Published June 28th, 2017
Contaminants creep up but water still safe in Lafayette
By Pippa Fisher
Photo Pippa Fisher
Following a flurry of media reports and alarm on social media about increased contaminants in local water, should Lafayette residents be worried their drinking water might cause cancer?
East Bay Municipal Utility District says no. In correspondence with the city of Lafayette, EBMUD Community Affairs Representative Kathryn Horn says, "I want to clarify that EBMUD drinking water quality remains in full compliance with all state and federal regulations, and the district is confident we will remain in full compliance."
At issue are higher than usual levels of trihalomethanes (THMs)- disinfection byproducts formed when chlorine reacts with naturally-occurring organic matter in water - that have been found in Orinda and Berkeley at two testing locations where individual samples indicated THMs above 80 parts per billion (ppb).
EBMUD says that the system average is currently at 58ppb, exceeding its own internal goal of 40ppb but that it continues to be under the state and federal limit of 80ppb.
People with long-term exposure to drinking water containing THMs in excess of state and federal limits may be at increased risk of getting cancer.
A two-step process protects public heath. Filtration through sand, gravel and charcoal removes dissolved particles like dust, parasites, bacteria, viruses and chemicals. Then, chlorine or chloramine is added to disinfect and kill any remaining parasites, bacteria and viruses. Ironically the past wet winter, which allowed the district's cup to "runneth over" with abundant water, is partly to blame for the increased THMs as it washed larger amounts of organic materials into the source water, requiring more disinfection leading to more disinfection byproducts.
Additionally, over the past few drought years, residents have cut back significantly on their water use, causing water to sit longer in tanks and pipes, necessitating further disinfection.
Lafayette, Orinda and Walnut Creek receive their water from Pardee Reservoir - a pristine Mokelumne River source in the Sierra Foothills.
In fact because of the purity of the water source EBMUD Spokesperson Jenesse Miller said, "Our water treatment plants did not need the additional treatment steps and equipment required to address these elevated organics until recently.
"Improvements are planned (and included in our proposed two-year budget and rates) to provide these added systems at our water treatment plants to address these organics should this issue continue," she said.
EBMUD is currently addressing the challenge with increased water quality sampling, operational changes and a new flushing program. Additionally the district is testing THM removal technologies through a pilot aeration system at the Lafayette Water Treatment Plant.
Miller says that the district is currently flushing pipes in areas most affected. "Flushing removes sediment and mineral deposits and helps maintain a chlorine residual within the distribution system to ensure the delivery of high quality water to customers."
Miller explained that EBMUD is also considering accelerating plans that are already underway. "Our five-year capital improvement plans include reliability and improvement projects at several inline water treatment plants, which will reduce disinfection byproducts significantly."
Miller emphasized that no home filters are necessary and pointed out that at that moment she herself had a glass of water on her desk - unfiltered.

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