PHCC Helps Complete
High-Performance Toilet Study
In today’s movement toward high efficiency and water conservation, high-performance toilets are an important component in saving water. The push to lower-flush water consumption is not without risk, as consumers—and contractors—are concerned about stoppages in drainage systems.
Fixtures have been mandated at a maximum average flush rate of 1.6 gallons per flush (6.0 liters per flush) for many years. (And the change was quite controversial, as many of us remember.) Further reductions to 1.28 gallons per flush (4.8 liters per flush) have been adopted in some jurisdictions, and there are some fixtures available to flush as low as 0.8 gallons per flush (3.0 liters per flush). With all of these changes, it became apparent that some research would be needed to determine the effect of high-efficient toilets on plumbing systems, many of which are part of an aging infrastructure.
PHCC—National Association is part of an industry group, the Plumbing Efficiency Research Coalition (PERC), that is leading efforts to advance plumbing research initiatives pertaining to water efficiency. The coalition just completed Phase 1 of a long-anticipated study on “Drainline Transport of Solid Waste in Buildings.” The work plan had a scope considering a commercial-type application where a remote toilet room with a long horizontal drain, a worst-case scenario, would be subjected to a surge of water to act as a clearing flush. The complete study is available on line at ww.plumbingefficiencyresearchcoalition.org.
Through a generous contribution of material and lab space, the actual testing was conducted at American Standard Brands Product Development Design Center in Piscataway, N.J. The testing simulated real-life conditions in a commercial setting.
The test results indicated that a clearing flush would be an unreliable solution and that 0.8 gallon per flush toilets may cause problems in commercial applications that have long horizontal drains and little additional water sources to assist drain line carry.
Interestingly, a significant factor appears to be strength of toilet tissue. The stronger tissue had greater effect in the studies, indicating consideration of tissue type may provide some assistance in stoppage-prone applications.
Additional studies are being considered by PERC to build upon this information. Other products such as flushable wipes, seat covers, and other consumer flushable products could be considered. Investigating different pipe sizes, slopes, or materials could well provide insight into increasing our ability to offer high-performance devices in the future.
What the Drain Line Study Involved
As a first step, past research on various types of fixtures and drain configurations was reviewed and considered. Then, PERC developed a work plan to test the effect of a clearing flush, or a surge of water, done periodically to remove any accumulated waste buildup.
The first test consideration identified was waste transport in a commercial setting, visualized as a remote toilet room in a facility that would have a long horizontal run with no sources of additional drainage water to assist drain line carry.
An apparatus was constructed of four-inch clear PVC pipe that extended 135 feet in length. The device had two long-sweep 90-degree elbows, at about mid-length, which turned the flow 180 degrees back to the starting point.
The volume of the flush simulated the effects of 1.6, 1.28 and 0.8 gallons per flush. No actual fixtures were used to eliminate bias toward a particular manufacturer or type of toilet.
A surge injector was constructed for each flush volume to allow random loading of miso paste, which simulated solid waste and toilet tissue. Forty test runs of 100 cycles each were conducted using these devices. Several variables were presented and considered: volume of the flush, slope of the drain, flush rate of the device, percent of trailing water and the toilet paper type.
The last consideration was the wet tensile strength of the toilet tissue. Some evidence exists from an Australian study that the stronger the tissue, the greater the incidence of stoppages. A variety of tissues were tested, with the strongest and the weakest being selected. No intent was made to identify or recommend brands of tissue.
For more information, contact Chuck White, Vice President of Code and Technical Services, at email@example.com.