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All About Toilets

Today's market has vast resources.

Alex Wilson with research assistance from Mark Piepkorn -- Interior Design, 4/14/2005 12:00:00 AM

Just when you thought it was safe to pick up a copy of EBN, here comes an article on toilets! Brace yourself for details on the use of cultured soybean paste to more accurately simulate human waste in toilet performance testing…for details on pushing vs. pulling waste from toilets …and almost certainly for more than you ever wanted to know about toilets.

Following a little historical background on toilets, this article will focus on water conservation. We’ll review statistics on water consumption by toilets, describe technologies used to flush toilets with relatively little water, address retrofitting older toilets, and examine toilet performance. Toilets for both commercial and residential buildings will be covered.

A Short History of Toilets

When our ancestors began leaving their agrarian land base for cities, disposing of human waste became an important issue. The idea of flushing human wastes away using water goes back more than 4,000 years. In the Harappa civilization of Western India in 2500 BC, many houses had toilets with waterborne drainage channels covered with fired brick. During the period of King Minos on the Isle of Crete around 1700 BC, the rulers had extravagant bathrooms with both hot and cold water and a means to flush away human wastes. The sophisticated public latrines of Ancient Rome also used flowing water to carry away wastes.

Photo: Paul Brians, Washington State University, www.wsulibs.wsu.edu
Photo: Steve Harding, www.sewerhistory.org

But after the fall of the Roman Empire, advances in sanitation ceased. Chamber pots and open cesspools prevailed in densely populated cities. “Night soil” was dumped into street gutters, and many rivers became open sewers. In the hot summer of 1859, the River Thames became so pungent that Parliament was suspended! But by this time, major advances were being made with toilets.

In England in 1596, Sir John Harrington, godson to Queen Elizabeth I, designed and built the first flush toilet, but he was so ridiculed by his peers for this absurd device that he gave up his career as an inventor. Further progress with flush toilets would wait almost two centuries—until 1775, when Alexander Cummings reinvented the “water closet” and introduced the first S-trap to keep sewer odors from escaping through the toilet. Following a century of incremental improvements, in 1885 Thomas Twyford revolutionized toilet design by replacing the metal and wood contraptions seen previously with an all-porcelain design.

On the other side of the Atlantic, Americans began leading the charge in the late 1800s. John Randall Mann patented a three-pipe water closet in 1870, developing a method to utilize the suction force of a siphon to aid the flush. Thomas Kennedy followed with a method of using two pipes to simultaneously rinse the rim of the toilet and start the siphon (the basic operation of today’s gravity-flush toilets). Literally hundreds of toilet patents were issued between 1890 and 1930.

In a history of toilets, it is important to point out that Thomas Crapper did not invent the flush toilet. Born in 1836, Crapper had an active career in the English plumbing industry from 1861 to 1904, and he patented some minor improvements in drains, pipe joints, and water closets. But the “Silent Valveless Water Waste Preventer” (a siphon-discharge toilet) that he is often credited with inventing was actually developed by Albert Giblin. Crapper marketed this device under his name, however, and World War I soldiers passing through England came to identify the “Crapper” with water closets—a term that has certainly stuck (in some circles).

Toilets and Water Conservation

There is no disputing the fact that toilets consume a lot of water. In North America, nearly all of this flush water starts as clean, drinkable water. The American Water Works Association (AWWA) Research Foundation examined water use in approximately 1,200 homes in 14 North American cities and found that an average household uses approximately 146,000 gallons (550,000 l) of water annually, 42% indoors and 58% outdoors. In households where water-conserving plumbing fixtures have not been installed, toilets use an average of 20.1 gallons (76 l) of water per day, or 26.7% of total indoor water use. In homes with water-conserving fixtures, toilets use an average of 9.6 gallons (36 l) per day, or 19.3% of the total—though plumbing leaks account for another 10–14% of water use, and much of that is due to toilets.

Troubling Toilet Leaks

A 1993 study by AWWA found that up to 25% of toilets in U.S. homes leak. These leaks can range from a few gallons per day to more than 500 (1,900 liters). Until a toilet leak reaches a rate of about 100 gallons (400 liters) per day, it may not even be audible (depending on the toilet and piping)!

