|WikiProject Chemistry||(Rated Start-class, Mid-importance)|
Formula Missing 
Hi, There is a formula missing that was in the old section:
CaCO3(s) + H2O(l) + CO2(g) ⇌ Ca2+(aq) + 2HCO3-(aq)
Please put it back!
What is the level of hard water in Charlottsville, Virginia Beach, Richmond, Well water, and Washington D.C.?
Hard water usually consists of calcium, magnesium ions, and possibly other dissolved compounds such as bicarbonates and sulfates.
Hard Water 
Permanent Hardness 
An anonymous contributor asserted this:
"It has to be in more then 50gms/dm3 in concentration to be called permanent hard water."
Any back-up/citation for this?
WLD 10:20, 25 March 2006 (UTC)
Hot Lime Softening 
In industrial processes, boiler operation in particular, water is often softened with a Hot-Lime softener, I have done superficial wiki searches and haven't come up with anything referring to hot-lime softening. If anyone can clarify this for me, that'd be great. Otherwise, I will create an article about Hot-Lime softeners. 126.96.36.199 02:25, 17 April 2006 (UTC)
The deposites of Calcium, Limescale, ect. left after hard water has been on a surface and evaporated is often refered to as hard water; however, this is ironic as there is no longer any water present.
Isn't this called a hard water stain? PrometheusX303 20:10, 16 May 2006 (UTC)
Apparent Error in Article 
The conversion from mg/L of calicum to other hardness scales seems to be bogus. For example, the conversion in the article to German degrees says that 3mg/L of calcium equals 21°dH. According to information I have from a water-testing kit, 21°dH is very hard water. However, other sources on the web say that 3mg/L is very soft water. Perhaps instead of "divide by", the author meant "multiply by".
- Read the article carefully - it does not say what you think it does. 21°dH converts to 150 mg/L, which is 'Very Hard'. 21 divided by 0.14 is 150. WLD 21:10, 15 October 2006 (UTC)
- It is difficult here, not to mix mg/l of calcium-ions and mg/l of CaCO3.
- 21°dH converts to 3,8 mol/l CaCO3, which means 380 mg/l CaCO3 or 210 mg/l CaO or 150 mg/l Ca++. This is why I prefer mol/l.
- In the section "Hard water in australia" it should - in my opinion - say "as Ca" because 100 mg/l CaCO3 are 1 mol/l or 5,6 °dH which is not hard at all.
- As being german, I find it confusing to find data in water analysis sheets like: "5 ppm CL- as CaCO3". I can't make sense of that.I. G. Bauer 16:32, 4 September 2007 (UTC)
Doubtful etymology 
"Earlier generations coined the phrase 'hard water' because it made cleaning difficult. Hardness is caused by compounds of calcium and magnesium. All freshwater sources contain calcium and magnesium in varying quantities."
That sounds suspect - the opposite of hard water is soft water, not easy water, plus other languages use words for "hard" water which don't include the meaning "difficult". Zocky | picture popups 02:27, 7 November 2006 (UTC)
The correct etymology is from the hardness of beans soaked or cooked in various waters. I first came across this in a chemistry book I read over 40 years ago. The fact that it does vary the hardness of beans is easily verified. 188.8.131.52 16:53, 9 March 2007 (UTC)firstname.lastname@example.org
- If you can cite the book, fine, but it is an extraordinary claim. I would suggest that the book in question may well be incorrect, but as Wikipedia is based on verifiability, not truth, if you can cite it, it would belong in the article. Regards, WLDtalk|edits 17:09, 9 March 2007 (UTC)
- I checked the referred pdf, and the references given in it. The given pdf does not say the origin of the term 'hard water' is from the behaviour of cooked beans. Of the three references cited in the pdf, the two web references are no longer valid. A better citation would be required. Best. WLDtalk|edits 18:31, 9 March 2007 (UTC)
Funnily enough, my GCSE chemistry folder from Oxford Open Learning makes the same claim about water used to soften beans, and adds it originated during the American Civil War. So naturally I came here for verification. It is either the least known brilliant story, or just an urban myth. —Preceding unsigned comment added by 184.108.40.206 (talk) 02:53, 24 May 2009 (UTC)
This seems to be a marketing exercise for water softeners - "unsightly spots on dishes" indeed. Colonel Mustard 03:08, 28 November 2006 (UTC)
- Well, I have very hard water at my house and yes, you have to towel-dry your dishes or there are spots even from just a drop, all our plumbing fixtures are encrusted, and if you leave a pan of water out and it all dries up, good luck getting that scale off... I'm no fan of water softeners but it is a legitimate observation. (220.127.116.11 (talk) 17:37, 24 November 2010 (UTC))
Conversion to/from Clarks seems off 
I have also encountered a problem with the conversion table (under Types of Measurement). The formula x Clark degrees / 0.175 = y ppm seems off.
