Passenger train toilet
Many passenger trains (usually medium and long-distance) have toilet facilities, often at the ends of carriages. Toilets suitable for wheelchair users are larger, and hence trains with such facilities may not have toilets in each carriage.
The traditional method of disposing human waste from trains is to deposit the waste onto the tracks using what is known as a hopper toilet. This ranges from a hole in the floor to a full-flush system (possibly with sterilization). The 'hole in the floor' (also known as a drop chute toilet) system is still in use in many parts of the world, particularly on older rolling stock. The principal drawback is that it can be considered crude or unhygienic – it litters railway lines and can produce health risks if the train is passing over a public waterway. Passengers may be discouraged from flushing or using toilets while the train is at a station. In the United States, Dvořák's "Humoresque Number 7" became the setting for a series of mildly scatological humorous verses, regarding passenger train toilets, beginning:
Passengers will please refrain
From flushing toilets while the train
Is standing in the station (I love you)...
Generally the problem is unavoidable, although toilets may be automatically locked when the train pulls into a station.
Properly designed drop chute toilets will draw air like a chimney, pulling air through the lavatory door vents and down and out through the toilet, reducing odor.
Chemical retention tank
Chemical retention tanks are usually included on newer carriages and railcars in wealthier and more densely populated parts of the world. One issue is that the tanks need to be regularly emptied, often at a terminal station or prolonged stop-over. If a train is required in service again within too short a period, the tanks may not get emptied. In this case, toilets may back up, which can result in toilets being closed. Carriages may have less "in service" time if fitted with chemical retention tanks.
Some trains may have composting toilet tanks, which use bacterial action to break down solid and liquid waste before releasing it to the trackbed by way of a chlorine sanitizing tank.
The traditional hole in the floor system, operated by a pedal
DO NOT USE the toilet while the train is stopped at the station notice in Polish, German, French and English used by Polish State Railways.