A flush toilet is a device intended for the disposal of human waste through drain pipes. There are many different designs of toilets that flush, and this method of waste disposal is considered highly hygienic and appropriate for areas in which human waste might make people sick, such as crowded urban areas. Most western toilets are flush toilets, and some squat toilets are also made to flush. Some flush toilet designs have features used to control the amount of water used, which can help keep water from being wasted.
People have known for a long time that leaving human waste in open air near living spaces can make people sick. Humans living as early as 31 B.C.E. discovered that water is an effective mechanism for removing waste from living areas. The flush toilet has been developing throughout history, and while the basic design has been somewhat solidified, features such as control over water use, bowl shape, and disposal technology continue to develop and change.
The basic design of a flush toilet usually involves a tank filled with water that quickly releases its contents into the toilet bowl when the flush mechanism is activated, then refills for the next flush. There are also tankless flush toilets that use water spurting quickly from a pipe to flush away waste. In both designs, both the water and waste exit the bowl through pipes and connect with a larger waste disposal system, which may be a sewer or septic system.
When using a flush toilet with a tank, the tank must be allowed to refill before the toilet can be flushed again. This can be a problem if the water does not succeed in removing waste from the bowl on the first flush. In public, this may prove an embarrassing problem, and people may leave waste in the bowl. This weak flushing problem is often a reason people do not choose to purchase flush toilets that use a low volume of water — although the volume of one flush may be low, when multiple flushes are required, more water ends up being used than with a normal toilet.
With solid waste, the flushing mechanism must be strong enough to evacuate all matter from the bowl. Liquid waste, on the other hand, can usually be flushed away with minimal amounts of water. Both for environmental and economic reasons, many people find that switching to a toilet with two flushing options is the best solution for human waste disposal.