Toilets leak primarily because of worn or improperly fitted flapper valves, which often last only 5 to 10 years. Other culprits may include improper toilet adjustment (if the toilet tank level is adjusted too high, water may spill into the overflow pipe), incorrect replacement parts, and damage to elastomeric materials from chemicals. Time-release chemicals in automatic toilet bowl cleaners are particularly problematic, especially when a toilet isn’t used for several weeks and the chemical concentrations build up. Chloramines and other chemicals in municipal water systems can also degrade certain elastomers.

Interestingly, some gravity-flush toilets leak only at night. That’s because fewer people are drawing water at night, and municipal water pressure can increase system-wide—sometimes by more than 25%. This pressure increase can cause water creep, in which the water level in the toilet tank rises (sometimes by a half-inch [12 mm] or more). If that water level rises enough, it may spill into the overflow pipe. Fortunately, this problem is easy to fix by adjusting the float ball position.

There are several ways to find toilet leaks. If you can’t hear the leak or see a slight rippling in the toilet bowl due to inflowing water, the best option is to put a small amount of food coloring into the toilet tank. If that dye makes its way into the toilet bowl, there is a leak. It’s a good idea to periodically test all gravity-flush toilets in a house or commercial building for leaks. Pressure-assisted, flushometer toilets are much less likely to develop leaks, and if they do, those leaks are likely to be more noticeable.

Repairing leaks usually involves replacing the flapper valve or entire flush mechanism. At this time a water-conserving, early-closure flapper valve can be installed on a high-volume toilet. But a leaking older toilet is also a good excuse to finally replace it with one of the top-performing 1.6 gallon (or lower) toilets.

Toilet manufacturers in the U.S. gradually began to reduce the water consumption of toilets in the 1960s. By 1980, the water consumption of most toilets had dropped from an average of 5–7 gallons per flush (gpf) in the 1950s to 3.5 gpf (from 19–26 to 13 lpf). A push to go well beyond that level of water use emerged in the 1980s. Meanwhile, some European countries were well ahead of the U.S. In 1972, Sweden, struggling with polluted estuaries around Stockholm caused by excessive discharges from sewage treatment plants, instituted the first regulations to limit the amount of water used for flushing toilets—establishing the maximum flush at 6 liters (1.6 gallons). During the ’70s, imported four- and six-liter Swedish toilets made by Ifö became popular in the U.S., especially among homeowners who had septic system problems.

The first statewide restrictions on the water use of toilets in the U.S. were adopted in 1987 (to become effective in March 1989)—not in the arid southwest, but in Massachusetts. This law, establishing a limit of 1.6 gpf (6 lpf) for most toilets, was followed rapidly by similar laws in other states. By the early ’90s, at least 17 states had 1.6 gpf regulations in place. Meanwhile, water conservation experts, as well as many manufacturers who were struggling to produce different toilets for different markets, asked the federal government to step up to the plate and establish national regulations on toilets. The Energy Policy Act of 1992, which went into effect in January 1994, established national standards of 1.6 gpf and superseded state regulations. Manufacturers could now produce toilets to a single water conservation standard.

While no state or local authority can establish stricter water conservation standards in the U.S. without approval from the U.S. Department of Energy, at least five countries currently go beyond the 1.6 gpf standard. Australia, Denmark, Finland, Norway, and Singapore have flush-volume limits ranging from 0.8 to 1.2 gallons (3.0–4.5 l).

Flush Toilets Today

Flush toilets have come a long way in the past few decades. The all too common problems of double flushing, blockages, and extensive “streaking” experienced with early 1.6 gpf toilets are now much less frequent. Manufacturers use a variety of approaches to achieve good performance with 1.6 gallons (6 l) of water—or less. These technologies are described below.

Conventional gravity-flush toilets

Gravity-flush systems account for the vast majority of residential toilets sold today, as well as some commercial toilets. When most gravity-flush toilets are flushed, a portion of the water flows to the rim 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. The flush is powered by gravity—because the tank is positioned above the bowl. A flapper valve at the bottom of the toilet tank controls the flush. The tank refills through a ballcock or fill valve, which closes when the water reaches the proper level—usually controlled by a float ball. As the tank refills, a portion of the refill water is diverted through a tube to refill the toilet bowl.

