What Is WaterSense Certification for Toilets?

What is WaterSense?

WaterSense is a partnership program run by the U.S. Environmental Protection Agency (EPA). It labels products that meet EPA criteria for both water efficiency and performance. The program covers toilets, showerheads, faucets, irrigation controllers, and other water-using products. For toilets, the label means the model has been independently certified to use less water than the federal standard while still performing well.

The EPA notes that toilets are the main source of water use in the home, accounting for nearly 30 percent of an average home's indoor water consumption. Older, inefficient toilets that use as much as 6 gallons per flush are a major source of wasted water. WaterSense labeled toilets address this by using 1.28 gallons per flush or less, which is 20 percent less water than the current federal standard of 1.6 gallons per flush.

WaterSense is voluntary. Manufacturers choose to submit their toilets for certification. Only models that pass third-party testing and meet EPA's criteria can carry the label. When you see the WaterSense label on a toilet, it means the product has been verified, not just claimed, to be efficient and effective.

The WaterSense specification for toilets

The EPA's WaterSense Specification for Tank-Type Toilets sets the technical requirements for certification. Version 1.2 is currently in effect. It was released on June 2, 2014. The EPA released a major revision, Version 2.0, in May 2024, but has paused its effective date. Version 1.2 remains in effect until further notice.

Under Version 1.2, a toilet must use no more than 1.28 gallons per flush on average. For dual-flush toilets, the effective flush volume is calculated based on the full-flush and reduced-flush volumes, weighted by the assumption that the reduced flush is used more often. The result must still be 1.28 GPF or less.

Version 2.0 would change the approach for dual-flush toilets. It would eliminate the effective flush volume calculation and instead set the same maximum flush volume of 1.28 gallons for both single-flush toilets and the full-flush mode of dual-flush toilets. Since Version 2.0 is paused, buyers should check which specification a current model meets, though all labeled models must meet at least Version 1.2.

Performance testing: does it really flush?

The key difference between WaterSense and simple low-flow toilets is the performance requirement. In the 1990s, some low-flow toilets earned a poor reputation because they required double flushing. The EPA worked with stakeholders starting in early 2006 to develop performance criteria alongside water efficiency criteria. These criteria were later adopted into the national plumbing standard, ASME A112.19.2/CSA B45.1.

All WaterSense labeled tank-type toilets must comply with and be independently certified to meet the same rigorous performance requirements as standard toilets. These include four main tests:

Ability to flush testing media of different sizes and densities, including floating and sinking media. Ability to clean the surface of the bowl. Ability to transport waste media through a drainline. Ability to clear soybean paste test media and toilet paper, meant to represent human waste, from the bowl.

• Mixed testing media flushability: the toilet must clear a mix of floating and sinking test media.
• Bowl surface cleaning: the toilet must rinse waste from the bowl surface.
• Drainline waste transport: the toilet must push waste media through a drainline.
• Waste extraction: the toilet must clear soybean paste and toilet paper from the bowl.

How much water does WaterSense save?

The EPA estimates that replacing old, inefficient toilets with WaterSense labeled models can reduce water used for toilets by 20 to 60 percent for an average family. That translates to nearly 13,000 gallons of water savings per home every year. The EPA also notes that, nationally, replacing all old toilets in the United States could save more than 260 billion gallons of water per year.

The exact savings depend on the age and efficiency of the toilet being replaced. A toilet from the 1980s or 1990s might use 3.5 to 6 gallons per flush. Moving from 6 GPF to 1.28 GPF is a dramatic reduction. Even replacing a 1.6 GPF toilet with a 1.28 GPF model saves 20 percent per flush.

Dual-flush WaterSense toilets can save even more. By choosing the reduced flush mode for liquid waste, you use a smaller volume of water. The effective flush volume calculation in the WaterSense specification accounts for this, and a dual-flush model that meets the 1.28 GPF effective volume can deliver lower real-world water use than a single-flush model at the same rated volume.