In the conversion table it says conversion to mg/L calcium: divide by 0.175. Put to practice: I have 1 Clark degree. To get mg/L I divide by 0.175, i.e. approx. 5.7 mg/L, which should be the same as 5.7 ppm. Yet in the next line One degree Clark corresponds to one grain of calcium carbonate in one Imperial gallon of water which is equivalent to 14.28 parts calcium carbonate in 1,000,000 parts water. – i.e. 14.28 parts per million.
The University of North Carolina's Dictionary of Units Measurement also states the Clark degree is defined as 1 part of calcium carbonate per 70 000 parts of water; this is about 14.3 parts per million (ppm). And Global Water Instrumentation, Inc. has a table stating that 1 ppm = 0.07 Clark degrees, which corresponds to 1 Clark degree = 14.3 ppm.
Could someone check this pls? I’m just a translator attempting to convert French water hardness levels into English ones. Merci beaucoups. 18.104.22.168 16:26, 17 December 2006 (UTC)
- You are correct. Formerly, the article tried to define these units and conversion factors in terms of calcium *ion* concentrations, rather than as concentrations of the actual calcium compounds (CaCO3, CaO) used in the original definitions. While not strictly speaking incorrect, these descriptions were confusing, imprecise, and unhelpful. This has now been fixed in the article.22.214.171.124 (talk) 00:22, 27 January 2009 (UTC)
Vandalism Corrected 
I have corrected vandalism within the first line of the article. Please view the revision history for details. Chrisbrl88 08:38, 25 February 2007 (UTC)
World-wide view 
How is hard-water viewed in non-English speaking parts of the world? Why do we need a warning tag that warns us that this is not a global world-view on Hard Water? Do people in China doubt that Australia has hard water issues? I don't get it, so I'm removing the tag. Vivaldi (talk) 05:33, 25 March 2007 (UTC)
Hard, heavy, WTF's the big difference anyway? 
In the early Flash comics of the 1940s, Jay Garrick's fantastic speed is attributed to inhaling "hard water fumes" that render him a "freak of science". See here for comical mumbo-jumbo. Asat 02:40, 17 September 2007 (UTC)
- Sounds like somebody had hard water confused with heavy water. Not that heavy water has "fumes" (it has vapor or steam, just like regular water) or is going to turn you into a "freak of science". But it is slightly radioactive, so a reference to it makes a little more sense. In a comic book, that is! Isaac R (talk) 20:21, 6 October 2008 (UTC)
Magnetic Water Conditioners 
I am aware that there are magnetic appliances that can remove the hardness in water. If some one knows more about this, I feel it would be beneficial for it to be included in this article. —Preceding unsigned comment added by Claughton (talk • contribs) 16:38, 7 February 2008 (UTC)
The usefulness of magnetic appliances is still in doubt. The situation is well described on the following webpage:. At this point, given that the scientific evidence for the utility of these approaches is still not proven it's probably best to leave them out. --Libravore (talk) 23:07, 15 April 2009 (UTC)
Calcium ion health benefits/concerns 
- I've heard that. Supposedly the hardness of the water in Kentucky (the whole state is on a huge calcium carbonate shelf) is one reason that state is famous for its horses — stronger bones. (It's also said to enhance the flavor of their Bourbon.) But this could be a myth: water hardness is measured in parts per million, meaning you'd have to drink a lot of hard water to get your MDA. More hard data is needed before we can add this tidbit. --Isaac R (talk) 18:21, 18 August 2008 (UTC)
- Calcium and magnesium can be a boon for people without enough in their diet (which for magnesium is a lot of people), but can also be over-consumed. It would seem that sufficiently hard water has enough minerals in it to require accounting for, in individuals who are sensitive to Milk-alkali_syndrome for example. It would be nice if someone with nutritionist creds could speak to the bio-availability of the minerals in hard water, though it would seem to the layman (like me) that hard water and a Rolaids dissolved in soft water would be roughly equivalent, but who knows maybe some other factors prevent absorbtion. If we can get some confirmation on bio-availability, maybe linking the hard water article in on the pages for dietary magnesium and the section on the antacid page about health effects and relevant sub-pages might be in order. (126.96.36.199 (talk) 17:30, 24 November 2010 (UTC))
Why do we care? 
