Toilet MaP (Maximum Performance) Testing
Toilet MaP Testing
Although virtually all toilet models sold in Canada and the U.S. meet both the flush volume and
performance requirements of the Canadian Standards Association (CSA) and the American
National Standards Institute/American Society of Mechanical Engineers (ANSI/ASME), there
remains some question as to whether models that meet the minimum certification requirements
meet the expectations of the consumer. What’s more, since certification testing offers only a
pass/fail grading, there is currently no easy way to distinguish between superior and marginal
toilet models available in the market.
Although other toilet performance studies have been completed, none of these have been
performed using test media as realistic as that used in this test, nor has a quantifiable
performance benchmark – based on the results of relevant medical data – been established.
The Maximum Performance (MaP) testing project was developed to identify how well popular
toilets models perform using a realistic test media, and to grade each toilet model based on this
performance. A soybean paste having similar physical properties (density, moisture content) to
human waste was used in combination with toilet paper as the test media. In addition to using a
realistic test media, all toilet samples are adjusted, where possible, to their rated flush volume
(typically 6 litres / 1.6 gallons) prior to testing to ensure a level playing field.
MaP Test (5th Edition)
Toilet Types and Technologies
There are hundreds of millions of toilets in the U.S., a majority of which use 3.5 gpf or more--some as much as 8 gpf. The Energy Policy Act of 1992 established national standards of 1.6 gpf. Below is an overview of toilet technologies and water usages.
Conventional gravity-flush toilets account for the vast majority of residential toilets sold today, as well as many commercial toilets. When flushed, a portion of the water flows to the holes at the toilet bowl rim to rinse the sides of the bowl and a portion flows into a siphon hole to initiate the siphon, which pulls water and waste out of the toilet bowl. In most 1.6 gpf toilets today, only about half of the water in the tank empties during a flush because the flapper closes before the tank is completely drained. By only partially emptying the tank, the full vertical head pressure of a larger tank is available for flushing force, yet water use is kept low. The latest most significant advance in these toilets is a larger flush valve at the bottom of the toilet tank, enlarged to 3 in. from 2 in. The real difference is in peak flow rate, 30 gpm vs. 50 gpm, for a faster flow and more effective flush.
Flapperless gravity-flush toilets. A true flapperless toilet replaces a flush valve at the bottom of the tank with a simple half-cylinder bucket at the top of the tank that holds exactly 1.6 gallons. When flushed, this half barrel dumps its load of water into the tank, initiating the flush. With no flapper, flapper seal, or chain, there is less to fail.
Pressure-assist flushometer-tank toilets have a separate, airtight (accumulator) tank inside the conventional-looking porcelain toilet tank. As this airtight plastic tank refills after flushing, air is pressurized above the water. During the flush cycle, this pressurized air rapidly pushes the water out of the tank. The water is delivered very quickly and at a high velocity--50 to 95 gpm .
Flushometer-valve toilets, common in commercial buildings, are tankless and use municipal water pressure to flush. The actual flush process is very much like that of flushometer-tank toilets, except that line pressure, rather than a separate tank, supplies the water.
Vacuum-assist toilets come mainly in two designs. The first and most common is a self-contained toilet that passively generates a modest vacuum to supplement the gravity flush. The mechanism is actually quite complex in which this modest vacuum force combines with the inherent siphonic action of the toilet bowl to enhance the "pull" on the toilet bowl contents, boosting the flush. The other type of vacuum toilet is very different and relies on a centrally located waste-collection tank that serves a large number of toilets (from about 20 to more than 2,000). Both the tank and the network of drainage piping are kept under negative pressure. When a connected toilet is flushed, a valve opens, allowing atmospheric pressure to force water and waste from the toilet bowl through the piping and into the vacuum tank. One brand of these "true-vacuum" toilets uses 0.4 gallons per flush.
Pump-assist toilets contain a small, submersible pump housed in the low tank behind the bowl, which forces water from the tank into the bowl during the flush.
Air-pressure toilets, some of which use just a half-gallon per flush, rely on an air compressor, located in a basement, garage, or utility room. A single compressor can serve a number of toilets.
Dual-flush toilets, which are very popular in Europe and Australia, provide two flush volumes depending on the waste to be flushed. The two different volumes are controlled by either lifting or pressing the lever, or, on some models, by two separate flush buttons. Most dual-flush toilets operate with a fairly conventional gravity-flush technology mechanism.
Composting Toilets. Even at 1.6 gpf, a typical toilet will be flushed five times per day and use about 3,000 gallons of water annually. Composting toilets can eliminate the use of potable water for flushing altogether. Composting toilets are primarily used in homes, but are are increasingly used in parks and nature centers. There have been a number of recent applications in commercial and institutional buildings, as well.
--Excerpted from "All About Toilets," Environmental Building News, January 2004, by Alex Wilson.
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