Precious Water: Sustainable Indoor Water Systems

New techniques and technologies--including bathroom and lavatory fixtures--help boost full-building water efficiency
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Sponsored by TOTO and Zurn Engineered Water Solutions
C. C. Sullivan

The History of the Low-Flow Standard

The movement to reduce unnecessary water use, particularly in flush toilets, emerged in 1972 when Sweden passed its 6-liter code for toilets. Four years later the Swedish technology was introduced to the rural United States, in hopes of helping homes without access to a public water supply. Low-consumption (LC) toilets were already in use aboard trains and yachts as early as 1968. By 1978, a Penn State study showed that LC toilets were a simple solution to septic system failure; leading to the 1982 inclusion of low-flow toilets in ANSI standard 112.19.2, a voluntary national standard still on the books today.

In fact, the national water-conservation movement has been an outgrowth of problems with sewage treatment, more so than with drought. In Boston, for instance, strict water codes were passed in 1987 because of concern for the cleanliness of Boston Harbor.

The strategy was to reduce the burden on an overworked sewage treatment infrastructure, which would hopefully reduce the amount of polluted storm water runoff entering the waterways.

Amazingly, most U.S. toilet manufacturers failed to provide the technology, which was more frequently being adopted as required code. So in 1992, the Energy Policy Act (EPAct) actually required manufacturers to apply a 1.6-gpf standard to all new toilets. Many states and municipalities then provided additional momentum in the form of new codes and rebates. Since then, low-flow fixtures have generated debate on the true effectiveness of the water savings, as many users flush more than once.

The key for specifiers has been to focus on "paired performance," explains Sean Martin, VP Marketing and Sales with Zurn Commercial Brass and Fixtures Operations. "Design engineers have focused on the paired performance of water closets, urinals, and lavatories to deliver maximum top loading capability, anti-clogging fixture evacuation, line carry, and lower overall life cycle cost," explains Martin.

Another possibility, says TOTO's Baldwin, is that there may be fewer commercial-type toilets in public and commercial buildings, and instead more tank-type models, which can be quite effective. Issues of maintenance and vandalism will still influence choice, however. "The noisy blow-out bowls used in airports and bus stations are exempted from EPAct, but they are there to deal with human mischief, not to save water."

1992 Energy Policy Act: maximum flow rates

Fixture
Max. Flow Rate

Toilets

1.6 gpf
Urinals 1.0 gpf
Faucets 2.2 gpm (2.5 before 1998)
Faucets - commercial 0.25 gal/cycle, or .5 gpm
Metering Faucets 0.25 gal/cycle @ 80 psi
Showerheads 2.5 gpm
Spray Rinse Valves 1.6 gpm (as of 2005)
Source: U.S. Environmental Protection Agency

Realistic Tests for Low-Flow

As Jack expressed, concern over the effectiveness of low-flow toilets has contributed to their slow adoption. As seen in customer opinion surveys, the performance of LC toilets is required by the user to be virtually 100 percent effective, meaning that the user does not want to see any apparent residual waste after flushing. In recent years, the introduction of "realistic media testing" for low-flow toilets has provided design professionals, contractors and building managers with a more genuine appraisal of likely per-fixture water use by building occupants.

In the realistic media tests, solids are flushed to assess the performance of the toilet bowl and of the drain line carry. As early as 2000, ANSI conducted such testing concurrently with similar studies being undertaken in Canada, which were criticized for using such materials as sawdust, paper balls, sponges and dye, and the like, which did not adequately simulate clogging. Similar tests were performed again in 2003, resulting in similarly poor assessments of performance. Then, in Japan, tests employing both commercial and residential types of toilet paper were shown to much more accurately predict clogging issues; the inclusion of a soybean paste about the same consistency and density of human waste, improved the results significantly. These were "realistic" experiments because they combined both sinking and floating media (in this case, polystyrene balls).

Canadian testing groups borrowed aspects of the Japanese testing methods-even including an imported soy-paste medium-in 2002. Led by the consulting group Veritec, the Maximum Performance (MaP) Testing Program was launched, and it soon confirmed that "some certified and commercially available models do not meet customer expectation," said Bill Gauley who co-authored Veritec's study with John Koeller. Furthermore, MaP showed that low-flow toilets do work, when the prevailing opinion had been that low-flow toilets were ineffective.

The success of MaP testing in determining toilet performance, and of requirement programs such as the Los Angeles Supplementary Purchase Specification in demonstrating significant water conservation, eventually led to the development of UNAR, the Uniform North American Requirements. The UNAR specifications can be adopted by any municipality on a voluntary basis, and have been shown to contribute significantly to U.S. and Canadian conservation goals.

Still, LC toilet testing is not without its flaws, and the MaP test scores are often marketed heavily as proof of a robust fixture design. Architects, engineers and plumbing contractors should take care not to rely simply on a single rating number conspicuously advertised on a model that tested well. For instance, a model tested in 2004 may have a similar score to a model tested in 2005, but in 2005 MaP testing started encasing the solid media in latex sleeves. This had a dramatic effect on bowl water density, and thus on test results. For this reason some test scores cannot be compared directly.

 

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Originally published in GreenSource
Originally published in January 2008

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