What the label does and does not mean

The WaterSense label is a certification of efficiency and performance, not a rating of quality or luxury. A labeled toilet is certified to use no more than 1.28 gallons per flush and to pass the four performance tests. It says nothing about comfort height, bowl shape, finish durability, or noise level.

WaterSense labeled toilets are available in a wide variety of styles and price points. You can find them as one-piece and two-piece models, with round or elongated bowls, and at standard or chair height. Many have dual-flush mechanisms. If you are looking for a water-efficient toilet, the label is a reliable starting point that does not force you to compromise on other features.

The label also does not mean the toilet is right for your plumbing. Drainline carry, trapway size, and rough-in dimensions vary between models. A WaterSense toilet with a longer trapway or larger trapway diameter might handle your drain distance better. Check the toilet trapway explained article to understand how waste transport works, and confirm the rough-in distance matches your floor flange before you buy.

How to choose a WaterSense toilet for your home

Start by confirming the rough-in distance. Most homes in the United States use a 12-inch rough-in, but 10-inch and 14-inch are also common. Measure from the wall behind the toilet to the center of the floor bolts. See the how to measure rough-in guide for step-by-step instructions.

Next, decide on bowl shape and height. Round bowls save space in small bathrooms, while elongated bowls offer more comfort. Chair height, also called comfort height, is easier to stand from and is a common choice for adults. The round vs elongated and toilet seat height guides explain the trade-offs.

Then choose between single flush and dual flush. A single-flush WaterSense toilet uses 1.28 gallons for every flush. A dual-flush model uses less for liquid waste and 1.28 gallons for solid waste. The dual flush toilets article covers how these mechanisms work and which situations suit each type.

Finally, consider flush performance beyond the label. The WaterSense test uses a 2-inch test media and soybean paste. It does not test every real-world scenario, such as large solid waste or heavy toilet paper use. Models with a wider trapway or a larger bowl water surface area tend to handle these situations better. The MAP testing article explains the independent flush performance test that measures grams of waste cleared in one flush.

What to pick for your use

Questions

Is WaterSense the same as Energy Star?

No. WaterSense is an EPA program for water efficiency, while Energy Star covers energy efficiency. A toilet cannot earn an Energy Star label. WaterSense is the relevant certification for toilets.

Do WaterSense toilets flush as well as 1.6 GPF toilets?

The EPA states that design improvements have allowed toilets to use 1.28 gallons per flush or less while still providing equal or superior performance. WaterSense labeled toilets are independently certified to meet the same performance requirements as standard toilets, including waste extraction, bowl cleaning, and drainline transport tests. In practice, a 1.28 GPF WaterSense toilet can perform better than an older 1.6 GPF model due to improved bowl and trapway design.

What is the effective flush volume for dual-flush toilets?

Under WaterSense Version 1.2, the effective flush volume is a weighted average of the full-flush and reduced-flush volumes. The EPA assumes the reduced flush is used more often. The result must be 1.28 gallons or less. Version 2.0, which is currently paused, would require both the full-flush mode and single-flush toilets to use no more than 1.28 gallons per flush.

How can I tell if a toilet is WaterSense certified?

Look for the WaterSense label on the product packaging or on the toilet itself. You can also search the EPA's WaterSense product database, which lists certified models. If the model name includes a WaterSense logo or the spec sheet mentions WaterSense certification, it has passed third-party testing.

Are WaterSense toilets more expensive than regular toilets?

WaterSense labeled toilets are available at a wide variety of price points. The EPA notes that in many areas, utilities offer rebates and vouchers that can lower the price of a WaterSense labeled toilet. Over time, the water savings can offset the purchase price. The EPA estimates an average family can save nearly 13,000 gallons per year, which reduces water bills.

Is WaterSense certification required by law?

No. WaterSense is a voluntary program. The federal standard requires toilets to use no more than 1.6 gallons per flush, but it does not require the WaterSense label. Some states and local jurisdictions have adopted the 1.28 GPF limit for new construction, but the WaterSense label itself is optional. Check your local plumbing code to see if there are flush volume requirements in your area.