Water Conservation: It's Not Easy Being Green

By Ron George, CIPE, CPD

President, Ron George Design & Consulting Services

The "WaterSense" program is one of the latest water conservation programs sponsored by the Environmental Protection Agency (EPA) with the support of many water conservation groups and individuals. WaterSense is a certification program. The WaterSense label identifies water saving products, practices or programs that are approved by the EPA.

Who could be against saving water? The answer is very few people, as long as they can take comfortable showers and flush their toilets without having them plug up. The key to the program's success will be to make sure that, in addition to water conservation, performance and user comfort issues are also considered in the evaluation criteria used to determine whether a product earns the WaterSense label. In other words, the WaterSense program must make sense.

Federal legislation passed as part of the Energy Policy Act of 1992 required showers that previously flowed as much as 7 gallons per minute (gpm) to be reduced to a maximum of 2.5 gpm. The reduction to 2.5 gpm showerheads saved water, it saved fuel to heat the water, it saved electricity to pump the water and, most importantly, it still allowed enough water to flow to provide an adequate shower.

The EPA is now considering lowering the shower flow rate in order for products to qualify for the WaterSense label. Water conservation programs are good and are needed for areas of the country experiencing drought conditions or significant population growth. My concern is that, if the only criteria these programs look at are reduced flow rates, we could be going back to the days of outhouses; the highest scoring plumbing fixture might be the waterless shower, followed closely by a damp sponge and showers that work something like the produce-misting systems.

Low flow showerheads will not get high scores for user satisfaction, and they raise many health and safety issues. The health issues include poor cleaning and rinsing at low flows and Legionellae exposure from the fine mist associated with ultra low flow (ULF) showers. One safety issue is that many shower mixing valves are incompatible with ULF showerheads and cannot control the temperature properly at low flows.

The Energy Policy Act of 1992 also brought us the 1.6 gallon per flush (gpf) water closets that performed poorly in the first several years after the requirements went into effect. That legislation mandated low flow water closets without any research on the subject. No one wants to repeat the follies of the 1.6 gpf issue. We ended up suffering with product that had design problems because of the short implementation time, drain line carry issues, fixture performance issues and poor user satisfaction.

I agree that we need to design water conservation systems now to reduce the water demands for future generations, but the WaterSense program has raised a few eyebrows. The manufacturers, engineers and others in the industry that I have talked with were concerned that the new program might be overlooking some serious issues and focusing only on water conservation. What good is a an extra percent or two of water conservation if it creates a dangerous system that can severely injure or kill someone from scald injuries or if it creates unsanitary conditions from inadequate flow in the shower or from sewage back-ups caused by blockages in drain lines related to inadequate drainline carry?

Water use statistics

According to a U.S. Global survey conducted in the 1990s by the EPA, indoor household fresh water use was about eight percent of the total water use. Outdoor household water use was about five percent of the total fresh water available and non-household uses accounted for 87 percent of the available fresh water. Of the eight percent used for indoor household use, about 30 percent was used for flushing toilets, about 30 percent for bathing or washing and about 40 percent for other uses, including drinking, dishwashing and clothes washing. Showers accounted for about two to three percent of overall water use.

We should step back a little, look at the big picture and consider the biggest users of freshwater: irrigation, commercial and industrial uses account for 87 percent. It seems that the opportunity for water conservation is much greater in these sectors than it is in household use. Also, aging infrastructure causes water main leaks, resulting in a significant, yet somewhat unaccountable, amount of water loss.

We should look at saving water wherever we can. The WaterSense program is an opportunity to "get it right" the first time and should address other considerations as well as water conservation. We must consider other important system design issues such as drain line carry for dual flush water closets, pressure disturbances in systems with low flow showerheads and older shower valves that can cause scalding or thermal shock situations.

ASME/ASSE harmonization efforts

I recently attended a joint harmonization task group meeting in Reno, Nevada, between ASSE 1016, dealing with shower valves and ASME A112.18.1 clause 5.10, dealing with showerheads. Sally Remedios of Delta Faucet Company is chairing the ASME effort, and she is doing a great job of trying to educate water conservation groups on the issues relevant to showerheads and shower control valves. A discussion was held on the test pressures used in the standard for the valves versus the test pressure used in the standard for the showerheads. Valves are tested at a pressure of 45 psi; showerheads at 80 psi. So which one needs to be adjusted? Probably, both need to be adjusted to the same pressure.

A showerhead should never experience 80 psi because of the pressure drop associated with flow. If there is 80 psi of static pressure in a plumbing system, when the water starts flowing there is likely to be a pressure drop through the building supply pipe, meter, backflow preventer, water heater, shower mixing valve and branch piping. The friction loss can be about 15 to 20 psi. So, if the pressure supplied to the shower valve inlet is 60 psi when the flow starts, it is more likely to drop to something like 40 psi when the water is flowing. The actual pressure would depend on the length of piping and fittings, but the valve should never see 80 psi.

There needs to be a way to match shower valve flow rates to showerhead flow rates. When a non-compensating showerhead is supplied with 45 psi, or any pressure lower than 80 psi, the flow will be less than what is published on the showerhead. Maybe a showerhead needs to have two flow numbers, one at 80 psi for the maximum flow possible and one at 45 psi so that it can be matched to the shower valve.