Better gravity-flush toilets

Many advances have been made to the gravity-flush toilet to ensure adequate performance with reduced water use. Bowls have been redesigned using advanced computer modeling to achieve better waste removal. Trapways (the S-shaped pipe through which the toilet bowl drains) have been redesigned. In most 1.6 gpf toilets today, only about half of the water in the tank empties during a flush; 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. In addition, because the cold refill water is diluted, condensation on the outside of the tank (sweating)—a common summertime problem in more humid regions—is minimized.

A significant advance pioneered by Japanese toilet manufacturer Toto is a larger flush valve at the bottom of the toilet tank, which speeds the flow of water into the bowl (see illustration).

Toto revolutionized the gravity-flush toilet design with the 3” flush valve. The Ultramax is consistently
one of the top-performing toilets.

Adapted from schematic by Toto, the industry standard flush valve for nearly 100 years has been 2” (50 mm) in diameter, resulting in a peak flow rate of no more than 30 gallons per minute (gpm) (135 lpm). In 1997, Toto introduced a 3” (75 mm) flush valve, speeding the peak flow rate to about 50 gpm (230 lpm). The faster flow means a shorter duration and more effective flush.

In 2003, American Standard followed suit by introducing the Champion with a 3” flush valve. While the company calls this a “flapperless” design, it still has a flush valve seal that works much like a flapper. The company also claims to have the largest-diameter trapway in the industry at 2 &SUPER>3&/SUPER>⁄ ₈” (60 mm).

Another recent advance is a super-smooth porcelain surface used by a number of toilet manufacturers to improve flow, reduce sticking, and ease cleaning.

Flapperless gravity-flush toilets

Niagara Conservation Corporation markets a true flapperless toilet.

The Niagara Flapperless toilet uses a very different flush mechanism than other gravity-flush toilets. Turning the handle pivots a trough of water for the flush supply. Source: Niagara Conservation

In place of a flush valve at the bottom of the tank, the toilet has a simple half-cylinder “bucket” at the top of the tank that holds exactly 1.6 gallons. When the toilet is flushed, this polypropylene bucket dumps its load of water into the tank, initiating the flush (see illustration). Because there is no flapper, flapper seal, or chain, there is less to fail; the product has performed well on many, though not all, independent tests of flush performance.

Pressure-assist flushometer-tank toilets

When 1.6 gpf toilets first entered the market, many did not perform well. As a result, a number of technologies were introduced to provide a more forceful flush with the allowable water use. One of these technologies is the pressure-assist toilet using a flushometer tank.

Sloan’s Flushmate IV pressure-assist flush mechanism provides excellent flush performance using just 1.0 gallons (4 liters) of water. Source: Sloan Valve Co.

This basic system is currently manufactured by two companies—Sloan Valve Company (Flushmate®) and Geberit/The Chicago Faucet Company (PF/2® Energized Flush®)—and incorporated in at least a dozen toilet models from many leading toilet manufacturers.

Here’s how the flushometer pressurized-tank system works: There is a separate, airtight (accumulator) tank inside the conventional-looking porcelain toilet tank (see illustration. 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 (225–430 lpm)—with a sudden, loud “whoosh.” After the pressurized tank empties, the flush valve is sealed tightly—the pressure provides a tighter seal than with gravity-flush toilets (25 times the force, according to Geberit), so the likelihood of leakage is greatly reduced. Condensation is not a concern with flushometer-tank toilets, because of the double-tank configuration.

While both Sloan and Geberit produce 1.6 gpf flushometer-tank systems, Sloan recently raised the bar with the introduction of the Flushmate IV system, which uses just 1.0 gallons (4 l) per flush. This system is now available in toilets from three manufacturers: Mansfield, St. Thomas, and Mancesa, with a fourth, Gerber, to offer it starting in 2004. Paul DeBoo of Sloan told EBN that the new Flushmate IV is 18–20% quieter than the original Flushmate, while using 33% less water.

