The American Standard H2Option toilets introduce patent pending siphonic action technology that uses less water, eliminates more bulk and maintains a cleaner bowl. The dual flush activator saves on average 25% more water than standard bowls. The heavy flush utilizes 1.6gpf and the light flush utilizes 1.0gpf, saving the average family of 4 more than 17,000 gallons of water than an old 3.5gpf model or 3,650gallon savings over a standard 1.6gpf model. The H2Option is WaterSense listed.