Modern air travel would not be possible without the advent of the jet propulsion engine. A jet is a high-velocity stream of fluid that is used for a variety of engineering applications. In the case of a jet engine, incoming air is compressed to pressures over 100 psi, mixed with fuel and combusted to create up to 9,000 pounds of thrust. Similarly, many modern conveniences would not be enjoyed without the advent of the siphon-jet toilet. Using similar technology, a high-velocity stream of water is directed near the base of a porcelain-coated bowl to initiate the evacuation of a solid/liquid mixture through an engineered trapway with a final siphonic phase action.
A siphon is defined as a “tube bent to form two legs of unequal length by which a liquid can be transferred to a lower level over an intermediate elevation by the pressure of the atmosphere in forcing the liquid up the shorter branch of the tube immersed in it while the excess of weight of the liquid in the longer branch when once filled causes a continuous flow.” In the case of a toilet, it consists of a trapway designed into the molded clay, vitreous coated casting. The trap is designed to hold a specific volume of water and needs to be big enough to pass an expected amount of solid/liquid biomass. The high water mark, based on third-party testing, is 1,000 grams for commercial toilets. A natural question is: “Why not just make the trapway as big as possible, then toilets would never clog?” The bigger the trapway, the more water it takes to keep it full and maintain a siphon during flushing.