After a drought-related delay, the city of Stockton is about to fundamentally change the way it treats drinking water.

And you may need to take action.

The long-planned switch from chlorine to chloramines should happen by the end of this month, said Mel Lytle, head of Stockton’s Municipal Utilities Department. For now, only city of Stockton customers on the north side will receive this water, though officials eventually intend to expand to the south side as well. California Water Service Co. customers are not affected.

Chloramines are widely used in the U.S.; water providers in the East Bay and San Francisco already rely on them. So does the city of Tracy.

The state and federal governments say water treated with the chemical is safe. “I’ve showered in it every day,” Bruce Macler, a water toxicologist with the Environmental Protection Agency, told The Record in 2014.

But the city’s proposal two years ago did generate at least some level of concern, based on largely anecdotal reports that people in other communities suffered health impacts that they attributed to chloramines.

Lytle says he understands those concerns.

“I think everyone’s very careful about the quality of their drinking water,” he said last week. “You’d expect them to be. But that’s what we’re trying to do, is make sure the water provided to Stockton is the utmost quality.”

What's the need?

The switch, in fact, is supposed to fix a recurring problem with Stockton’s water.

Twice in the past three years — including just last fall — the city has violated federal standards for potentially dangerous byproducts that form when chlorine mixes with organic material in water drawn from the Delta.

The violations aren’t an immediate threat — the health risk is based on many years of exposure — but city officials want to solve the problem.

They could have installed large filters to help treat the water, but those filters would have increased the cost of the city’s already expensive Delta drinking-water plant by about $15 million.

Instead, for roughly $4 million, officials decided to switch to chloramines, which are not as reactive as chlorine and are less likely to form those other harmful chemicals.

After making an announcement and notifying customers in 2014, city officials waited almost two years to actually make the switch.

They were worried about lower water levels in New Hogan Lake. So they took the unusual step of pumping water from the Delta as far as south Stockton. But wells in that area are not yet equipped for chloramines, so they decided to hold off on the transition.

With winter rains upon us, Lytle said the city is confident enough to move forward now.

“We’ve gotten sort of a better understanding of what potential drought impacts are,” he said.

Chemistry class

Chloramines are a mix of chlorine and ammonia. When low levels of chlorine are used, the combination is referred to as monochloramine.

If more chlorine is added, a more potent variety known as trichloramine can form.

You’ve probably been exposed to trichloramine in a heavily chlorinated swimming pool, as all of that chlorine mixes with sweat or urine from swimmers. The result can lead to skin irritation, red eyes or respiratory problems.

In the case of our drinking water, the mix of chlorine and ammonia will be at very low levels — as low as possible, Lytle said. The city has said the plan is to use on average about 2 milligrams of chloramines per liter of water, or the equivalent of two grains of salt in an entire cup.

You should know

Chloramines do change a few things for ordinary Stockton residents. Some things you should know:

• They are toxic to fish and other aquatic life. So is chlorine, but the difference is that chloramines don’t dissipate as quickly. If you aren’t already using conditioner for your aquarium or pond, make sure you start now. Most conditioners should work for both chlorine and chloramines, but check the label to make sure.

• They’re also toxic to mosquitofish, which are added to ponds to help control mosquito populations. “It’s something we’re going to need to look into further, but it could be potentially a problem,” said Aaron Devencenzi, a spokesman for the San Joaquin County Mosquito & Vector Control District.

• Water with chloramines must be filtered before being used for kidney dialysis. The city has notified local dialysis centers.

• Chloramines are more corrosive and may degrade rubber hoses and gaskets used for plumbing. Officials recommend asking for chloramine-resistant parts when tackling plumbing jobs. In some cases chloramines may cause lead from pipes to dissolve into the water, but the city says it can reduce the likelihood of that happening through regular water quality testing.

• Swimming pool owners may need to add more chlorine to their pools than they have in the past.

• If you’re concerned about perceived health impacts, you can buy a filter to remove chloramines. But they can be expensive.

‘A sign of the times’

Lynne Riggs of Stockton, who expressed concern about chloramines when news of the change was first made public two years ago, sounded resigned last week to the fact that it’s going to happen.

“They made that decision prior to any of the announcements we received in the mail,” she said. “They weren’t going to make any changes.”

She said that since some people appear to be sensitive to chloramines, she hopes experts will do more comprehensive studies about any potential risk.

At Randy’s Fish Palace on East March Lane, owner Randy Thomas said he posted copies of a city advisory so that customers know they need to be vigilant about protecting their fish. He said the owners of koi ponds should also be careful, especially if water is automatically added to those ponds to offset evaporation. Adding conditioner on a regular basis will be important.

“For the love of your fish, and for their well-being, do it from now on,” Thomas said.

He sees the addition of a new chemical to Stockton's water supply as a “necessary evil,” as water quality standards have tightened over the years.

“It’s just a sign of the times,” Thomas said, “and there’s no going back.”

— Contact reporter Alex Breitler at (209) 546-8295 or abreitler@recordnet.com. Follow him at recordnet.com/breitlerblog and on Twitter @alexbreitler.