet.txt "Low-flow revolution: As water concerns rise, toilet makers meeting the challenge"], ''Lacrosse Tribune'', 26 November 2007; accessed 3 January 2009</ref> Some HETs are [[#High-pressure or pressure-assisted tanks|''pressure-assisted'']] (or power, pump, or vacuum assisted).

The performance of a flush-toilet may be rated by a Maximum Performance (MaP) score. The low end of MaP scores is 250 (250&nbsp;grams of simulated fecal matter). The high end of MaP scores is 1,000. A toilet with a MaP score of 1,000 should provide trouble-free service. It should remove all waste with a single flush; it should not plug; it should not harbor any odor; it should be easy to keep clean. The United States [[Environmental Protection Agency]] uses a MaP score of 350 as the minimum performance threshold for HETs.<ref name="Veritec" /> 1.6 gpf toilets are also sometimes referred as Ultra Low Flow (ULF).

Methods used to make up for the inadequacies of low flow toilets include using thinner toilet paper,<ref>{{cite news|url=https://news.google.com/newspapers?id=9UxGAAAAIBAJ&pg=1262,963345|title=Mich. Congressman offers measure to flush low-flow toilet laws|first=Sandy|last=Fleishman|agency=Washington Post|newspaper=Sunday Gazette|date=5 September 1999|page=D3}}</ref> plungers, and adding extra cups of water to the bowl manually.<ref>{{cite news|url=https://www.latimes.com/archives/la-xpm-1999-jul-28-fi-60241-story.html|title=Low-Flow Toilets All Wet, Some Lawmakers Say|agency=Associated Press|newspaper=Los Angeles Times|date=28 July 1999|location=Washington}}</ref>

==Maintenance and hygiene==

===Clogging===
If clogging occurs, it is usually the result of an attempt to flush unsuitable items, or as feces size often increases with age or too much toilet paper.<ref>{{Cite book|url={{GBurl|id=AfvBaQaFtrcC}}|title=Organic Housekeeping: In Which the Non-Toxic Avenger Shows You How to Improve Your Health and That of Your Family, While You Save Time, Money, and, Perhaps, Your Sanity|last=Sandbeck|first=Ellen|date=2007|publisher=Simon and Schuster|isbn=978-1-4165-9570-0|language=en|via=Google Books}}</ref> Clogging can occur spontaneously due to [[limescale]] fouling of the drain pipe, or by overloading the stool capacity of the toilet. Stool capacity varies among toilet designs and is based on the size of the drainage pipe, the capacity of the water tank, the velocity of a flush, and the method by which the water attempts to vacate the bowl of its contents. The size and consistency of the stool is a hard-to-predict contributory factor.

In some countries, clogging has become more frequent due to regulations that require the use of small-tanked low-flush toilets in attempt to conserve water.{{citation needed|date=August 2016}} Designs which increase the velocity of flushed water or improve the travel path can improve low-flow reliability.

Partial clogging is particularly insidious, as it is usually not discovered immediately, but only later by an unsuspecting user trying to flush an incompletely emptied toilet. Overflowing of the water mixed with excrement may then occur, depending on the bowl volume, tank capacity and severity of clogging. For this reason, rooms with flush toilets may be designed as [[wet room]]s, with a second [[Floor drain|drain on the floor]], and a [[shower head]] capable of reaching the whole floor area. Common means to remedy clogging include use of a [[plunger|toilet plunger]], [[drain cleaner]], or a [[plumber's snake]].