Many organizations were represented at the meeting, including the EPA, the California Energy Commission, industry consultants, manufacturers, testing labs and design professionals. Representatives of the EPA WaterSense program outlined the program and pointed out that it is a work in progress.

The task group discussed many issues, including the impact of low flow showerheads on shower valves. Shawn Martin, of the Plumbing Manufacturers Institute (PMI), presented temperature control test results from 15 shower valve manufacturers. The results showed that 100 percent of the valves passed the ASSE 1016 test at 2.5 gpm. When the shower valves were flowing 2 gpm, only 77 percent passed the test, and, when flowing 1.5 gpm, only 67 percent passed. When the flow was reduced to 1 gpm, only 34 percent passed the test. This test data indicated that lower flow showerheads are indeed a concern if they are installed with existing shower valves.

Just mandate them

One of the California consultants did not seem to care about any of the engineering concerns or user comfort issues that were discussed. He simply wanted to mandate lower flow fixtures. He said, "I don't care about user comfort; we'll just tell them what they can use, and they will have to use it."

Several manufacturers and others, including myself, spoke up after hearing his comments and said that we did not want to blindly choose a flow rate that does not provide user satisfaction. The consultant kept talking about the water savings from reduced shower flow rates, using his simple calculation of flow rate. His logic was that if existing showers flow 2.5 gpm and the new showers are 1 gpm, then during a 10-minute shower you should save 15 gallons of water. I pointed out that the water savings would not be 15 gallons, because with low flow showerheads people will generally take a longer shower. The overall savings could amount to just a few gallons. The cost of this savings in health, safety and user comfort and satisfaction can be high.

We continued to discuss the concerns about low flow showerheads causing flow restrictions and about the scalding and thermal shock that can occur with non-compensating and two-handled shower valves. These are serious liability issues for any water municipality that is considering simply handing out low flow showerheads in their water conservation efforts. They need to provide warnings, to make sure that the shower valve is not two-handled and that single-handled shower valves are ASSE 1016 compliant, with the maximum temperature limit stops adjusted to prevent scalding. The shower valves should also have check valves to prevent cross flow across the valve and to control temperature at the reduced flows.

Research funding needed

Everyone agreed that there is a great need for research to determine a minimally acceptable shower flow rate that will still provide user comfort and address several issues, including the following:

• temperature control
• water droplet or mist size (to prevent Legionellae in the water supply from being becoming aerosolized in the water mist)
• velocity of water spray
• scouring action
• shower temperature setting based on entrained air and evaporative cooling and wind chill effect
• additional time required to shower properly because of lower flow rates
• concerns about thermal shock or scalding with flow-restrictor type showerheads and older two-handled or non-compensating type shower valves.

WaterSense is currently in the process of writing letters to legislators asking for increased federal funding for the program. If the funding comes through, I hope that they will be able to research and address some of these issues.

WaterSmart

While I was in Reno, the American Water Works Association, Southern Nevada Water Authority and the EPA cosponsored a "WaterSmart" conference on water-efficient practices along with a water efficiency expo. There were a lot of great water and energy savings ideas at the expo; however, quite a few of the products had code violation and engineering design issues. Many products were developed by entrepreneurs who had great ideas, but who were apparently unaware of requirements in the plumbing codes and of general engineering principles for safe plumbing.

Many ULF showerhead manufacturers were touting their new water mist showerheads. Some had aerators and venturis that entrained air, and some had very high velocities, which create quite a wind chill effect in the shower and would cause the temperature setting of the shower valve to be set higher. The misting heads increase the possibility that Legionellae bacteria in the water droplets will be inhaled into the lungs.

Some manufacturers have teamed up with municipalities to distribute ultra low-flow showerheads to water utility customers. It turns out that the showerheads were simply handed out, with no regard as to the type of shower controls they would be used with. Distributing these showerheads without verifying that the shower valve they are used with is designed to control water temperatures at very low flows is extremely dangerous and is likely to lead to an increase in scalding and thermal shock incidents.

Two-handled shower valves have a mixing chamber or piping that allows cross flow between the hot water and the cold water system. For showerheads that have a high volume flow, the path of least resistance for the mixed water is out of the showerhead. If a high volume showerhead is replaced by a low flow showerhead with a flow restrictor, using an adjacent toilet or fixture can cause a pressure drop in the cold water line; the path of least resistance for the hot water is then through the mixing chamber and up the cold water supply pipe. This produces a burst of hot water that can scald someone.

There are numerous engineering solutions at varying degrees and costs, such as adding thermostatic mixing valves to temper the hot water to a safe temperature, replacing the two-handled shower valve with an ASSE 1016-approved shower valve with a temperature limit stop or providing an ASSE 1062 temperature-actuated flow reduction device to shut down the flow of water when it approaches 117 F.

The WaterSense program is still under development; many people are hoping that the program will consider user satisfaction and the health and safety issues, as well as water conservation. Another WaterSmart Innovations conference is scheduled for Oct. 8 -10, 2008, at the South Point Hotel & Casino in Las Vegas.

Ron George specializes in plumbing, piping, fire protection and hvac design. He also provides  plumbing/mechanical code and product standard consulting services and forensic investigations of mechanical system failures.