In October 2003, a third manufacturer announced a pressure-assist flush mechanism: the Chinese company WDI International. WDI produces the EcoFlush system that provides dual-flush capability in a pressure-assist design (see further discussion on dual-flush toilets on page 10). The EcoFlush uses 1.6 gpf or 1.1 gpf, depending on whether solid or liquid wastes have to be flushed. The first manufacturer to incorporate this mechanism into its toilets will be Mansfield, with the Quantum EcoFlush, which will become available in the first quarter of 2004.

Flushometer-valve toilets

Most larger commercial buildings do not use tank-type toilets. A flushometer-valve toilet delivers the necessary force for flushing using only the municipal water pressure. 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. Fairly high water pressure is required for this type of toilet, and it usually has to be supplied by a 1” (25 mm) plumbing line. It provides a quick flush and rapid recovery but is also quite noisy.

A specialized type of flushometer-valve toilet is the “blowout-valve” toilet. This rugged, rear-outlet toilet, is the only type of toilet exempted from the federal 1.6 gpf limit; these can still be sold with water use of 3.5 gpf (though approximately 25 state or local code jurisdictions prohibit these). Blowout toilets, which once used up to 8 gallons (30 l) per flush, are used primarily in locations subject to high abuse, such as prisons and airports, according to Amy Vickers in her Handbook of Water Use and Conservation, and the number of these toilets installed is relatively small.

Vacuum-assist toilets

Instead of pushing water through a toilet to induce the flush (as occurs with gravity-flush and pressure-assist toilets), some toilets use a vacuum to help pull the wastes out of the toilet bowl. Two different approaches are typical with vacuum toilets. Most common in homes and light commercial buildings are self-contained toilets that passively generate a modest vacuum to supplement the gravity flush. Fluidmaster, Inc. developed this vacuum-assist technology and currently licenses it to two toilet manufacturers: Briggs and Crane. The Briggs Vacuity® toilet, utilizing the WhisperVAC® Flushing System, was introduced in 1995 as the first vacuum-assist toilet. Crane Plumbing introduced its Vacuum Induced Power-Flush (VIP Flush) in 2000.

While totally passive, the functioning of vacuum-assist toilets is quite complex. Inside the porcelain tank are two airtight plastic vessels: the flush-water tank and a vacuum tank, which is connected by a tube to an air-filled portion of the swan-neck trapway. When the toilet is flushed, the air vent in the trapway becomes sealed by the draining water. At the same time, water draining from the vacuum tank creates a vacuum that is transmitted to the airspace in the trapway. 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 Briggs Vacuity and Crane VIP Flush both use 1.6 gpf, and both rate highly in independent tests. A primary selling feature, compared with power-assist toilets, is quieter operation. Cost is moderate: $200–$300.

True vacuum toilets

The other type of vacuum toilet is very different and—for certain applications—offers far more significant water conservation opportunities. With this technology—from Evac Environmental Solutions—a centrally located waste-collection tank 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. At the same time, the toilet bowl is rinsed and refilled.

Evac toilets use 0.4 gallons (1.8 l) per flush—75% less water than 1.6 gpf toilets. The technology was developed for ships and airliners, but Evac systems are now used in prisons and some other commercial buildings. Evac toilet systems are most common in stainless steel (owing to the correctional facility use), but they are also available in ceramic. The difference between this and the vacuum toilet systems used on airliners is that in this system water sits in the toilet bowl, and significantly more water is used during the flush; airplane toilets typically use only a half-cup ( &SUPER>1&/SUPER>⁄ ₃₂ gal or 0.12 l) of water—or whatever that blue liquid is—plus a lot of air. While the vacuum tank assembly is quite expensive (about $25,000 for a system to operate 150 toilets), Jim Womble of Evac told EBN that with several hundred toilets, their system can beat the first cost of conventional flushometer-valve toilets. And the significantly lower water use can make the life-cycle costs very attractive, the company claims. Pumps operate on demand and typically use a few hundred dollars in electricity annually, according to Womble.

Pump-assist toilets

Plumbing giant Kohler offers one toilet line, Power Lite™, that is powered by a pump. The small, submersible pump is housed in the low tank behind the bowl, and it forces water from the tank into the bowl during the flush. Kohler claims to achieve a flush performance similar to that of pressure-assist toilets—but at a significant cost ($700–$1,100). Unlike most toilets, the Power Lite models must be plugged in to operate. These models also offer users the choice of two flush volumes: 1.6 or 1.1 gallons (6 or 4.2 liters)—see “Dual-flush toilets,” below.