===Aerosols===
{{Main|Toilet plume}}
A "toilet [[Plume (fluid dynamics)|plume]]" is the dispersal of microscopic particles into the air as a result of flushing a toilet. Normal use of a toilet by healthy people is considered unlikely to be a major health risk.<ref name=":12">{{Cite journal|last1=Barker|first1=J.|last2=Jones|first2=M.V.|date=2005 |title=The potential spread of infection caused by aerosol contamination of surfaces after flushing a domestic toilet |journal=Journal of Applied Microbiology |volume=99 |issue=2|pages=339–47|doi=10.1111/j.1365-2672.2005.02610.x|issn=1364-5072|pmid=16033465|s2cid=25625899}}</ref>  There is indirect evidence that specific pathogens such as [[norovirus]]<ref>{{Cite journal|last1=Widdowson|first1=Marc-Alain |last2=Glass |first2=Roger |last3=Monroe |first3=Steve |last4=Beard|first4=R. Suzanne|last5=Bateman|first5=John W.|last6=Lurie|first6=Perrianne|last7=Johnson |first7=Caroline |date=20 April 2005 |title=Probable transmission of norovirus on an airplane |journal=JAMA |volume=293 |issue=15 |pages=1859–60|doi=10.1001/jama.293.15.1859|issn=1538-3598|pmid=15840859}}</ref><ref>{{Cite journal|last1=Ho|first1=Mei-Shang|last2=Monroe|first2=Stephan S.|last3=Stine|first3=Sarah|last4=Cubitt|first4=David|last5=Glass|first5=Roger I.|last6=Madore|first6=H. Paul|last7=Pinsky|first7=Paul F.|last8=Ashley|first8=Charles|last9=Caul|first9=E.O.|date=21 October 1989|title=Viral Gastroenteritis Aboard a Cruise Ship|journal=The Lancet |language=en |volume=334 |issue=8669 |pages=961–65 |doi=10.1016/s0140-6736(89)90964-1 |pmid=2571872|s2cid=29429652|issn=0140-6736}}</ref> or [[SARS coronavirus]]<ref>{{Cite web|url=http://unpan1.un.org/intradoc/groups/public/documents/APCITY/UNPAN009480.pdf|title=Outbreak of Severe Acute Respiratory Syndrome (SARS) at Amoy Gardens, Kowloon Bay, Hong Kong: Main Findings of the Investigation|date=29 March 2011|website=Hong Kong Special Administrative Region Department of Health|archive-url=https://web.archive.org/web/20170420144829/http://unpan1.un.org/intradoc/groups/public/documents/APCITY/UNPAN009480.pdf|archive-date=20 April 2017|url-status=live}}</ref> could potentially be spread through toilet aerosols, but as of 2015 no direct experimental studies had clearly demonstrated or refuted actual disease transmission from toilet aerosols.<ref name="Mead20132">{{cite journal|last1=Johnson|first1=David L.|last2=Mead|first2=Kenneth R.|last3=Lynch|first3=Robert A.|last4=Hirst|first4=Deborah V.L.|date=March 2013|title=Lifting the lid on toilet plume aerosol: A literature review with suggestions for future research|journal=American Journal of Infection Control|volume=41|issue=3|pages=254–58|doi=10.1016/j.ajic.2012.04.330|pmc=4692156|pmid=23040490}}</ref><ref name="Jon2015">{{cite journal|last1=Jones|first1=R. M.|last2=Brosseau|first2=L. M.|date=May 2015|title=Aerosol transmission of infectious disease|journal=Journal of Occupational and Environmental Medicine|volume=57|issue=5|pages=501–08|doi=10.1097/JOM.0000000000000448|pmid=25816216|s2cid=11166016}}</ref>  It has been hypothesized that dispersal of pathogens may be reduced by closing the [[Toilet seat|toilet lid]] before flushing, and by using toilets with lower flush energy.<ref name="Mead20132" /><ref>{{Cite journal |last1=Best |first1=E.L. |last2=Sandoe |first2=J.a.T. |last3=Wilcox |first3=M.H. |date=1 January 2012 |title=Potential for aerosolization of Clostridium difficile after flushing toilets: the role of toilet lids in reducing environmental contamination risk |journal=The Journal of Hospital Infection |volume=80 |issue=1 |pages=1–5 |doi=10.1016/j.jhin.2011.08.010 |issn=1532-2939|pmid=22137761}}</ref>

==History==
{{See also|History of water supply and sanitation}}

===Pre-modern flush toilet systems===
[[File:Ostia-Toilets.JPG|thumb|right|[[Roman Empire|Roman]] public latrine found in the excavations of [[Ostia Antica]]]]
Forms of water flushed [[latrines]] have been found to exist since the [[Neolithic]]. The oldest neolithic village in Britain, dating from circa 31st century BC, [[Skara Brae]], [[Orkney]], used a form of hydraulic technology for [[sanitation]].<ref>{{Citation| title=Clean: a history of personal hygiene and purity | first=Virginia |last=Sarah Smith | url={{GBurl|id=GZBsRv17U3gC|q=Skara+Brae+drop+toilet}} | access-date=30 July 2010 | page=28| isbn=978-0-19-929779-5| year=2007| publisher=OUP Oxford |via=Google Books}}</ref><ref name="Pre">{{cite journal |last1=Childe |first1=V. |last2=Paterson |first2=J. |last3=Thomas |first3=Bryce |title=Provisional Report on the Excavations at Skara Brae, and on Finds from the 1927 and 1928 Campaigns. With a Report on Bones |journal=Proceedings of the Society of Antiquaries of Scotland |date=30 November 1929 |volume=63 |pages=225–280 |doi=10.9750/PSAS.063.225.280 |url=http://journals.socantscot.org/index.php/psas/article/view/7758/7726 |access-date=6 May 2020}}</ref><ref>{{cite news |last1=Suddath |first1=Claire |title=A Brief History of Toilets |url=http://content.time.com/time/health/article/0,8599,1940525,00.html |access-date=6 May 2020 |agency=Time |publisher=Time |date=19 November 2009}}</ref><ref>{{cite web |last1=Mark |first1=Joshua J. |title=Skara Brae |url=https://www.worldhistory.org/Skara_Brae/ |website=[[World History Encyclopedia]] |access-date=6 May 2020}}</ref><ref>{{cite journal |last1=Grant|first1=Walter G. |last2=Childe |first2=V. G.|title=A Stone-Age Settlement at the Braes of Rinyo, Rousay, Orkney. (First Report.)|journal=Proceedings of the Society of Antiquaries of Scotland |date=1938 |volume=72 |url=http://soas.is.ed.ac.uk/index.php/psas/article/download/8098/8066 |access-date=6 May 2020}}</ref><ref>{{Cite book|last1=Childe|first1=Vere Gordon|url={{GBurl|id=XI4wAQAAIAAJ|q=drain}}|title=Skara Brae|last2=Clarke|first2=D. V.|publisher=H.M.S.O., previously: Kegan Paul, Trench, Trubner & Company, Limited|year=1931|location=UK|pages=12, 20, 28|isbn=0-11-491755-8|language=en|via=Google Books}}</ref> The village's design used a stream, and connecting drainage system to wash waste away.

