An HET is defined as a toilet that flushes at 20 percent or better below the standard 1.6 gpf level.  All new toilets are required by federal law to use 1.6 gallons per flush (gpf) or less. The plumbing industry is introducing many new technologies and toilet fixture models that reduce effective flush volumes well below the mandated 1.6 gallons per flush (gpf) maximum.  HET’s have been common throughout Europe, Australia, Asia, and South America for years, and are now commonly found in the U.S. marketplace.

• A dual flush toilet is a toilet that allows the user to choose between a "short flush" that uses between 0.6 and 1.0 gallons when there is only liquid waste in the bowl to be flushed, and a "full flush" using 1.6 gallons when solid waste is to be flushed.  Many new models have a combined or average flush volume of 1.2 gpf.

•  The 1.0 gpf pressure-assist single flush toilet uses compressed air to create a powerful flush to push the waste out of the bowl.
   
• Gravity flush toilets is the most common type of toilet found in homes.  Gravity flush HET’s are designed to flush with 1.3 gpf or less, and use the weight of the water along with gravity to pull the waste from the bowl.

What is WaterSense? 

WaterSense is the new rating system (similar to Energy Star) that offers consumers a simple way to make product choices that use less water with no sacrifice to quality or product performance from the U.S. Environmental Protection Agency.  EPA has certified 64 high-efficiency toilets with the WaterSense label.  EPA will continue to add more products to this HET list.