Air-pressure toilets

The California company Microphor offers a unique toilet that uses just a half-gallon (1.9 l) per flush, augmented by compressed air. Originally developed for boats, buses, and other applications where water was at a premium, Microphor began marketing their micro-flush toilets for residential and commercial applications about 20 years ago—focusing on areas with extreme water-supply or sewage-treatment problems. The company has a reengineered toilet for commercial/residential applications coming out by mid-2004 that uses just 1 quart (1 liter) of water. An air compressor, located in a basement, garage, or utility room, typically provides the 60 psi (410 kPa) air. A single compressor can serve a number of Microphor toilets. Cost of these toilets is high: $600–$900 plus the cost of a compressor.

Dual-flush toilets

An increasing number of toilets are becoming available that rely on an approach very popular in Europe and Australia: providing two flush volumes. In Great Britain, 75–80% of new toilets sold are now dual-flush, according to a June 2003 report put out by the Environment Agency. The handful of dual-flush toilets sold in North America deliver 1.6 gallons with the high-volume flush, which is used for solid wastes, and 0.8 to 1.1 gallons (3 to 4.2 l) with the low-volume flush, which is used for liquid wastes (and paper).

WDI-EcoFlush
Most dual-flush toilets operate with a fairly conventional gravity-flush technology, though the Kohler Power Lite models are powered by a pump, and the forthcoming Mansfield EcoQuantum has a pressure-assist flush mechanism from WDI, pictured above (see earlier “Pressure-assist flushometer-tank toilets” discussion).

How users select the flush-volume with dual-flush toilets varies widely by manufacturer. The Australian Caroma dual-flush toilets (the first dual-flush toilets introduced in North America) have separate flush buttons on top of the tank, one with a solid circle and the other with a half-filled circle. The Sfera S3 from HCG has a unique split flush handle. The Mansfield EcoQuantum has a handle that you lift up for a full-volume flush, or push down for a low-volume flush. (This configuration can be reversed if the user prefers.) The Controllable Flush, a dual-flush retrofit device for conventional high-flush toilets from the Athena Company in Aloha, Oregon, also has a handle that is either lifted up or pushed down.

Composting Toilets

While dramatic improvements have been made in water-conserving flush toilets in recent years, most flush toilets still use potable water—and a lot of it. A 1.6 gpf toilet flushed an average of five times per day (a typical per-person rate) will flush nearly 3,000 gallons (11,400 l) of water down the drain annually—over 7,500 gallons (28,400 l) per year for a typical household. Much better, according to many green building advocates, is to stop using potable water altogether and, instead of flushing wastes away, capture and convert them into valuable soil amendments. Composting toilets are the means to do that.

While composting toilets are beyond the scope of this article (see EBN &EBN volume="3" number="2">Vol. 3, No. 2&/EBN>), they should be considered in any low-rise green building project where water conservation is a high priority. While primarily used in homes, they are increasingly used in parks and nature centers, and a number of applications in commercial and institutional buildings have been well publicized and quite successful. Composting toilets are available in North America from about a dozen manufacturers and can also be custom-built on-site.

Retrofitting Older Toilets

There are hundreds of millions of toilets in the U.S., a majority of which use 3.5 gallons (13 l) per flush or more—some as much as 8 gallons (30 l). While replacing these with new toilets that use 1.6 gpf or less is the preferred strategy, that is not always possible for budgetary or design reasons. All older, high-volume toilets remaining in service should be modified to reduce water consumption.

Common toilet retrofit devices for water conservation are described in Table 1.

Table 1. Toilet retrofit devices

All but one of these reduce the flush volume. Some older toilets will not flush as effectively with less water, though the moderate reductions achieved with these products usually do not sacrifice performance significantly. In no cases will retrofitting an older 3.5 gpf (or higher) toilet bring the consumption down as low as 1.6 gpf.

Savings from Toilet Replacement

Water savings from replacing older toilets with new, water-conserving models can be dramatic. The tables below show projected savings in an average home and a 50-person office building.