The Mesopotamians introduced the world to clay sewer pipes around 4000 BCE, with the earliest examples found in the Temple of Bel at [[Nippur]] and at [[Eshnunna]],<ref>{{cite book|last1=Burke|first1=Joseph|title=Fluoridated Water Controversy|url={{GBurl|id=fdIoDwAAQBAJ|p=2}}|access-date=4 August 2017|isbn=978-1-365-91287-0|date=24 April 2017|publisher=Lulu Press, Incorporated |via=Google Books}}</ref> utilised to remove wastewater from sites, and capture rainwater, in wells. The city of [[Uruk]] hosts the earliest known examples of brick constructed [[Latrine]]s, both squat and pedestal, from 3200 BCE.<ref>{{Cite book|last=Mitchell|first=Piers D.|url={{GBurl|id=HU6rCwAAQBAJ|p=263}}|title=Sanitation, Latrines and Intestinal Parasites in Past Populations|date=3 March 2016|publisher=Routledge|isbn=978-1-317-05953-0|pages=22|language=en|via=Google Books}}</ref><ref>{{Cite journal|last=Wald|first=Chelsea|date=26 May 2016|title=The secret history of ancient toilets|url=http://www.nature.com/news/the-secret-history-of-ancient-toilets-1.19960|journal=Nature News|language=en|volume=533|issue=7604|pages=456–458|doi=10.1038/533456a|pmid=27225101|bibcode=2016Natur.533..456W|s2cid=4398699}}</ref> Clay pipes were later used in the [[Hittites|Hittite]] city of [[Hattusa]].<ref>{{Cite book|last=Burney|first=Charles|url={{GBurl|id=azPl5Jzv930C|p=307}}|title=Historical Dictionary of the Hittites|date=19 April 2004|publisher=Scarecrow Press|isbn=0-8108-6564-5|language=en|via=Google Books}}</ref> They had easily detachable and replaceable segments, and allowed for cleaning.

Flushed toilet systems were constructed by people of the [[Indus Civilization]] at some places, and later Egyptians and the [[Minoan civilization]] did so next, while the latter developed by the second millennium BC flushable pedestal toilets, with examples excavated at [[Knossos]] and [[Akrotiri (Crete)|Akrotiri]].<ref name="Crete0">{{cite journal | last1=Yannopoulos | first1=Stavros | last2=Yapijakis | first2=Christos | last3=Kaiafa-Saropoulou | first3=Asimina | last4=Antoniou | first4=George | last5=Angelakis | first5=Andreas N. | title=History of sanitation and hygiene technologies in the Hellenic world | journal=Journal of Water, Sanitation and Hygiene for Development | publisher=IWA Publishing | volume=7 | issue=2 | date=2017-02-14 | issn=2043-9083 | doi=10.2166/washdev.2017.178 | pages=163–180| doi-access=free }}</ref>

Communal [[latrines]] were in use throughout the [[Roman Empire]], feeding into either primary or secondary sewers, from the first through fifth centuries AD. A very well-preserved example are the latrines at [[Housesteads]] on [[Hadrian's Wall]] in Britain. Such toilets did not flush in the modern sense, but had a continuous stream of running water to wash away waste. With the fall of the Western Roman Empire, these communal toilet systems fell into disuse in Western Europe, though continued in the Eastern Byzantine Roman Empire, with records of toilet pipes being renewed, and sewers repaired.<ref>{{Cite journal|last1=Yannopoulos|first1=Stavros|last2=Yapijakis|first2=Christos|last3=Kaiafa-Saropoulou|first3=Asimina|last4=Antoniou|first4=George|author5-link=Andreas N. Angelakis|last5=Angelakis|first5=Andreas N.|title=History of sanitation and hygiene technologies in the Hellenic World|url=https://www.academia.edu/35253971|journal=Journal of Water Sanitation and Hygiene for Development|year=2017|language=en|volume=7|issue=2|pages=163–180|doi=10.2166/washdev.2017.178|issn=2043-9083|doi-access=free}}</ref>

In February 2023 archeologists in China announced the discovery of the remains of what may be the world's oldest known flush toilet. Broken parts of the 2,400-year-old lavatory, as well as a bent flush pipe, were unearthed among ancient palace ruins in the Yueyang archaeological site in the central city of Xi'an by researchers from the Chinese Academy of Social Sciences' Institute of Archeology.<ref>{{cite web |title=2,400-year-old flush toilet discovered in China could be one of the oldest ever. |url=http://edition.cnn.com/style/article/china-oldest-toilet-remains-discovered-intl-hnk |website=CNN |language=en |date=22 February 2023}}</ref>

=== Development of the modern flush toilet ===
[[File:Cummings S-bend.jpg|thumb|right|[[Alexander Cumming]]'s 1775 patent for the [[Trap (plumbing)|S-trap]], which laid the foundations for the modern flush toilet.]]
In 1596 [[John Harington (writer)|Sir John Harington]] (1561–1612) published ''A New Discourse of a Stale Subject, Called the Metamorphosis of Ajax'', describing a forerunner to the modern flush toilet installed at his house at [[Kelston]] in [[Somerset]].<ref>{{Citation| last=Kinghorn |first=Jonathan | title=A Privvie in Perfection: Sir John Harrington's Water Closet | journal=Bath History | volume=1 | year=1986 | pages=173–88 | postscript=.|isbn=0-86299-294-X}}. Kinghorn supervised a modern reconstruction in 1981, based on the illustrated description by Harington's assistant Thomas Coombe in the ''New Discourse''.</ref> The design had a flush valve to let water out of the tank, and a wash-down design to empty the bowl. He installed one for his godmother [[Elizabeth I of England|Queen Elizabeth I]] at [[Richmond Palace]].

