WASHINGTON — Water and energy conservation can have some unintended consequences, a Virginia Tech professor told leaders of the plumbing industry at the Plumbing Industry Leadership Coalition meeting here in late April. Marc Edwards, informally known as the “plumbing professor,” has spoken before industry meetings before, which earned him the invitation to the PILC meeting.
The Plumbing Industry Leadership Coalition is co-convened by the leaders of Plumbing Manufacturers International, American Society of Plumbing Engineers and the International Association of Plumbing & Mechanical Officials. Its annual meetings include the top exec and top volunteer leader of every major group in the industry, such as Jerry Kennedy, executive director of the Plumbing-Heating-Cooling Contractors – National Association.
Professor Edwards, who did some early work on lead in drinking water, noted that for decades the industry has fought and won the war against contamination of drinking water caused by feces. Now legionella and other waterborne diseases are posing new challenges. Legionella accounts for 50% of the outbreaks of waterborne diseases and 93% of the deaths, he said.
Edwards covered five areas of his research: the performance of unleaded brass plumbing products, hexavalent chromium in water, water quality in LEED buildings, legionella, and changes in water chemistry.
First, the news on unleaded brass material performance is all good, he said. In looking at the new unleaded materials, they seem to be equal or better than the leaded components they are replacing.
The hexavalent chromium issue driven by publicity but little scientific information, Edwards said. Hexavalent chromium or chrome 6 is a carcinogen but maybe not in drinking water. (It is a carcinogen if welders breathe in the vapors.) Chrome 3 is often found in water because is a component of stainless steel; it is also a micronutrient. Currently EPA is considering regulating chrome6, and California has announced a Chrome 6 exposure goal of 0.02 PPB. The publicity has caused people to think they have a contaminant in their drinking water even though Chrome 6 is formed naturally in a lot of systems, including plumbing systems. In his research Edwards has found amounts in plumbing systems as large as 100 times the exposure level being considered by the EPA, with the Chrome 6 being released by stainless steel in the system. Edwards emphasized that research on Chrome 6 in water is very preliminary.
Water conservation measures in efficient buildings means that water stays in the pipes longer in generally warmer environments. Edwards cited water utility studies that show that conservation has resulted in water taking longer to get to buildings so it’s already old.
Edwards studied a LEED building at the University of North Carolina where nobody would drink the bad-tasting water. He discovered that water-efficient plumbing had cut water demand by 50%-60% and then rainwater recovery for toilet flushing cut fresh water use down by 90%. As a result, it took water two months to journey from the point of entry in the building to the bubbler in a drinking fountain. No wonder nobody wanted to drink it.
He’s found other efficient building with large volumes of water stored sometimes for months in cisterns. Even with UV lights and secondary disinfectant the water still contained high levels of legionella.
Legionella is still the major concern for water utilities, the plumbing industry and for building owners. ASHRAE Standard 188 defines responsibilities of building owners to deal with legionella.
“You can imagine every building having its own disinfection system,” Edwards said.
Legionella in drinking water may be the cause of the cause of 20%-40% of common ailments, Edwards said, like “a touch of flu,” although it does not cause illness from drinking it; it’s absorbed through mucous membranes. It also most commonly affects 35% of the population that’s at risk, including smokers, the obese and people over 65.
Use of granulated activated carbon filters to remove chlorine taste and odor causes problems because the chlorine is there to kill legionella.
High water temperatures will kill legionella but precipitates scale that clogs the pipes. Moreover, it’s impossible to get an entire plumbing system hot enough the kill germs.
Chemical disinfectants are also corrosive and will destroy materials. Chloramine, which has been widely used by water utilities for decades as a secondary disinfectant, disappears quickly, pretty much down to zero in six hours, Edwards said. Chlorine dioxide is another effective disinfectant but it is extremely corrosive and destroys PEX, HDPE and stainless steel.
“So you can imagine what will happen if building owners start dosing with this stuff,” he noted.
Copper-silver can discolor water and the copper can deposit itself on galvanized pipe and the silver will deposit on copper pipe.
These problems and their solutions often conflict with each other, Edwards said, on the issues of water conservation, energy conservation, scaling, scalding, corrosion control, water aging, and residual levels of disinfectant.
Research is needed so scientists and the plumbing industry can offer consumers good advice, but who will pay for it? Edwards fears that the issues will be addressed through litigation, the least effective way to handle it because any research coming out of lawsuits is highly biased and focuses only on the single issue at trial.
“I wish there was a silver bullet, but if it exists I don’t know what it is,” Edwards said.