Every year, the East Bay Municipal Utility District tests its water for over 100 substances, then publishes a water quality report for its customers, which compares contaminants to their state and federal goals or legal limits.
The news for East Bay water drinkers is good: In this year’s report, EBMUD said that its water met or surpassed every public health requirement set by the state and the Environmental Protection Agency (EPA), with low concentrations of contaminants like lead, coliform bacteria and chromium, a chemical compound that is recognizable as the subject of the true-story film Erin Brockovich. The federal limit of chromium concentration is 100 parts per billion (ppb) and the California legal limit is 10 ppb, although the state has set its public health goal at only 0.02 ppb. EBMUD’s chromium-6 levels are among the lowest in the nation, at 0.05 ppb.
“We’re pretty fortunate that we have a very clean watershed in the foothills of the Sierra Mountains,” said Andrea Pook, a spokesperson for EBMUD. She said that the utility company tests water from the treatment plant, from the reservoir and from the distribution system every single day—that adds up to about 20,000 tests a year.
Although the water scored low on contaminants, Pook warned that some residents might notice a change in how their tap water tastes this fall due to a treatment facility change that is currently underway. Some 800,000 people in the East Bay, including Oakland, get their water from EBMUD’s Orinda facility. On September 1, EBMUD began to transition that facility offline for maintenance, and to install a new backup electrical system, which will allow for easier maintenance in the future.
The switch to local treatment facilities might cause a change in the taste of the water because of different reservations’ algae content, which comes from slight variations in temperature, nutrients and water chemistry. Pook said the algae is filtered out of the system, but that its safe-to-consume byproducts leave a lingering earthy taste. Chilling the water might help with flavor.
“We expect it to last six months. We appreciate our customer’s patience. I would put this in the realm of short term pain and long term gain,” said Pook. The priority, she said, is a dependable water supply. She continued, “We want to make sure that the quality is there, and we want to do our best to make sure that the taste is what people expect as well, but for operational reasons it can’t always be perfect.”
Dr. Joseph Cotruvo, former director of the Drinking Water Standards Division of the EPA, said that part of the reason our water quality is so high is because it is surface water as opposed to ground water, which is often pumped from wells. “Ground water often has natural contaminants that you might be concerned about,” Cotruvo said. “There are places where there is arsenic in the ground water, from the natural geology, and that is regulated countrywide.”
Ground water, he continued, is also more vulnerable to industrial byproducts or waste, as was the case in Hinkley, California, home of the Erin Brockovich case. PG&E was using chromium-6 for corrosion control in the water that cooled their electric power plants. That water was released, and percolated into the ground water.
While the East Bay’s water quality results demonstrate purity, not all regions fare as well.
A report published on September 20 by the Environmental Working Group (EWG), a nonprofit environmental research organization with an office in Oakland, distilled the EPA’s 2015 data to show that chromium-6 appeared in drinking water in all 50 states. The report states, “EWG’s analysis of the test data estimates that water supplies serving 218 million Americans—more than two-thirds of the population—contain more chromium-6 than the California scientists deemed safe.”
The highest national chromium-6 levels were in Cleveland County, Oklahoma, where the average level was 29.59 ppb. In California, Yolo County had the state’s highest levels of 13.62 ppb, and Merced County water had chromium-6 levels of 11.41 ppb.
The EWG publication states that, “ingestion of tiny amounts of chromium-6 can cause cancer in people,” and supports adhering to California’s non-binding public health goal of .02 ppb over the much higher state limit.
But the scientific community disagrees about the extent of the dangers of chromium-6, and the levels to which regulatory standards should be set.
Chromium exists in two forms: as a naturally occurring nutrient called chromium-3, and as chromium-6, a compound that is associated with industrial processes—as waste from oil refineries, electroplating industries, and as a corrosion inhibitor in industrial cooling systems.
According to Cotruvo, “Chrom-6 has almost always been assumed to be carcinogenic by occupational inhalation,” meaning that it has been proven to cause lung cancer after being inhaled in industrial environments. He says it can also heighten the risk of intestinal cancer, if a person consumes a large enough quantity.