With the onset of the [[Industrial Revolution]] and related advances in technology, the flush toilet began to emerge into its modern form. A crucial advance in plumbing was the [[Trap (plumbing)|S-trap]], invented by the Scottish mechanic [[Alexander Cumming]] in 1775, and still in use today.<ref name="Cumming">{{cite news|title=From Charles Mackintosh's waterproof to Dolly the sheep: 43 innovations Scotland has given the world|url=https://www.independent.co.uk/news/uk/home-news/charles-mackintosh-chemist-waterproof-google-doodle-scotland-inventions-innovation-bicycles-a7499911.html|work=The independent|date=30 December 2016}}</ref> This device uses the standing water to seal the outlet of the bowl, preventing the escape of foul air from the sewer.<ref name="Cumming" /> His design had a sliding valve in the bowl outlet above the trap. Two years later, Samuel Prosser applied for a British patent for a "plunger closet".

[[File:Bramah water closet.jpg|thumb|left|[[Joseph Bramah]]'s improved version was the first practical flush toilet.]]
Prolific inventor [[Joseph Bramah]] began his professional career installing water closets (toilets) that were based on Alexander Cumming's patented design of 1775. He found that the current model being installed in London houses had a tendency to freeze in cold weather. In collaboration with a Mr. Allen, he improved the design by replacing the usual slide valve with a hinged flap that sealed the bottom of the bowl.

He also developed a float valve system for the flush tank. Obtaining the patent for it in 1778, he began making toilets at a workshop in Denmark Street, [[St Giles, London|St Giles]].<ref>{{Cite book|first=Alec|last=Skempton|title=A Biographical Dictionary of Civil Engineers in Great Britain and Ireland: Vol 1: 1500 to 1830|publisher=Thomas Telford|year=2002|isbn=0-7277-2939-X|display-authors=etal}}</ref> The design was arguably the first practical non-manual flush toilet, and production continued well into the 19th century, used mainly on boats. [[Thomas Edward Bowdich|Thomas Bowdich]], an English traveller, visited [[Kumasi]], capital of the [[Ashanti Empire]] in 1817 and mentioned that majority of the houses in the city especially those near the king's palace included indoor toilets that were flushed with gallons of boiling water.<ref>{{cite book |url={{GBurl|id=Tkm5UZJz8z0C|q=Indoor+toilets}}|last=Edgerton |first=Robert B. |year=2010 |title=The Fall of the Asante Empire: The Hundred-Year War For Africa's Gold Coast |page=26|publisher=Simon and Schuster |isbn=978-1-4516-0373-6|via=Google Books}}</ref>

=== Industrial production ===
[[File:Ad 1884 twyford.jpg|thumb|right|[[Thomas William Twyford]] was one of the leading marketers of flush toilets in their first boom of popularity after the [[Great Exhibition]] of 1851.]]

It was only in the mid-19th century, with growing levels of urbanisation and industrial prosperity, that the flush toilet became a widely used and marketed invention. This period coincided with the dramatic [[Sewage collection and disposal|growth in the sewage system]], especially in [[London]], which made the flush toilet particularly attractive for health and sanitation reasons.

[[George Jennings]] established a business manufacturing water closets, salt-glaze drainage, sanitary pipes and sanitaryware at Parkstone Pottery in the 1840s, where he popularized the flush toilet to the middle class. At [[The Great Exhibition]] at [[Hyde Park, London|Hyde Park]] held from 1 May to 15 October 1851, George Jennings installed his Monkey Closets in the Retiring Rooms of [[The Crystal Palace]]. These were the first public [[pay toilet]]s (free ones did not appear until later), and they caused great excitement. During the exhibition, 827,280 visitors paid one penny to use them; for the penny they got a clean seat, a towel, a comb, and a [[shoe shine]]. "To spend a penny" became a [[euphemism]], for going to the toilet.<ref>{{cite web |date=7 June 2016 |title=Toilet remains from 'spend a penny' exhibition uncovered in Hyde Park |publisher=The Royal Parks |access-date=16 November 2016 |url=https://www.royalparks.org.uk/press-and-media/press-releases/toilet-remains-from-spend-a-penny-exhibition-uncovered-in-hyde-park |archive-date=2 February 2017 |archive-url=https://web.archive.org/web/20170202003742/https://www.royalparks.org.uk/press-and-media/press-releases/toilet-remains-from-spend-a-penny-exhibition-uncovered-in-hyde-park |url-status=dead }}</ref><ref name="NYTimes Krinsky">{{citation  |url=https://query.nytimes.com/gst/fullpage.html?res=9E0CE4D7103CF931A35750C0A96F958260 |title=Of Facts and Artifacts |last=Krinsky |first=William L. |date=2 March 1999 |newspaper=New York Times |access-date=2 March 2009}}</ref><ref name="NYTimes Wilson">{{citation |url=http://papercuts.blogs.nytimes.com/2008/12/16/tom-the-plumber/ |title=Tom the Plumber |last=Wilson |first=Blake |date=16 December 2008 |newspaper=New York Times |access-date=2 March 2009}}</ref>

