Every year, Californians get a report card from their water department telling them if something is wrong with their water.
These polished brochures typically begin by laying out all the great things water agencies are doing with ratepayer money. It would be easy to just throw them away.
But near the end is series of hard-to-decipher charts that show what sort of contaminants have been found in their drinking water.
These are things, like bacteria, that could make someone sick immediately and others, like disinfectant byproducts, that could give someone cancer over time.
In San Diego, there’s very little bacteria or carcinogens. Most large water agencies don’t have major water quality problems. A notable exception is Camp Pendleton, which has repeatedly found unacceptable levels of bacteria  in the water it supplies to Marines. More typical, though, is the city of San Diego’s water department, which hasn’t had a water quality violation in more than a decade .
But there’s a difference between water that meets federal standards and water that is free of impurities. The federal government typically sets legal limits for contaminants  and then a state agency polices those limits.
California has a second set of standards, though. These are ambitious but unenforceable “public health goals ” for how clean people’s drinking water should be in an ideal world.
Most water districts, including the city’s, regularly fail to meet at least some of those goals.
The state’s Office of Environmental Health Hazard Assessment establishes the goals. That office is tucked inside the larger California Environmental Protection Agency, known as CalEPA.
For cancer-causing contaminants, the office typically creates a “one‐in‐one million” standard. That means that no more than one person in a million would get cancer if they drank the contaminant at a certain level for their entire lives.
For example, since 2006, the federal government has said water cannot have more than 10 parts of arsenic per billion parts water. At that level, 2.5 people per thousand could develop cancer. Anything above that is illegal.
California’s public health goals are stricter, though they’re unenforceable. The state hopes water districts can produce water that has only one part arsenic per 250 billion parts water. But the goal is so ambitious that lab results can’t confidently say if the goal is being met or not, according to the state’s Division of Drinking Water. Because of that, water districts only have to report to the public if they found two or more parts arsenic per billion parts water — more than the goal, but less than the legal limit.
The city of San Diego from time to time has more than a few chemicals in its water that exceed these state goals. The most common seem to be Trihalomethanes, a subgroup of compounds known as disinfectant byproducts. They are produced when chlorine or other disinfectants are used to treat water to eliminate bacteria. The city says it has taken steps to reduce these chemicals appearing in water, but they still show up.
Totally eliminating some of the contaminants from water may be impossible or, if possible, incredibly expensive.
Every three years, water districts are supposed to provide a report on how they’re measuring up against the state’s voluntary goals. The city’s Public Utilities Department forgot to do one in 2016 and is planning to submit one belatedly to the state after Voice of San Diego asked about it.
In 2013, though, the city concluded that trying to meet every goal was impractical.
“In some cases, installing treatment to try and further reduce very low levels of one contaminant may have adverse effects on other aspects of water quality,” a city report said .
For example, the city could use reverse osmosis — the same technology used by the new desalination plant in Carlsbad — to treat water, but that could have unintended consequences. Treating water that way can reduce its hardness, which can make water corrosive, which can then cause copper and lead pipes to leach those toxic metals into water. (A recent analysis of the effect of the desalinated water on the region’s water pipes found this sort of leaching was not happening.)
Even if that wasn’t an issue, the city said, the costs would be hard for customers to bear. It estimated additional treatment expenses would cost customers $537 to $1,028 per year.
The Helix Water District in East County came up with a similar figure — $500 to $800 a year for customers.
“That’s really expensive,” Helix’s director of water quality, Brian Olney, said. Plus, he wondered, “Can you even get rid of some of these contaminants versus what is some of their long-term actual health concern?”
The Environmental Working Group, an activist organization based in Washington, D.C., has been trying to raise public awareness about trace contaminants in people’s water. Bill Walker, a spokesman for the group, said it’s a sad commentary that water districts can’t meet these goals.
The group’s online database of tap water contamination has caused some confusion for California customers, perhaps because it’s more understandable  than what most agencies disclose to the public, even though it’s basically the same information. In contrast to the Environmental Working Group’s database, water agency reports that are sent to households are filled with fine print and inscrutable acronyms.
In 2016, the Otay Water District put out a press release trying to explain that the district complied with federal standards for one carcinogen, chromium-6, even though it was not meeting the state’s goals. It came in response to another Environmental Working Group report titled, “Erin Brockovich Carcinogen in Tap Water of More Than 200 million Americans .”
The legal limit for the chemical is 10 parts per billion. The public health goal is .02 parts per billion. About three-fourths of the samples tested in Otay exceeded the goal, but not the legal limit.
“A Public Health Goal is not a boundary line between a ‘safe’ and ‘dangerous’ level of a chemical, and drinking water is frequently demonstrated as safe to drink even if it contains chemicals at levels exceeding their Public Health Goals. Learn more about Public Health Goals,” the district said .
Walker said his group isn’t trying to alarm people with its database, but it does want to make sure they’re informed.
“We believe that people are smart enough to understand and interpret this information and that government should not be in the business of smoothing over a situation that might indicate some level of concern for some people,” he said.
The group recommends that people who are concerned about something in their water should get an additional home filtration system.