Water conservation research and legislative news, Part I
By Ron George,CPD,
President, Ron George Design & Consulting Svcs.
Numerous plumbing and conservation groups are working to conserve water and energy. Researchers have tested many models of water closets for their ability to flush the bowl contents and transport them at least 40 feet down the drain, in accordance with the ASME A112.19.2-2008/CSA B45.1-08 Ceramic Plumbing Fixtures standard. Maximum performance testing was developed to assess which water closets performed satisfactorily in the late 1990s, and testing has been updated in recent years. Information on the maximum flushing performance testing results can be found at www.map-testing.com/info/designers.html.
Several water conservation-minded organizations have joined forces to make sure that water use reductions are made with an eye on the big picture. We seem to be in a water reduction limbo, with many water and energy efficiency programs simply focusing on points for water use reduction, with no regard as to drainage system solids transporting performance at lower flow rates. Research is needed to determine the minimum flow rate to effectively transport solids down the drain line for each pipe size and slope. For this reason, several years ago I added the slogan, “Save Water Wisely” to the bottom of my emails.
Many states have arbitrarily selected water use reduction numbers based on goals in the green or sustainability programs offering points for water use reductions: LEED offers points for various 10 percent water use reduction increments. Many politicians who want to be perceived as forward thinking and environmentally friendly have proposed legislation to further cut water consumption by various plumbing fixtures in the year 2014 in California and Texas. It is like the 1992 Energy Policy Act all over again: Politicians are mandating water reduction goals that were chosen without testing or research to show whether those flow rates are attainable or sustainable.
Plumbing Efficiency Research Coalition
The American Society of Plumbing Engineers (ASPE) has joined the Plumbing Efficiency Research Coalition (PERC), which now has six member organizations. The coalition was founded in 2009 to develop research projects that will support the development of water efficiency and sustainable plumbing products, systems and practices. The goal is for projects to be financed through government grants, foundations and private financing.
The representatives of each of PERC’s member organization are: Jim Kendzel, executive director/CEO of ASPE; Mary Ann Dickinson, Alliance for Water Efficiency (AWE); Pete De Marco, International Association of Plumbing and Mechanical Officials (IAPMO); Jay Peters, International Code Council (ICC); Gerry Kennedy, Plumbing-Heating-Cooling Contractors National Association (PHCC-NA) and Barbara Higgens, Plumbing Manufacturers International (PMI).
The coalition has identified drain line transport as its first research project; IAPMO’s Pete DeMarco serves as project coordinator for this inaugural research study and also chairs the technical committee assigned to the project. Each of the member associations of PERC has named a representative to the committee. With the parameters of the project defined, the organization is now seeking funding.
In January 2011, representatives of PERC signed a memorandum of Understanding (MOU) with the Australasian Review of Reduction of Flows on Plumbing and Drainage Systems committee for their program known as “AS Flow” at the offices of the U.S. Environmental Protection Agency. Steve Cummings, an Australian researcher, and his colleagues have pioneered many ultra low flow drain studies in Australia because of water use restrictions. The MOU details several areas of collaboration between the groups to ensure that research efforts are not duplicated and that information and results are shared. The AS Flow program is also investigating the impact of reduced water flow in sanitary drainage systems, resulting from reduced water use from low flow plumbing fixtures and fittings, appliances and commercial and institutional equipment.
These ultra low flow fixtures have created a condition that is being referred to as “dry drain syndrome.” I have always said that there needs to be enough water in the river to float the boats. This research will determine what the minimum flow volume for various fixtures needs to be in order to have proper drain line transport of solids.
Critical drain line transport study needs funding support
PERC received its first research funding donations from the National Resources Defense Council (NDRC) Action Fund and “AS Flow” in Australia. The donations were reported to be for $10,000 each and are greatly appreciated; however, there is a long way to go for funding before research can begin. Budget projections show the first drain line research project will cost approximately $170,000. The coalition still needs to raise about $150,000 in funding before research can begin. Due to the complexity associated with the number of variables in “real world” plumbing systems, PERC representatives believe that a multi–faceted design experiment is required to properly measure the impact of the toilet fixture toward drain line transport relative to other plumbing system variables, such as pitch and flush volume.