[[File:Windermere Hotel Urinal Plaque.JPG|thumb|left|[[George Jennings]] trademark on his manufactures]]
When the exhibition finished and moved to [[Sydenham, London|Sydenham]], the toilets were to be closed down. However, Jennings persuaded the organisers to keep them open, and the toilet went on to earn over £1,000 a year. He opened the first underground convenience at [[Royal Exchange (London)|the Royal Exchange]] in 1854. He received a patent in 1852 for an improved construction of water-closet, in which the pan and trap were constructed in the same piece, and so formed that there was always a small quantity of water retained in the pan itself, in addition to that in the trap which forms the water-joint. He also improved the construction of valves, drain traps, forcing pumps and pump-barrels. By the end of the 1850s building codes suggested that most new middle-class homes in British cities were equipped with a water closet.<ref>{{cite web | url=https://environment7.uwe.ac.uk/resources/constructionsample/Conweb/house_ages/elements/print.htm | archive-url=https://web.archive.org/web/20140307165422/https://environment7.uwe.ac.uk/resources/constructionsample/Conweb/house_ages/elements/print.htm | archive-date=2014-03-07 | title=Evolution of Building Elements }}</ref>

Another pioneering manufacturer was [[Thomas William Twyford]], who invented the single piece, ceramic flush toilet.<ref name="Eveleigh - Twyford">David J. Eveleigh, 'Twyford, Thomas William (1849–1921)', Oxford Dictionary of National Biography, Oxford University Press, May 2009; online edn, May 2011</ref> The 1870s proved to be a defining period for the sanitary industry and the water closet; the debate between the simple water closet trap basin made entirely of earthenware and the very elaborate, complicated and expensive mechanical water closet would fall under public scrutiny and expert opinion.<ref name="Eveleigh - Twyford" /> In 1875 the "wash-out" trap water closet was first sold, and was found as the public's preference for basin type water closets. By 1879 Twyford had devised his own type of the "wash out" trap water closet; he titled it the "National", and it became the most popular wash-out water closet.<ref name="Eveleigh - Twyford" />

[[File:Thomas Crapper toilet ad.gif|thumb|right|Flush toilets were widely available from the mid to late 19th century. Although [[Thomas Crapper]] did not invent the flush toilet, he was a leading manufacturer.]]

By the 1880s the free-standing water closet was on sale and quickly gained popularity; the free-standing water closet was able to be cleaned more easily and was therefore a more hygienic water closet. Twyford's "Unitas" model was free-standing and made completely of earthenware. Throughout the 1880s he submitted further patents for improvements to the flushing rim and the outlet. Finally, in 1888 he applied for a patent protection for his "after flush" chamber; the device allowed the basin to be refilled by a lower quantity of clean water in reserve after the water closet was flushed.<ref>{{Cite book|url={{GBurl|id=1_iGvgAACAAJ}}|title=Oxford Dictionary of National Biography: In Association with the British Academy|last1=Matthew|first1=H. C. G.|last2=Harrison|first2=Brian|date=2004|publisher=OUP Oxford|isbn=0-19-861411-X|language=en|via=Google Books}}</ref> The modern pedestal "flush-down" toilet was demonstrated by Frederick Humpherson of the Beaufort Works, [[Chelsea, London|Chelsea]], England in 1885.<ref name="Eveleigh">{{Citation|first=David J.|last=Eveleigh|title=Privies and Water Closets|location=Oxford|publisher=Shire Publications|year=2008|isbn=978-0-7478-0702-5}}</ref>

The leading companies of the period issued catalogues, established showrooms in department stores and marketed their products around the world. Twyford had showrooms for water closets in [[Berlin]], Germany; [[Sydney]], Australia; and [[Cape Town]], South Africa. The [[Public Health Act 1875]] set down stringent guidelines relating to sewers, drains, water supply and toilets and lent tacit government endorsement to the prominent water closet manufacturers of the day.

Contrary to popular legend, Sir [[Thomas Crapper]] did not invent the flush toilet. He was, however, in the forefront of the industry in the late 19th century, and held nine patents, three of them for water closet improvements such as the floating [[ballcock]]. In 1880, Thomas Crapper introduced the [[Trap (plumbing)|U-shaped trap]].{{cn|date=October 2023}} His flush toilets were designed by inventor Albert Giblin, who received a British patent for the "Silent Valveless Water Waste Preventer", a siphon discharge system.<ref name="Giblin" /> Crapper popularized the siphon system for emptying the tank, replacing the earlier floating valve system which was prone to leaks.<ref>{{citation |last=Hart-Davis |first=Adam |title=Thomas Crapper&nbsp;– Fact and Fiction |url=http://www.exnet.com/1995/11/01/science/science.html |publisher=ExNet |access-date=13 May 2010}}</ref><ref name="Giblin">{{cite patent |inventor-last=Giblin |inventor-first=Albert |title=Improvements in Flushing Cisterns |country=GB |number=189804990 |pubdate=1898-04-09 |fdate=1898-03-01 }}</ref><ref>{{cite patent |inventor1-last=Crapper |inventor1-first=George |inventor2-last=Wharam |inventor2-first=Robert Marr |title=Improvements in or relating to Automatic Syphon Flushing Tanks |number=189700724 |country=GB |fdate=1897-01-11 |pubdate=1897-03-06 }}</ref>

