WaterSense toilets and the water a flush uses

Toilets are the main source of water use inside a home. How much each flush uses depends on when the toilet was made. Older, inefficient toilets can use as much as 6 gallons per flush. The current federal standard is 1.6 gallons. Design improvements now let toilets flush with 1.28 gallons or less and still work as well or better.

What the WaterSense label means

A toilet with the WaterSense label uses 1.28 gallons per flush or less, 20 percent less water than the federal standard. Each labeled model is independently certified to meet criteria for both water efficiency and flushing performance. Only toilets that complete the third-party certification can carry the label.

The performance tests

The low-flow toilets of the 1990s sometimes needed a second flush. The WaterSense performance criteria were written to answer that, and they've since been adopted into the national plumbing standard. Every labeled tank-type toilet is tested for:

• Flushing mixed media. Clearing test material of different sizes and densities, some that floats and some that sinks.
• Bowl cleaning. Washing the surface of the bowl.
• Drainline transport. Carrying waste through the drain line.
• Waste extraction. Clearing test media and toilet paper from the bowl.

Dual-flush toilets

A dual-flush toilet has two buttons or a split handle. The reduced flush uses a smaller volume of water for liquid waste, and the full flush handles the rest.

The water a leak wastes

A flush uses water only when you press the handle, but a leaking toilet uses it all day. Household leaks can waste 180 gallons a week, and toilets are often the culprit. Most toilet leaks come from an old or worn flapper, the rubber, plastic or silicone seal that controls the flow of water into the bowl. To check for a silent leak, put a few drops of food coloring in the tank and wait 10 minutes. If color shows up in the bowl, the toilet leaks. Flush afterward so the dye doesn't stain.

An annotated example

What to do next

Test each toilet for a silent leak with a few drops of food coloring in the tank. Record each toilet's make and model in your home records. Find household water leaks with the meter and food coloring covers the rest of the house.