The pressure assisted toilet relies on a pressure vessel inside the china tank that stores and compresses air and water. This system, when filled, is now energized and when flushed, water is sent at a high rate of speed to the bowl. A large percentage of the 1.6 gallons of water being used is delivered directly to the jet at the bottom of the bowl. This jet is very powerful. It is the force that removes the waste. This noise is part of the design and will last for only 3 seconds.