Table 2.
Household Water Savings from Toilet Replacementt
Source: Data from Handbook of Water use and Conservation by Amy Vickers Table 3. Water Savings from Toilet Replacement in a 50-Person Office
Source: Data from Handbook of Water use and Conservation by Amy Vickers Actual savings from water conservation retrofit programs that have been implemented over the past 15 years show considerable variability. A very large program in New York City, in which 1.3 million toilets were replaced with 1.6 gpf models between 1994 and 1997, resulted in savings of 53.8 gallons (204 liters) per day per toilet, or a total of roughly 70 million gallons (260 million liters) per day. A Los Angeles program begun in 1990, in which 900,000 1.6 gpf toilets were installed, has reduced water use by 31.7 gallons (120 liters) per day per toilet, or a total of 28.7 million gallons (109 million liters) per day. A program in Tampa, Florida from 1993 to 1999, in which 15,300 1.6 gpf toilets were installed, saved 29.1 gallons (110 liters) per toilet per day, or a total of 440,000 gallons (1.67 million liters) per day. The greater savings found in New York City are likely due to the replacement of older toilets in that city, according to Vickers in the Handbook of Water Use and Conservation.

While saving water is the primary benefit of toilet replacement, energy consumption can also be reduced. For the 20% of homeowners not on municipal water systems, a small amount of energy for well-water pumping will be reduced. Assuming water is pumped from an average depth of 250 feet (76 m), the electricity savings from reduced water use amounts to approximately 3 kWh per 1,000 gallons saved (0.8 kWh per 1,000 liters), according to some quick back-of-the-envelope calculations by Paul Torcellini, P.E., of the National Renewable Energy Laboratory. Thus, replacing 5 gpf toilets in a typical home with 1.6 gpf models could be expected to save about 50 kWh per year (from Table 2).

For buildings served by municipal water and sewer, water conservation saves a considerable amount of energy—some from avoided pumping and generally more from avoided sewage treatment. In this case, savings do not accrue directly to the building owners, however. Nationwide, wastewater treatment accounts for about 75 billion kWh annually—about 3% of total U.S. electricity consumption. While the energy intensity varies widely, it is typically in the range of 1–5 kWh per thousand gallons treated (0.3–1.3 kWh/1,000 liters).

Finally Getting a Handle on Toilet Performance

It’s no great secret that not all 1.6 gpf toilets perform satisfactorily. While there has been dramatic improvement in 1.6 gpf toilets since the federal water conservation standards went into effect in 1994, lots of poorly performing toilets are still being sold.

All toilets sold in the U.S. must meet specific performance standards established by the American Society of Mechanical Engineers (ASME) and the American National Standards Institute (ANSI). Specifically, toilets must pass ASME/ANSI 112.19.6, “Hydraulic Requirements for Water Closets and Urinals.” To pass, a toilet must, in separate flush tests: leave no more than 25 out of 100 small polypropylene balls; leave no more than 125 out of 2,500 polyethylene granules; leave no more than two inches (50 mm) of a water-soluble ink line drawn one inch (25 mm) below the rim; and successfully dilute a blue dye solution from 1:40 to 1:100. Canada’s B-45 standard is a little tougher but voluntary.

By most accounts, the ASME/ANSI standard for toilet performance is not very rigorous—nor does it closely match real-world conditions. “We have a standard that means nothing,” says Gunnar Baldwin, a senior national account manager with Toto. Baldwin, who used to serve on the ANSI committee, told EBN that “every time the standards committee meets, it ends up watering down the standard until everybody’s worst product can meet it.” Virtually all toilets put through the ASME/ANSI tests pass without problem, yet many of those toilets cause problems in the field. As a result, there have been a number of efforts in recent years to more accurately replicate real-world experience.

One of the more widely reported independent studies was conducted by the NAHB Research Center in 2002 with funding from Seattle Public Utilities and the East Bay Municipal Utility District (see EBN &EBN volume="12" number="4">Vol. 12, No. 4&/EBN>). Forty-nine popular toilet models from 17 manufacturers were put through a battery of laboratory tests involving use of sinking and floating sponges and wads of paper at five levels of loading. Thirty-five of the 49 toilets were deemed to perform satisfactorily. The report generated a lot of controversy, with manufacturers whose toilets did well touting the tests, and companies whose toilets did poorly claiming the tests were flawed. The report was subsequently removed from the NAHB Research Center Web site, though it is still posted at www.savingwater.org.