{{anchor|Edward Johns}}
Rev. Edward Johns, introduced his ''Dolphin toilet'' to the United States at the 1876 [[Centennial Exposition]] in [[Philadelphia]], attributed to Edward Johns & Co of [[Armitage]], [[Staffordshire]],<ref name="leeds.gov.uk/IMG_20210721_134652.jpg">{{cite web |title=The Dolphin toilet. Normally attributed to Edward Johns & Co of Armitage, Staffordshire, 1885-1889. |url=https://news.leeds.gov.uk/resources/xmgzw-h2ol2-p6msj-cdcpy-2ejzp |website=Leeds City Museum |publisher=Leeds City Council |access-date=21 October 2023 |language=en}}</ref><ref name="nytimes/1992/01/23/english-bathrooms">{{cite news |last1=Schmidt |first1=William E. |title=English Bathrooms: Out of the Closet |url=https://www.nytimes.com/1992/01/23/garden/english-bathrooms-out-of-the-closet.html |access-date=21 October 2023 |work=[[The New York Times]] |date=1992-01-23}}</ref><ref>{{cite book |title=The Pottery & Glass Trades' Journal; Volume 1, Issue 2 |date=1878 |publisher=J. Everett |page=345 |url={{GBurl|id=hyUGAAAAQAAJ|pg=RA1-PA345}} |via=Google Books}}</ref><ref name="jldr/crapperloo">{{cite web |title=Antique Loo's from the Thomas Crapper Company Collection |url=https://www.jldr.com/crapperloo.html |website=jldr.com |access-date=21 October 2023}}</ref><ref name="google/patent/GB528110">{{cite web |author1=Edward Johns & Co Ltd |title=GB528110A - Improvements in water closet basins |url=https://patents.google.com/patent/GB528110A/en |website=Google Patents |access-date=21 October 2023 |language=en |date=1939-03-14 |quote=23 October 1940}}</ref><ref name="baus.org.uk/museum/164">{{cite web |title=A Brief History of The Flush Toilet |url=https://www.baus.org.uk/museum/164/a_brief_history_of_the_flush_toilet |website=[[British Association of Urological Surgeons]] |access-date=21 October 2023}}</ref>

<blockquote>"The American slang term for the toilet, “the john,” is said to be derived from the flushing water closets at Harvard University installed in 1735, and emblazoned with the manufacturer’s name, Rev. Edward Johns."<ref name="surfacesreporter/10241">{{cite news |title=HISTORY OF MODERN FLUSH TOILETS! |url=https://surfacesreporter.com/articles/10241/history-of-modern-flush-toilets |access-date=21 October 2023 |work=surfacesreporter.com |date=5 April 2017}}</ref></blockquote>

=== Spread and further developments ===
Although flush toilets first appeared in Britain, they soon spread to the [[Continental Europe|Continent]]. The first such examples may have been the three "waterclosets" installed in the new town house of banker ''Nicolay August Andresen'' on 6 Kirkegaten in [[Oslo|Christiania]], insured in January 1859. The toilets were probably imported from Britain, as they were referred to by the English term "waterclosets" in the insurance ledger. Another early watercloset on the European continent, dating from 1860, was imported from Britain to be installed in the rooms of [[Queen Victoria]] in [[Ehrenburg Palace]] ([[Coburg]], Germany); she was the only one who was allowed to use it. Flush toilets were sold in [[Batavia, Dutch East Indies|Batavia]], Dutch East Indies in [[1872]].<ref name="Bataviaasch Handelsblad">{{cite news |title=Bataviaasch Handelsblad, 15 November 1872 |url=https://resolver.kb.nl/resolve?urn=ddd:110534344:mpeg21:a0008 |newspaper=Bataviaasch Handelsblad | date=15 November 1872 |access-date=28 December 2022}}</ref>

In America, the chain-pull indoor toilet was introduced in the homes of the wealthy and in hotels, soon after its invention in England in the 1880s. Flush toilets were introduced in the 1890s. [[William Elvis Sloan]] invented the [[Flushometer]] in 1906, which used pressurized water directly from the supply line for faster recycle time between flushes. The Flushometer is still in use today in public restrooms worldwide. The vortex-flushing toilet bowl, which creates a self-cleansing effect, was invented by Thomas MacAvity Stewart of [[Saint John, New Brunswick]], in 1907.<ref>Mario Theriault, ''Great Maritime Inventions 1833–1950'', Goose Lane Editions, 2001, p. 34.</ref> [[Philip Haas (inventor)|Philip Haas]] of [[Dayton]], [[Ohio]], made some significant developments, including the flush rim toilet with multiple jets of water from a ring and the water closet flushing and recycling mechanism similar to those in use today.

The company [[Caroma]] in Australia developed the Duoset cistern with [[Dual flush toilet|two buttons and two flush volumes]] as a water-saving measure in 1980. Modern versions of the Duoset are now available worldwide, and save the average household 67% of their normal water usage.<ref name=":1">{{Cite book|url={{GBurl|id=FQEJAAAAQBAJ}}|title=A People and a Nation: A History of the United States, Volume II: Since 1865|last1=Norton|first1=Mary Beth|last2=Sheriff|first2=Carol|last3=Blight|first3=David W.|last4=Chudacoff|first4=Howard|date=2011|publisher=Cengage Learning|isbn=978-1-133-17188-1|page=504|language=en|via=Google Books}}</ref>

==Manufacture==
A toilet's body is typically made from vitreous china, which starts out as an aqueous suspension of various minerals called a [[Slip (ceramics)|slip]]. It takes about {{convert|20|kg|lb|abbr=in}} of slip to make a toilet.{{citation needed|date=July 2016}}

In traditional casting, the slip is poured into the space between [[plaster of Paris]] molds. The toilet bowl, rim, tank and tank lid require separate molds. The molds are assembled and set up for filling and the slip-filled molds sit for about an hour after filling. This allows the plaster molds to absorb moisture from the slip, which makes it semi-solid next to the mold surfaces but lets it remain liquid further from the surface of the molds. Then, the workers remove plugs to allow any excess liquid slip to drain from the cavities of the mold (this excess slip is recycled for later use). The drained-out slip leaves hollow voids inside the fixture, using less material to keep it both lighter and easier to fire in a [[kiln]]. This molding process allows the formation of intricate internal waste lines in the fixture; the drain's hollow cavities are poured out as slip.

