Dual Flush Toilets - What You Need to Know & Why

Dual flush toilets are a great way to conserve water and make your bathroom more environmentally friendly. Flushing toilets is a major use of water and an expected part of bathroom hygiene, however, many toilets waste way more water than is necessary.

Dual flush toilets were invented by an Australian, Bruce Thompson in 1980. They are widely used in Australia, Asia and Europe and Israel. In some places it is mandatory that all new toilets are made that way.


Presently the US requires newer toilet designs to flush at 1.6 gallons per flush (gpf) maximum, however there is no widespread requirement for the dual flush option, which is lower volume flush. It's too bad we don't push dual flush toilets more to save water.  Perhaps we feel it fringes upon peoples freedom to require something like this.  To conserve water though it would make sense to require new toilets to have this feature

One is a full flush for solid waste and the other ½ flush is for liquid waste. Dual flush toilets are available for purchase in the US, but they just aren't as commonplace as in some other countries.

If you aren't in the market for a new toilet, you can purchase a retrofit conversion kit and install it in your existing toilet. Imagine how much water and money schools, and multi-family dwellings could save if they installed dual flush retrofit conversions.

For the ultra economic, no frill way to save water you can fill a water bottle or slightly larger plastic bottle with sand or little rocks, put the lid on and put it in the toilet tank away from the interior components to take up some of the space the water normally occupies. The water will still fill to the same line in the tank but will be less water than before you put the bottle in the tank.

Early water saving toilet models occasionally had some problems with flushing, however since then the design of the trap and flushing mechanism has improved to where they are becoming more popular in America. In other words maybe you heard about some dissatisfaction in the past with these type of toilets, however, that is no longer a reason to avoid them now, because now they work better. 

High efficiency toilets (HETs) can be single flush or dual flush. Some are power-assisted or pump-assisted or vacuum-assisted. The maximum performance scores (MaP) range from 250 to 1100. The EPA Water Sense Program requires 350 MaP as the minimum standard. That means the toilet must be able to flush 350 grams of waste in one flush. A MaP of toilet fixtures can be found here. http://www.cuwcc.org/WorkArea/showcontent.aspx?id=14058

Dual Flush toilets use a larger trap to remove waste with less water pressure. The larger trap helps to prevent your toilet from clogging! Yes say goodbye to clogged overflowing toilets!  Now that you have heard that good news don't forget to call your water provider or municipality to see if they offer a rebate for purchase of a high efficiency toilet.

When you are shopping for a new toilet, first narrow it down to ones that are EPA Water Sense compliant. Then decide if you want a one or two piece toilet. One piece may be easier to clean, but more expensive and harder to install. Toilet bowls also come in two heights, and two shapes - either round or elongated. With changes in the trap size and shape most gravity toilets today work as well as the pressure-assisted toilets. Pressure-assisted toilets have a louder flush.

By purchasing a dual flush toilet you are conserving water, a precious resource. Less than 3 percent of the water on earth is fresh water. We can't easily reach most of that water because it it located in glaciers, icecaps or below the earth. You can do your part to conserve water by purchasing a dual flush toilet or installing a dual flush conversion retrofit in your existing toilet and telling others about it.  Some people have never heard of them so lets help educate the public about the benefits of using a dual flush toilet.

For information about energy efficiency and conservation in your home please see  http://www.homes-energy-efficient.com/