Cotruvo believes that the EWG report presents a conservative interpretation of the toxicity of chromium-6, because its authors didn’t take into account the findings of recent scientific studies, and because their estimates of chromium-related cancer cases are based on the very upper bound risk assessment. He described a recent Canadian report published in July, 2015, that examined what happened to chromium-6 after it was ingested “in common drinking water doses” by a mouse, rat or human. The stomach can convert chromium-6 into the nutrient chromium-3 before it passes to the small intestine—but perhaps not all of it. While the rodents didn’t do a very good job of turning the chromium-6 into the harmless nutrient, he said, “For humans, virtually zero got through the stomach.” According to Cotruvo, risk of cancer should be based on the amount of chromium-6 that makes it all the way to the small intestine.
But Dr. David Andrews, EWG senior scientist and co-author of its recent report, said that he believes many of the studies used to bolster this perspective were funded by the industries that often discharge chromium-6 as a byproduct.
Andrews said, “We don’t think there’s compelling evidence to reverse or completely abandon the standard process for establishing the safe drinking water based on chromium-6 being mutagenic and the potential for it to cause disruptive DNA damage at extremely low concentrations.”
In Cotruvo’s opinion, the bigger national cause for water quality concern is a microbial contaminant called Legionella. Legionella is a bacterium that, when inhaled in aerosols like steam, causes a lung infection that is a severe form of pneumonia.
“That, as far as I’m concerned, is the most significant water-borne disease risk in the United States, and probably in all of the developed world. Anybody who has an indoor plumbing system has that kind of a risk situation,” Cotruvo said.
“There have been about 32 reported drinking water outbreaks in last two years. Of those 32, two-thirds of them are legionellosis,” he said.
Legionella bacteria form long after water has been through the any water district’s treatment process, often in heating or cooling systems of large buildings, or in standing water inside a building’s pipes.
In the East Bay, EBMUD uses a complex process to clean and distribute local tap water.
At EBMUD’s Sobrante Filter Plant, two solid beige buildings are separated by two gushing water fountains, which turn out to not be fountains at all. They’re the first step in the water treatment process, the aeration of raw water, which helps oxidize metals to separate them from the water. That water is pumped into a rapid and slow mixing sequence that the plant’s water treatment supervisor, Bryan Miller, likens to a mixing a cake. Chemicals are added to disinfect, and to weigh down contaminants into heavier substances. A series of paddles whip those ingredients into the sedimentation stage that allows those heavier particles to quickly settle and separate from the purer water, made even purer by a solid filtration system that follows.
As water flows through these processes, its hue and clarity changes, from clear to a muddy brown to a dark green, to a clear turquoise. Just before it’s pumped out of the plant, chlorine is added to disinfect microbes, and ammonia to convert that chlorine into chloramine, which, according to the EPA, is more stable and longer lasting than chlorine.
Rick Sakaji, the manager of water quality at EBMUD, said that those disinfectants added after the filtration process are designed to target Legionella down the distribution channels. He said that EBMUD distribution pipes are also tested regularly for contaminants. But, he added, “once the water leaves our distribution system and goes into a high-rise or college campus, it’s no longer under our control.”
“From the standpoint of the public health goal, we’re very fortunate here at the district to have a very high quality source water,” Sakaji said of East Bay’s water. “We do everything we can to meet those standards—or be a lot better than those standards—in terms of the water we produce.”
Andrews credits EBMUD for how well they are reaching public health goals for preventing contamination from compounds like chromium-6. “The levels at .05 are very close to [the] public health goal. Out of 200 million that is very much on low end of the distribution we see across the country,” he said.
And Contruvo said that overall, “water in the United States is probably safer than it’s ever been since we started putting water into pipes and distributing it.”
When it comes to controversial compounds like chromium-6, he said, EBMUD’s supply is well below any calculated risk level, and for the East Bay, “the bottom line is that there is no need for concern.”
Correction: In a previous version of this article, the name of EBMUD’s water treatment supervisor, Bryan Miller, was written incorrectly.