Reduced flush volumes from high efficiency plumbing fixtures reduce the drain line flows. What is in question is whether these reduced flows are likely to cause an increase in blockages in the drain lines. Much of the U.S. information on this subject is anecdotal, without foundation in fact. We have all heard the stories about the increase in drain line cleaning service calls shortly after the Energy Policy Act of 1992 established lower flow rates for plumbing fixtures beginning in 1994. International studies and some field failures reported recently in Australia have indicated that flush volumes consistent with high-efficiency toilets (HET) or ultra-low flush (ULF) toilets may result in systemic drain line transport-related failures in building drains or sewer lines in those countries.
PERC has proposed a study to scientifically evaluate drain line transport issues and to determine whether the use of higher volume discharges at intermittent intervals (one or two percent of flushes) could be an effective way to clear drain lines. Drain line carry is a critical issue that must be better understood, as concerns over reduced flows have discouraged some utilities from implementing commercial HET replacement programs.
Due to a lack of funding, work has yet to commence on this study a full two years after PERC identified drain line transport as its first priority project and a year after the Alliance for Water Efficiency's (AWE) Research Committee identified drain line carry as its highest research priority. The AWE is inviting participation by organizations or manufacturers to become funding partners and step up to help get this important project launched.
Proposal to investigate drain line transport in buildings
To better understand where we are and how we got here we need to go back to the enactment of the Energy Policy Act of 1992, which set maximum flow rates for most plumbing fixtures. All water closets (toilets) manufactured in the United States or imported into the United States were required to flush no more than a maximum average of 1.6 U.S. gallons. Since manufacturers needed time to design and manufacture newer low flow fixtures, the legislation allowed a two-year grace period for residential fixtures and a five-year grace period for commercial fixtures. The legislation for residential models became effective January 1, 1994, and it became effective for all commercial models on January 1, 1997. At that time, concern for drain line solids transport efficiency was voiced by many in the plumbing industry and many of those in various professional associations.
Soon after the deadline, there were many reports of poor performing 1.6 gallon per flush (gpf) water closet models. It was also discovered that many people were finding ways to boost the flush efficiency by modifying some of the water closet models on the market in response to significant consumer complaints about poor flush performance. Since then, water closet manufacturers have made great strides in improving flushing performance. Intermittent and anecdotal complaints of drain line carry transport problems were not thoroughly researched prior to the legislation, and manufacturers placed much of the blame on oversized, older or faulty sanitary drain lines.
Recently, the need to find additional efficiencies on water-consuming plumbing fixtures to meet additional LEED point requirements has resulted in the creation of voluntary specifications that eliminate another 20% from the flush discharge volume of water closets, bringing consumption down to a maximum average of 1.28 gpf. At some point the laws of physics apply: If a 1.6 gpf water closet moves the solids 42 feet down the drain line, and if 1.28 gpf moves the solids 28 feet down the drain line, at some point the solids won’t move at all. There must be a minimum hydraic depth of flow or a wave depth for the solids to surf on.
The States of California and Texas have passed legislation to require all toilets sold in those states to be 1.28 gpf high efficiency toilets (HETs) by the year 2014. There are other provisions in California that will significantly accelerate this transition, and it is anticipated that other areas of the country will soon enact similar requirements. Some water closet manufacturers are now voluntarily offering models that flush at 1.0 gpf. One manufacturer is actively marketing a model that flushes at 0.8 gpf. This activity has rightfully raised the debate of drain line solids transport efficiency. Many plumbing experts are concerned that we are at or approaching a “point of diminishing returns,” where a significant number of sanitary waste systems will be adversely affected or plugged by drain line stoppages caused by poor drain line transport or what has been referred to as “dry drain” problems. Dry drains are especially a problem in larger commercial systems that have long horizontal runs to the sewer.