At this point, the toilet parts without their molds look like and are about as strong as soft clay. After about one hour the top core mold (interior of toilet) is removed. The rim mold bottom (which includes a place to mount the holding tank) is removed, and it then has appropriate slanted holes for the rinsing jets cut, and the mounting holes for tank and seat are punched into the rim piece. Valve holes for rapid water entry into the toilet are cut into the rim pieces. The exposed top of the bowl piece is then covered with a thick slip and the still-uncured rim is attached on top of the bowl so that the bowl and hollow rim are now a single piece. The bowl plus rim is then inverted, and the toilet bowl is set upside down on the top rim mold to hold the pieces together as they dry. Later, all the rest of the mold pieces are removed. As the clay body dries further it hardens more and continues to shrink. After a few hours, the casting is self-supporting, and is called [[pottery|greenware]].

After the molds are removed, workers use hand tools and sponges to smooth the edges and surface of the greenware, and to remove the mold joints or roughness: this process is called "fettling". For large scale production pieces, these steps may be automated. The parts are then left outside or put in a warm room to dry, before going through a dryer at about {{convert|93|C|F}}, for about 20–36 hours.

[[File:Worker polishing a toilet commode.jpg|thumb|Spraying glaze onto a closet]]
After the surfaces are smoothed, the bowls and tanks are sprayed with [[ceramic glaze|glaze]] of various kinds to get different colors. This glaze is designed to shrink and contract at the same rate as the greenware while undergoing firing. After being sprayed with glaze, the toilet bowls, tanks, and lids are placed in stacks on a conveyor belt or "car" that slowly goes through a large kiln to be [[Pottery|fired]]. The belt slowly moves the glaze-covered greenware into a tunnel kiln, which has different temperature zones inside it starting at about {{convert|200|C|F}} at the front, increasing towards the middle to over {{convert|1200|C|F}} degrees, and exiting at about {{convert|90|C|F}}. During the firing in the kiln, the greenware and glaze are vitrified as one solid finished unit. Transiting the kiln takes glaze-covered greenware around 23–40 hours.

After the pieces are removed from the kiln and fully cooled, they are inspected for cracks or other defects. Then, the flushing mechanism may be installed on a one-piece toilet. On a two-piece toilet with a separate tank, the flushing mechanism may only be placed into the tank, with final assembly at installation.

A two-piece attaching [[toilet seat|seat and toilet bowl lid]] are typically mounted over the bowl to allow covering the toilet when it is not in use and to provide seating comfort. The seat may be installed at the factory, or the parts may be sold separately and assembled by a plumbing distributor or the installer.

==Water usage==

[[File:BelizeCity75CityFlushToilet.jpg|thumb|upright|right|The bowl drain is visible at the rear of the bowl, connected to the waste pipe.]]
The amount of water used by conventional flush toilets is usually a significant portion of personal daily water usage: for example, five {{convert|10|L|USgal|abbr=in}} flushes per day use {{convert|50|L|USgal|abbr=in}}.

Modern low-flush toilet designs allow the use of much less water per flush, {{convert|4.5|to|6|L|USgal|abbr=in}} per flush.{{citation needed|date=October 2016}}

Dual flush toilets allow the user to select between a flush for urine or feces, saving a significant amount of water over conventional units. Dual flush may be accomplished by pushing the flush handle up or down,<ref>{{cite web|url=http://cronkitenews.jmc.asu.edu/?p=315|title=Tucson lawmaker wants tax credits for water-conserving toilet |date=18 January 2008 |publisher=Cronkite News Service|access-date=12 March 2008}}</ref> or a two-segment flush pushbutton may be used whereby pressing the smaller section releases less water.

===Flushing with non-potable water sources===
Raw water flushing, including seawater flushing, is a method of [[water conservation]], where [[raw water]], such as [[seawater]], is used for flush toilets. Such systems are used in places such as the majority of cities and towns in Hong Kong (see [[water supply and sanitation in Hong Kong]]),<ref name="test">[http://www.scmp.com/news/hong-kong/article/1463333/seawater-flushing-be-extended-more-hong-kong-toilets-next-year Seawater flushing to be extended to more Hong Kong toilets next year], [[South China Morning Post]], 3 April 2014.</ref> [[Gibraltar]], and [[Avalon, California]], United States.{{citation needed|date=April 2015}}  [[Head (watercraft)|Heads (on ships)]] are typically flushed with [[seawater]].

Flush toilets may, if plumbed for it, use [[greywater]] (water previously used for washing dishes, laundry and bathing) for flushing rather than drinkable [[potable water]].

== Etymology ==
{{Further|Toilet#Names|Toilet (room)#Names}}

===Water closet===
{{Redirect|Water closet|the room in a house with only a toilet|Toilet (room)|rooms labelled "W.C."|Public toilet}}
The word "toilet" initially meant "wash-room", without reference to sanitary facilities. Early indoor toilets were known as [[garderobe]]s because they were used to store clothes, as the smell of [[ammonia]] was found to deter fleas and moths. However, an [[outhouse]] was usual until the nineteenth century, and only a few wealthy houses and luxury hotels had indoor toilets connected to drains and sewers. Lidded "chamber pots", kept in specially designed bedside cabinets and used in bedrooms by ladies and invalids, and portable bathtubs, could be emptied and washed in an [[outhouse]].

