What Is a Dual Flush Toilet?

Dual Flush Toilet

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Toilets might seem like a staid technology, but they're continually evolving. One of the best innovations, the dual flush toilet, responds to a growing awareness in many places: water conservation.

It's estimated that over one-quarter of the water used in homes is used by toilets. Shrinking that number goes a long way toward reducing household use, plus it lightens the community's demands on its surface and groundwater supplies.An easy way to do that is by installing a dual flush toilet.

What Is a Dual Flush Toilet?

A dual flush toilet has two separate user-controlled operations for flushing away liquid or solid waste. Less water is used for liquid waste and more water is used for solid waste.

What a Dual Flush Toilet Is

A dual flush toilet gives the user the option of flushing either a low amount of water (0.8 GPF on some models or 1.1 GPF on other models) or a greater amount of water (1.28 on some or 1.6 gallons per flush or GPF on others). The lower amount of water is adequate for flushing liquid waste. A greater amount of water is necessary for flushing down solid waste. Operations are usually controlled by a single control (bifurcated into two halves) on top of the toilet tank.

How a Dual Flush Toilet Differs From Toilets

Dual Flush
  • Two flushes for separate uses

  • Two controls

  • Solids flush: 1.28 or 1.6 GPF

  • Liquids flush: 0.8 or 1.1 GPF

Single Flush
  • One flush for all uses

  • One control

  • Solids flush: 1.28 GPF

  • Liquids flush: 1.28 GPF

Older toilets prior to 1994 used vastly more water than today's toilets: from 3.5 GPF to as much as 7 GPF. Later, federal mandates restricted that number to 1.6 GPF. Though that restriction is still in place, more recent toilet advancements have decreased flush volume to 1.28 GPF.

Toilets with a 1.28 GPF flush volume are certified by the EPA's WaterSense program and can save a household about 13,000 gallons of water per year.

Dual flush toilets' low volume flush is often called a "half flush." Rarely is this the case. More often, a high volume flush of 1.6 GPF is coupled with a low volume flush of 1.1 GPF (nearly 69-percent, not 50-percent). In the case of 1.28/1.0 GPF dual flush toilets, the difference in flush savings is even less.

Why You Might Want a Dual Flush Toilet

  • You care about your environment: A community's widespread use of dual flush toilets can aid with overall water conservation.
  • You want to save water and money: If you pay for your municipal water, you will save on your water bill by installing a dual flush toilet. How much you will save depends on how much you pay per centum cubic feet (CCF) of water, a unit equal to 748 gallons.
  • You can commit to correctly using dual flush toilets: Everyone in the household must commit to only using low flush mode for liquid waste. Routinely using high flush mode for liquid waste negates the water and cost savings.

Tip

Dual flush toilets were first developed for widespread consumer use in 1980 by the Australian sanitary products company Caroma.

Considerations When Buying a Dual Flush Toilet

How Does the Dual Flush Work?

How the dual flush is activated can be a hindrance for some users. Cryptic markings take some learning. Children may not be tall enough or strong enough to push buttons located on the top of the tank.

Some dual flush toilets work counterintuitively. They have a side-mounted lever that produces a full flush when you quickly press and release the handle. Pressing and continuing to hold the handle down activates a low-volume flush.

If mobility is an issue, reaching the top of the tank might be difficult for some, especially in smaller bathrooms or guest bathrooms.

How Much Water Does It Use?

In most cases, you'll either purchase a 0.8/1.28 GPF or a 1.1/1.6 GPF toilet. The latter choice produces a stronger flush.

But depending on your pattern of use, this higher-volume toilet might average out to use as much or even more water than a single flush WaterSense-certified toilet.

While still available, single-flush 1.6 GPF toilets are increasingly more difficult to find. So, if you use the 1.1/1.6 GPF toilet exclusively in high volume mode, that's essentially what you've got: a 1.6 GPF toilet.

Dual flush toilets produce benefits only when every liquid waste flush uses the lower water mode.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Indoor Water Use in the United States. EPA WaterSense

  2. Water Sources. Centers For Disease Control

  3. Residential Toilets. EPA

  4. Our Story. Caroma