I witnessed the drain line transport problems in a hospital project. When we renovated a basement area of a hospital old 3.5 gpf water closets were replaced with 1.6 gpf fixtures. After the renovation, the drains became clogged every few weeks, and when hospital maintenance personnel removed the cleanout in the basement corridor of this multi-million dollar Magnetic Resonance Imaging wing, raw sewage ran all over the basement floor of the hospital. The cleanup costs were very expensive. This situation repeated itself several times, until adjustments could be made in the flushing volume. Was saving a few gallons of water worth exposing people to raw sewage on a regular basis?
I say, “Save water safely.” We need to perform the research before setting lower flush volumes. For many years, drain line transport problems have been reported in Europe and Australia and studied by AS flow members, further raising awareness and concerns here in North America.
Looking forward, newer technologies, such as non-water consuming and high efficiency urinals (HEUs), lower flow rate faucets, showers and increasingly efficient water consuming appliances will further reduce the amount of water discharged into sanitary waste systems. Equally significant are greywater reuse systems that collect discharged water from lavatory basins, clothes washers, bathtubs and shower fixtures in a residence for reuse, usually for irrigation purposes. This is another emerging technology that significantly reduces wastewater in residential sanitary drainage systems.
On the commercial side, the emphasis upon water and energy use reduction has resulted in a proliferation of products in the medical and food service sectors that substantially reduce flows to the drain. Liquid ring vacuum pumps that used to use water for a vacuum seal are being replaced with newer, water-free technologies. In commercial kitchens, the pre-wash sink overhead spray has proven to be a large user of water. Newer low flow pre-rinse spray heads can conserve large amounts of water and energy. To date, an extensive research project of sufficient scope has yet to be conducted that would determine whether significant problems could arise regarding drain line transport in these “efficient buildings.”
Emerging Technologies with Potential to Minimize Drain Line Blockages
Based on the casual observations of previous drain line transport research efforts, it is known that intermittent injections of clear water surges of sufficient volumes can flush the drains and transport solids in the drain line great distances and, theoretically, clear a building drain out to the connection to the sewer. For commercial installations, flush-o-meter-valves that employ hands-free electronic activation can now be programmed to flush at pre-designated times and at user-selected volumes.
For example, consider a commercial office building with restrooms employing a bank of High Efficiency flush-o-meter-valve toilets that flush at 1.28 gallons per flush (4.8 Liters per flush). For example, at pre-determined intervals, the toilets furthest upstream (on the drain line) can be programmed to flush once or twice per day with a higher flush volume that clears the building drain of all solids and transports the solids to the sewer.
These new programmable features have the potential to offer a very low-cost solution for many commercial installations. As such, PERC is recommending that this potential solution be worked into the test plan.
PERC Laboratory Testing for Drain Line Transport Study
The focus of this effort will be to verify the feasibility of using programmable flush-o-meter valves or other sources of clear water to clear long drain lines of deposited solids and to measure the relative importance of other systemic variables. This work would best be conducted on an apparatus employing 4” diameter pipe set at both minimum slope of one percent and a slope of two percent. The study would involve investigating various flush volumes so as to intentionally deposit test media along the length of the test apparatus. The data from the resulting transport distances will allow for determining the relative importance of the test variables. At the end of each test run, a higher volume clear water discharge will be introduced into the drain line apparatus (simulating a discharge from a pre-programmed flushometer-valve) in order to observe the clearing potential of the clear water discharge.
A 300 foot long (~90 meters) test stand is recommended to conduct this test. This will allow for adequate distance to show resolution in drain line transport at the various test flush volumes. In addition, the long distance simulates worst case commercial building drain installations and will allow us to determine if the high volume clearing has potential to clear very long commercial building drains.
To minimize costs, PERC will seek to conduct this test program on a suitable existing test apparatus. PERC is currently in the process of executing a MoU with the AS-Flow committee in Australia. Once the MoU is executed, PERC plans to review this test proposal with the AS-Flow Committee to determine the most cost effective location to conduct this work.
Look for part II of Ron George’s column in the September issue of Plumbing Engineer.
Ron George is president of Plumb-Tech Design and Consulting Services LLC. He has served as chairman of the International Residential Plumbing & Mechanical Code Committee. Visit www.Plumb-TechLLC.com, email Ron@Plumb-TechLLC.com or phone 734/755-1908.