Water Efficiency in the 21st Century: What are the concerns?

By Mary Ann Dickinson and John Koeller, Alliance for Water Efficiency

The Alliance for Water Efficiency, a non-profit organization headquartered in Chicago, has technical experts who have been working in the plumbing field for several decades. We offer our perspective here.

The past 20 years have resulted in significant gains in water efficiency. New plumbing products and technologies have produced massive water savings reductions in plumbing fixture flows. This change has occurred largely through the additions of water efficient devices and equipment to existing building plumbing systems. 

The passage of the Federal Energy Policy Act in 1992 originally set this in motion by establishing maximum flush volumes and flow rates for toilets, urinals, showerheads, and faucets. Flush volumes began to be further reduced, beginning in 2006, through the product labeling efforts of the U.S. Environmental Protection Agency’s (EPA) WaterSense Program. Green building programs and standards, such as the U.S. Green Building Council’s LEED program, ASHRAE standards, the Green Globes program, and various green plumbing codes, have also driven down water use in newly constructed buildings. 

The combined regulatory standards and specification programs have been highly successful, with the result that water consumption has dropped nationwide -- sometimes at the rate of as much as 1 percent per year. Here is an interesting statistic for just one plumbing fixture: the passage of the requirement for a maximum toilet flush volume of 1.6 gallons per flush in 1992 resulted in a total cumulative national savings of 18.2 trillion gallons of water – enough water to supply the cities of Los Angeles, Chicago, and New York for a 20-year period (see the infographic). This is an astounding amount of water savings, and the water efficiency community and plumbing manufacturers are very proud of this significant achievement.

But, this success is not without some issues and consequences. We enacted these flow rate and flush volume standards (as well as green codes and the national WaterSense product labeling program) on a separate, piecemeal basis. Water efficiency practitioners and plumbing engineers looked at the individual plumbing fixtures and failed to look at the whole, to approach the building’s water efficiency as an integrated “system.” We have incentivized and installed water-efficient plumbing products, appliances, and other equipment at an individual end use level, rather than as part of an entire functioning plumbing network. Thus, we are not accurately assessing the possible cumulative effects of the flow reductions in our plumbing products, some of which threaten health and safety. 

An example of the issue is the growing concern over the increased residence time for water in on-premise plumbing systems -- or put another way, how long treated drinking water seems to be now sitting within building water supply lines. Reduced demand and higher efficiencies in plumbing systems are creating longer residence times for water within building piping. In fact, storage of water within the pipes for such a long period of time means that the chlorine disinfection originally coming from the water utility may no longer be sufficient to protect public health. Thus, legionella and other pathogen growth is occurring in some of these building plumbing lines and fixtures, and cases of user illness and death have been documented by the Center for Disease Control and other research institutions. 

Definitive conclusions on the necessary remedies to this problem have not yet been determined, but could include point-of-use disinfection, UV treatment, or programmed pulse flushing at dead-end fixtures (thus obviously negating some of the hard-won water efficiency gains). This is a very critical area demanding further study before contemplating additional flow reductions in building potable water supply lines of commercial buildings in particular. 

A second important concern that we have failed to assess is the impact of all of our efficiency achievements on the drain lines and wastewater systems within commercial buildings. This, too, is deserving of attention by plumbing engineers. We must examine, first, how new efficient devices, fixtures, and other equipment connect to building waste systems, study how the drain lines are constructed, and analyze the function (or lack of function) of the system itself. Anecdotal stories from facility managers in the field began to emerge in recent years describing drain line blockages occurring in some commercial buildings. These were immediately attributed to efficient toilet fixtures, although there certainly were other contributing factors. As a result, it was recognized industry-wide that we needed to study this problem. Thus was born the Plumbing Efficiency Research Coalition (PERC), a collaborative research partnership of plumbing and water efficiency organizations chartered to address the issues emerging from super-efficient products. The six PERC organizations are: Plumbing Manufacturers International; International Association of Plumbing and Mechanical Officials; International Code Council; American Society of Pluming Engineers; National Plumbing, Heating and Cooling Contractors; and the Alliance for Water Efficiency. 

The first priority area identified for study within PERC was this issue of potential drain line blockages in commercial buildings caused by greatly reduced wastewater flows. Even the WaterSense program was reluctant to label commercial flushometer toilets to a 1.28 gallon per flush specification until such an analysis was completed. PERC undertook this assignment in 2012, and their Phase 1 commercial building drain line study completed in 2013 is an important step in assessing this situation. PERC’s report is available at www.plumbingefficiencyresearchcoalition.org. That study concluded that commercial flush valve toilets could indeed function at 1.28 gallons per flush without causing significant drain line blockages, even in buildings without much additional water flow through drain lines other than rest room waste flows. A follow-up Phase 2 study began in September 2014, to further address even lower flush volumes and pipe sizes and to gather the information needed to implement possible changes to design practices and the building and plumbing codes.

The figure from the PERC Phase 1 report illustrates, very clearly, the dramatic changes in water consumption (and water delivered to the waste system) since the 1980s. With a 60 plus percent reduction in consumption, can we realistically expect building systems designed to the criteria of the 1940s and 1950s (using criteria such as Hunter’s Curve) to always function properly in the 21st Century? 

Now is the time to examine our plumbing systems as a whole and to consider changes to design practices as well as to the building and plumbing codes. Plumbing engineers can and should play a vital role in providing the data and real-time solutions to the water supply and wastewater issues facing us today. We continue to need your expertise and we encourage you to remain involved!

The Alliance for Water Efficiency is a stakeholder based non-profit organization based in Chicago and dedicated to the efficient and sustainable use of water in North America. The alliance’s website offers detailed information contained online, and information on how to become an active member of the organization. The issues addressed in this article are being discussed in Alliance for Water Efficiency committees, and membership offers the opportunity to participate in these conversations. Visit www.allianceforwaterefficiency.org.

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