From the sixteenth century in [[England]], a private room (a closet) with a flushing toilet was referred to as a Water Closet ("WC"), in contrast with an Earth Closet ("EC"), an abbreviation still used in 1960s Oxfordshire cottage sales.{{citation needed|date=August 2021}}

The descriptive terms "wash-down closet" or "water closet"<ref>Leamington Spa Courier, 2 April 1853</ref> only reached the United States in the 1880s. By 1890 there was increased public awareness of disease and of carelessly disposed human waste being infectious.<ref name=":1"/>

In common North American usage, a residential "[[bathroom]]" usually contains a toilet, a lavatory, and a bath. However, a commercial bathroom (or “restroom”) contains toilets or urinals but no bath, to the confusion of foreigners. In the UK, Australia and NZ, "bathroom" or bath-room refers to a room with a fixed bathtub and not necessarily a toilet. The terms "bathroom", and "toilet" or "loo" (amongst other euphemisms) indicate distinct functions, although bathrooms may often include toilets.

The term "water closet", refers to a room that has both a toilet and other plumbing fixtures such as a sink or a bathtub. American plumbers and codes use the term "water closet" or "WC" to denote a small room or enclosure with a toilet which is usually located within a larger bathroom that contains other fixtures such as a sink and tub. 

Many European languages refer to a toilet as a "water" or "WC". The [[Diccionario de la lengua española de la Real Academia Española|Royal Spanish Academy Dictionary]] accepts "''váter''" as a name for a toilet or bathroom, which is derived from the British term "water closet". France uses the expressions ''aller aux waters'' ("to go to the waters") derived from "water closet", and "w.-c." {{IPA|fr|ve.se|pron}}. Likewise the Romanian word "''veceu''" {{IPA|ro|veˈtʃeu|pron}}, and the Finnish word "''vessa''" {{IPA|fi|ˈʋesːɑ|pron}} derive from a shortened version of the abbreviation. In German, the expression "''Klo''" {{IPA|de|kloː|pron}} (first syllable of "''Klosett''") is used alongside "WC". In Italian WC {{IPA|it|vutˈtʃi|pron}} or {{IPA|it|vitˈtʃi|}}, and "''water''" {{IPA|it|ˈvaːter|pron}}, are very common terms to refer to the flushing toilet. In Dutch WC {{IPA|nl|ˌʋeː ˈseː|pron}} is the most common term.

== Society and culture ==

=== Swirl direction myth ===
It is a [[common misconception]] that when flushed, the water in a toilet bowl swirls one way if the toilet is north of the equator and the other way if south of the equator, due to the [[Coriolis effect]] – usually, counter clockwise in the northern hemisphere, and clockwise in the southern hemisphere. In reality, the direction that the water takes is much more determined by the direction that the bowl's rim jets are pointed, and it can be made to flush in either direction in either hemisphere by simply redirecting the rim jets during manufacture. The relative importance of the Coriolis force can be determined by a ratio known as the [[Rossby number]]. When this number is much larger than 1, the Coriolis force is insignificant compared to the inertia effects. On the scale of bathtubs and toilets, the Rossby number is on the order of billions,<ref>{{cite web|url=https://oikofuge.com/coriolis/|accessdate=2022-12-15|title=Phenomena Coriolis|date=25 January 2017 |publisher= The Oikofuge, 2015-2022}}</ref> and so the Coriolis effect is too weak to be observed except under carefully controlled laboratory conditions.<ref>[http://www.straightdope.com/columns/read/149/do-bathtubs-drain-counterclockwise-in-the-northern-hemisphere "Do bathtubs drain counterclockwise in the Northern Hemisphere?"], ''The Straight Dope'', 15 April 1983</ref>

=== Courtesy flush ===
Since the 1990s, the slang term "courtesy flush" refers to a mid-defecation flush of the toilet as a courtesy to other bathroom users or other prisoners in a cell.<ref>{{Cite book|last=Anmol|first=Salim Khan|url={{GBurl|id=UFIMEAAAQBAJ|p=166}}|title=Slangs Dictionary of Unconventional English|date=2020-12-03|publisher=Sakha Global Books (Sakha Books)|pages=166|language=en|via=Google Books}}</ref> A courtesy flush can serve to reduce odor and cover noise.<ref>{{Cite book|last=Praeger|first=Dave|url={{GBurl|id=M09jCwAAQBAJ|p=78}}|title=Poop Culture: How America Is Shaped by Its Grossest National Product|date=2009-05-01|publisher=Feral House|isbn=978-1-932595-62-8|pages=78|language=en|via=Google Books}}</ref>

==See also==
* [[Toilets in Japan]]
* [[Thomas Maddock]], started the American indoor toilet industry

==References==
{{Reflist}}

==External links==
{{Commons category-inline|Flush toilets}}
*{{YouTube|id=75tPRujxarM|title=How Its Made...}} {{Dead link|date=January 2024}} {{Retrieved|access-date=26 September 2011}}

{{Plumbing}}
{{Toilets|state=expanded}}
{{Authority control}}

{{DEFAULTSORT:Flush Toilet}}
[[Category:Bathrooms]]
[[Category:British inventions]]
[[Category:16th-century inventions]]