At about the same time, Consumer Reports published an article on toilet performance (October 2002) and came up with strikingly different results. While nine of the top ten models in the NAHB-RC study were gravity-flush, for example, eight of the top ten models identified by Consumer Reports were pressure-assist or vacuum-assist. The Toto Ultramax, which tied for best performance in the NAHB-RC study, ranked only 20th out of the 28 models Consumer Reports studied.

One of the problems is that these tests don’t address the likelihood of blockages. “None of the tests represents a clogging test,” says Baldwin. “The most frequent complaint about the new toilets is that they tend to clog up easily and need to be double-flushed, plunged, or even snaked.”

Inspired by these problems with existing testing protocols, inconsistency among test results, and continued poor performance of some toilets, more than a dozen municipalities and utility companies in Canada and the U.S. funded a far more exhaustive investigation to follow up the NAHB-RC study: “Maximum Performance Testing of Popular Toilet Models” (MaP Testing).

Toilet testing at Veritec Consulting in Toronto, Canada. This Maximum Performance (MaP) Testing provides more meaningful assessment of toilet performance than the standard tests used in North America. Results, page 15. Photo: Veritec Consulting Initial results of this study, which was conducted by Veritec Consulting, Inc. in Mississauga, Ontario with advisory support from Koeller and Company in Yorba Linda, California (not to be confused with toilet manufacturer Kohler), were presented at the 2003 AWWA conference in June, and the final results should be available on the California Urban Water Conservation Council Web site by the time this issue of EBNreaches your desk (or shortly thereafter).

What makes the MaP Testing so unique was an attempt to come up with test media that behaves like human waste. The researchers, led by William Gauley, P. Eng. of Veritec, determined that the sponges, plastic balls, granules, paper balls, dye, and ink used in most tests just don’t act like the waste that real toilets are supposed to deal with. They turned to the medical literature to learn all about human stools, and they then set out to find a material that would simulate stools in a laboratory setting. Without going into all the fascinating detail, the average maximum stool size of an adult male is 250 grams, and the researchers picked that weight as the benchmark for acceptable toilet performance.

For the media, they developed a recipe for fermented soybean paste that could be extruded through a &SUPER>7&/SUPER>⁄ ₈” (22 mm) die. (The Japanese use a similar material for toilet testing standards.) “We’re pretty happy that it’s realistic,” said Gauley of the test media, which he described as “like gritty, grainy peanut butter.”

This test media, produced in 4” (100 mm) lengths weighing 50 grams (±5 g) each, was added to toilets in 50-gram increments, along with four loosely crumpled balls of single-ply toilet paper (six sheets each) meeting very specific ASME toilet paper standards. After each loading, the toilet was flushed. The solids loading and flush tests continued until the toilet failed to successfully flush 100% of the media in two out of three tests. In this way, they arrived at a maximum loading level for each toilet.

Before testing, each toilet was adjusted to flush exactly 1.6 gallons. (The NAHB-RC testing had found that many 1.6 gpf toilets actually flush with considerably more water.) The test protocol called for two toilets of each model to be tested, but that was not always possible. A total of 55 toilet models were tested initially and reported on at the AWWA conference; 90 are included in the final report, though several are retests of slightly modified toilet models or represent the testing of only a single toilet.

The findings are remarkable. Some 1.6 gpf toilets were unable to successfully flush 100 grams of media, while others successfully flushed over 900 grams! Of the 44 toilets purchased by the researchers and fully tested according to the protocol, 20 failed to successfully meet the 250-gram benchmark. At the other extreme, two toilet models that use the new Sloan Flushmate IV (1.0 gpf) successfully flushed 500 and 650 grams, respectively!

The researchers have been willing to retest toilets when manufacturers have gone back and tweaked the designs, according to Gauley. Niagara, for example, modified their Flapperless model (which tested at 200 grams) and raised the performance of this new prototype to 300 grams. Western Pottery raised the performance of their Aris toilet from 100 to 300 grams.

