Understanding Water Efficient Toilets

MaP testing & WaterSense certification

In North America, we are lucky to have safe and easy access to treated water just by turning on the tap. Despite nearly 70 percent of the Earth's surface being covered by water, less than 1 percent is available for human use. According to the U.S. Environmental Protection Agency (EPA), the average American uses approximately 100 gallons of water per day at home. The EPA also cites toilets as the primary source of water use in the home, accounting for nearly 30 percent of an average home's indoor water consumption.

Being at the forefront of implementing better building practices, plumbing professionals and contractors are installing water-efficient fixtures and appliances in residential and commercial projects. Over the past decade, water-efficient toilets have been designed that rely on water-saving technologies to reduce the amount of water being used. For example, recent advancements have allowed toilets to use 1.28 gallons per flush, or less, which is 20 percent less water than the current federal standard. To ensure that products are meeting water-efficiency standards, testing and certification programs have continued to evolve.

The first water-efficiency standard to account for toilet flush volume was the Energy Policy Act of 1992. According to MaP, the generally accepted maximum flush volume for toilet fixtures in the U.S. during the 1980s was 3.5 gallons, or 13 Litres. With the introduction of the early 1.6 gal/6.0 Litre ultra-low-flow toilets (ULFTs) in the mid- to late-1980s, the Energy Policy Act of 1992 was set in place. With a few exceptions, this legislation required that by 1994, the flush volume of all toilet fixtures sold in the U.S. be no greater than 1.6 gal/6.0 Litres.

By 2002, a toilet "clog index" was developed through the joint efforts of Seattle Public Utilities (SPU), East Bay Municipal Utility District (EBMUD), and the National Association of Home Builders Research Center (NAHBRC). The "clog index" was determined through a testing protocol that flushed a varying quantity of sponges and paper wads. As the study progressed, it became clear that sponges were not a realistic representation of the real demand upon a toilet fixture. Furthermore, the work by the research center did not include identification of the minimum fixture performance level for a residential toilet.

Until 2003, there was no effective way to distinguish between superior, good and marginally performing toilets. MaP is a Maximum Performance scale that rates toilet efficiency and flush performance; it also provides detailed information on individual toilet characteristics. Only MaP tests replicate real-world demands put upon a toilet. MaP testing was initiated specifically to identify how well popular models performed using realistic fecal simulation. MaP incorporates the use of soybean paste and toilet paper to duplicate the real world demands put upon toilets. Each toilet is tested to failure – that is, soybean paste is repeatedly added to the toilet until the fixture can no longer remove it in a single flush. Toilets are assigned a MaP score representing the number of grams of solid waste that a particular toilet can remove completely from the fixture in a single flush.

Since its development, MaP has been a major driving force in the improvement of toilet flush performance in North America. The competitive pressure to improve fixture performance from the unacceptable levels of the 1990s, together with MaP as a vehicle to measure performance, have resulted in many hundreds of high-performance 21st century models. To date, 3,141 toilets from over 100 brands have been tested and listed in the MaP online database. Of these, 2,293 are certified to the U.S. EPA’s WaterSense specification for high-efficiency toilets (HETs).

WaterSense, a partnership program by the U.S. EPA, seeks to protect the future of our nation's water supply by offering solutions for people to conserve water by installing water-efficient products in residences and commercial buildings. While WaterSense was conceived in 2004 as a water-efficiency product labeling program for all products that come in contact with water for human use, WaterSense released its specification for tank-type HET’s in 2006. All products and services that have earned the WaterSense label have been certified to be at least 20 percent more efficient without sacrificing performance.

Upgrading to more efficient WaterSense labeled products can help save billions of gallons of water in the country every year. Today, 2,305 different toilet models meet the rigorous requirements of WaterSense and may be labeled with the WaterSense mark. The maximum flush volume of WaterSense tank-type toilet fixtures is 1.28 gallons (4.8 litres), with a special provision for dual-flush toilet models. A significant requirement for a WaterSense labeled high-efficiency toilet is that it must meet a minimum MaP threshold of 350 grams of waste removed from the toilet fixture in a single flush.

Many third-party testing organizations – such as, Intertek, CSA, and IAPMO – provide MaP testing and authorization to certify products to WaterSense standards. Although MaP testing and WaterSense certification are voluntary programs, states such as California, Georgia and Texas have passed laws that prohibit the installation of non-HET fixtures. Nationally, if all old, inefficient toilets in the U.S. were replaced with WaterSense labeled and MaP tested models, we could save 520 billion gallons of water per year, or the amount of water that flows over Niagara Falls in about 12 days. n


Jacques St-Denis is a building products/plumbing team leader based in Montréal, Canada. With over 25 years of experience at Intertek, Jacques is an expert in plumbing product testing and certification. As a leader of Intertek’s plumbing product testing services, he is responsible for creating testing plans, compiling product reports and interfacing with clients. In addition to reviewing Intertek’s testing ability, Jacques is on ASME/CSA/IAPMO standards committee for plumbing fixtures and fittings, as he also is a BNQ committee member for pipes and fittings. Jacques has a degree in Civil Engineering from Le Collège Montmorency in Laval, Québec. Visit www.intertek.com/building.

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