The oldest flush toilets from the 1950s used about 7 gallons of water per flush. Over the decades this number lessened to 5.5 in the 1970s, then to 3.5 gallons in the 1980s and finally in 1995, the federal government decreed that all toilets must be of the low-flow variety and use no more than 1.6 gallons of water per flush.
The idea, of course, was to conserve water. A noble goal but one that is unworkable if the toilet does not completely remove the waste and the user must double-flush. To resolve any issues with poorly performing toilets, the industry developed the power flush toilet. This modern version of the standard flush toilet meets all government regulatory requirements but also functions reliably and completely removes any waste with a single flush.
How A Standard Flush Toilet Operates
A standard toilet operates by introducing a quantity of water (the above mentioned 1.6 gallons) from the reservoir tank. As the water fills the lower bowl, it reaches and then passes the height of the “trap” in the back of the toilet. One this happens, gravity pulls the water into the main drain and a suction effect pulls the waste and the remaining water into the drain. Sometimes, however, this process is not sufficiently powerful to remove all of the waste.
The Power Flush Advantage
A power flush toilet uses the same principle but augments suction effect with some additional pressure. Inside the upper reservoir of a power flush toilet is another tank that holds the reserve water. This tank is air tight. As it fills with water, the air inside is compressed and a substantial amount of pressure is built up. When the toilet is flushed, the pressurized water is released and toilet is cleaned. Power flush toilets can thus remove considerably larger amounts of waste and move it further down the drain line. The power flush toilet therefore meets the goal of water conservation while still easily and reliably removing waste materials.