Gauley understands why some toilets have performed poorly to date. “Until now, they only had minimum criteria; that’s all they thought of testing to,” he told EBN. Manufacturers designed toilets that would satisfactorily flush the ASME/ANSI test media but generally didn’t go much further. (Toto has consistently done better with field performance because the Japanese have very different testing standards for toilets, using a soybean paste similar to that developed for the MaP Testing.)

Given the bad news for some of the manufacturers, Gauley is generally pleased with the industry reaction to the MaP Testing. “Surprisingly, the manufacturers are supportive of the testing protocol,” he told EBN. Veritec videotaped all of the testing, expecting manufacturers to challenge the results, but that hasn’t been the case. Manufacturers have followed up extensively, purchasing the test media so that they can do testing on their own in redesigning their toilets, or hiring Veritec to do the testing (US$800 per test). This is a lot more expensive than reusing sponges, but Gauley argues that the tests are worth it: “We’re getting toilets almost every day to be retested.”

There is a good chance that this new testing protocol will gain significant traction as it begins to be referenced by water conservation programs, including those of the sponsoring utilities and municipalities—which now number 19. (We will soon begin referencing the MaP Testing for listing toilets in GreenSpec, for example.) “We’re trying to come up with something that sponsors would buy into as a single set of requirements,” Gauley said. “We’re trying to bring some uniformity.”

Measured Toilet Performance

Results are given in grams of the test media successfully flushed.

* indicates toilets that failed to flush 250 grams—average maximum adult male stool size.

Gravity Models

Toto Drake 900
Toto Ultramax 700
Caroma Tasman (dual flush) 550
Glacier Bay Westminster 550
Toto CST703 550
Kohler Santa Rosa 500
Toto Ultimate RF 400
American Standard Colony 375
Foremost Premier 375
Foremost Regent 350
American Standard Sonoma 325
Toto Ultimate Elong 325
Vortens GTA 300
Mansfield Alto 275
Kohler Wellworth RF 250
*American Standard Plebe 225
*Sanitarios Azteca Sahara 225
*Niagara Flapperless 200
*American Standard Ravenna 200
*St. Thomas Marathon 200
*Glacier Bay Aragon IV 175
*American Standard Cadet RF 150
*American Standard Hamilton 150
*Briggs Abingdon III 150
*Briggs Altima III 150
*Crane Cranada 150
*Crane Cranada II 150
*Eljer Patriot 150
*Gerber Aquasaver 150
*Niagara Turbo 150
*Orion Iris RF 150
*American Standard Cadet EL 125
*Kohler Wellworth EL 125
*Western Pottery Aris 100
*Komet Deco 75

Pressure-Assist Models

Gerber Ultra Flush PA 900
American Standard Cadet PA 750
Crane Economizer 750
Eljer Aquasaver PA 550
Mansfield Quantum 450
St. Thomas Mariner II RF (1.0 gal) 275
St. Thomas Mariner II EL (1.0 gal) 250
Vacuum-Assist Models
Crane VIP Flush 725
&/TEXT>Briggs Vacuity 375

Preliminary results from the MaP Testing conducted by Veritec Consulting. Shown here are results from toilets that underwent full testing; other models tested less thoroughly are included in the final report.

Final Thoughts

This is an exciting time for the toilet industry (well, as exciting as toilets can get). Not only are new products coming onto the market all the time, but we now—finally—have reliable testing procedures in place that will be able to accurately simulate performance in the field. When we were designing toilets to flush plastic balls and sponges, we got toilets that did a very good job of flushing plastic balls and sponges. But what we need are toilets that do a very good job of flushing human waste, and that’s what we will get as the MaP Testing gains widespread recognition.

Additional data from MaP Testing—most of these toilets are not in the general list either because they were supplied by the maker or only one unit (rather than two) was tested.Table 4.
Toilets Using Less than 1.6 Gallons (6 Liters)

Green buildings need to be water-conserving buildings. State-of-the-art toilets using just a gallon (4 liters) of water per flush can help us achieve dramatic reductions in water use in any building. Composting toilets and the use of captured rainwater or treated wastewater for toilet flushing can help us go even further.

Published with permission from Environmental Business News.