Questions about Flush toilet
Short answers, pulled from the story.
Who invented the flush toilet?
No single person invented the flush toilet. Sir John Harington described and built an early forerunner in 1596, Alexander Cumming patented the S-trap in 1775, and Joseph Bramah produced what is considered the first practical non-manual flush toilet, patenting his design in 1778. Thomas William Twyford later invented the single-piece ceramic toilet in the 19th century. Thomas Crapper, despite popular legend, did not invent the flush toilet, though he held nine patents and popularized the siphon system.
What is the oldest known flush toilet in history?
In February 2023, archaeologists in China announced the discovery of what may be the world's oldest known flush toilet, found at the Yueyang archaeological site near Xi'an. The lavatory is approximately 2,400 years old and was unearthed among ancient palace ruins by researchers from the Chinese Academy of Social Sciences' Institute of Archaeology. Earlier examples of water-flushed latrines exist from the Neolithic period, including brick-built examples at the city of Uruk dating to 3200 BCE.
How much water does a modern flush toilet use per flush?
Modern low-flush toilet designs use 4.5 to 6 litres per flush. High efficiency toilets, or HETs, use 1.3 US gallons or less. Some newer pressure-assist designs use as little as 0.8 US gallons per flush, or 0.5 US gallons for the liquid-waste cycle in dual-flush models. Pre-1994 US residential toilets typically used 3.4 US gallons per flush, a figure the Energy Policy Act of 1992 reduced to 1.6 US gallons from 1994 onward.
Does water in a flush toilet really swirl differently in the northern and southern hemispheres?
No. The direction water swirls when a toilet flushes is determined by the angle of the bowl's rim jets during manufacture, not by the Coriolis effect. The Rossby number for a toilet bowl is on the order of billions, meaning the Coriolis force is far too weak at that scale to influence water direction. The toilet can be made to flush in either direction in either hemisphere simply by redirecting the rim jets.
What is a flushometer toilet and when was it invented?
A flushometer is a tankless toilet flush valve connected directly to a pressurized water supply line, allowing immediate reuse without a refill delay. William Sloan first made his flushometer design available in 1906. Flushometer valves are still widely installed in commercial restrooms worldwide and can be operated manually via a lever or button, or triggered automatically by an infrared sensor.
What is the difference between a siphon flush and a flapper-flush valve toilet?
A siphon flush system, invented by Albert Giblin and long mandated in the UK, uses no sealing washers and is therefore less prone to leaking, though it requires more force to operate. A flapper-flush valve, common in North American and continental European homes, is easier to operate but tends to develop leaks after a couple of years of use. UK research found that between 5 and 8% of toilets using flapper or drop valves are leaking, each losing between 215 and 400 litres on average per day.