These twe sentences can't both be right 
"Hardness in water is defined as the presence of multivalent cations." "... a single-number scale does not adequately describe hardness" -> it does it's expressed for example in °f. It probably means that a classification water from (very) soft to (very) hard is not universal. —Preceding unsigned comment added by 188.8.131.52 (talk) 10:33, 20 August 2008 (UTC)
- The first sentence describe a qualitative measure (i.e., it's either hard or not), the second a quantitative measure (if hard, then how hard is it). 184.108.40.206 (talk) 18:17, 28 October 2008 (UTC)
- It might also be referring to the fact that there are different ions involved, not just always Calcium. (220.127.116.11 (talk) 17:41, 24 November 2010 (UTC))
USGS information 
I was interested in the number of households with hard water, so I went to the USGS site to try to find where this statistic came from and could not find it anywhere! The USGS does analysis of ground water and surface water and wells (whichever category those go in), not the water coming out of people's taps in their homes, so how could this be a USGS statistic that "households" have hard or soft water? I was hoping that someone at USGS had at least done something like multiplied the population of different areas by the type of ground/surface water prevalent in that area, but that doesn't seem to be the case. Even then you'd have to make assumptions about the prevalence of water softeners in homes. If anyone can find the primary citation for this "fact" it would improve the accuracy of this article.--Libravore (talk) 23:17, 15 April 2009 (UTC)
Also on the topic of the USGS citation, their scale of classification for water hardness is quite different to the scale used by the Drinking Water Inspectorate in the UK: http://dwi.defra.gov.uk/consumers/advice-leaflets/hardness_map.pdf. Is there an internationally accepted scale, or should the UK (and potentially other) scales be cited for balance? Joshdwek (talk) 10:07, 19 December 2011 (UTC)
This is regarding a confusing comment in italics. There is an aside that states, “This scale is in substantial disagreement with the references.” The comment is intended as a warning. What is not clear is the confidence that the authors/editors have in the following table. Nor does the “Wikipedia:Manual of Style”, make the purpose clear other than to add emphisis. I assume the author is also in substantial disagreement with the references--"This scale is in substantial disagreement with the references, which are considered inaccurate." However, one could assume that the editors are uncertain why the table is in substantial disagreement with the references--"This scale is in substantial disagreement with the references, which may be more accurate." --Tychicusole (talk) 17:15, 27 July 2010 (UTC)
Avoiding hard water 
- I lived in Rugby, Warwickshire (England) until 1964, and the town tap water was very hard. Rain water (which is soft) that fell on the back part of our house's roof was collected in an open tank on the coalhouse roof and was led to a special tap in the kitchen; my mother heated it and used it for washing hair. Anthony Appleyard (talk) 09:45, 6 October 2010 (UTC)
- The connection with rainfall is important. Comparing maps of water hardness in Britain and average rainfall by area there's a close correlation between the two: the parts of the country that receive the most rainfall (the north/west) are also the areas with the softest water. DancesWithGrues (talk) 19:25, 26 April 2013 (UTC)