Unalaska is no longer using toxic gasses to purify its drinking water. In late May, the city switched from using chlorine gas to sodium hypochlorite to treat the island’s drinking water in order to reduce wear and tear on local plumbing.
Public Utilities Director Steve Tompkins said the new chemical is much safer and easier on the island’s pipes than chlorine gas.
Sodium hypochlorite is essentially a very low percentage bleach made by passing an electric current through salt water. It’s not as hard on Unalaska’s household plumbing as the “very toxic” chlorine gas is, Tompkins said. It's also easier to manage.
“We changed the way we process our water in an effort to make it less corrosive so that we can avoid having to enter into some kind of different protocol with the [Alaska Department of Environmental Conservation],” Tompkins said.
The chlorine gas was beginning to deteriorate copper plumbing in homes, he said, causing copper to build up in the drinking water. Unalaska’s copper levels are only slightly elevated, according to Tompkins. But if they continue to rise, the city will have to implement a new strategy with the state to bring them down.
While copper is an essential nutrient and helps the body create energy, when it’s consumed in high amounts over long periods of time, it can cause liver and kidney damage.
The city tested 20 homes and two had amounts that surpassed the maximum contaminant level goal of 1.3 parts per million. There are no known or anticipated adverse health effects at or below this level, according to the Environmental Protection Agency.
McKenzi Berry also works for the public utilities department. She said those 20 homes that were tested aren’t just randomly selected.
“They are the oldest service lines in our system,” Berry said. “So if you see this number, and you're worried that maybe you're drinking these things, it doesn't necessarily mean that your water in your home has these levels. They are the oldest systems that have been in the ground longer, that have been exposed to these conditions longer, that are having these high levels.”
The city tests the island’s water several times a month throughout the year. Those tests are put together to create a report that’s released annually. It’s meant to help locals understand what’s going on with their drinking water. It’s also required by federal law through Safe Drinking Water Act amendments.
The public utilities department treats the water for a number of things: viruses, bacteria, radioactive material, pesticides. And they test for several contaminants, including turbidity, chlorine, uranium, lead and copper.
Tompkins said Unalaska’s treatment process was outdated.
“I think we were amongst the last couple [communities] in the state of Alaska using chlorine gas to treat their water,” he said.
According to Tompkins, the new water treatment program should also create a little less work for the city because they won’t have to worry about things like risk management plans for the toxic gas.
Logistically, there won’t be any major changes in how the city treats the water. Much of what happens during the treatment process is very similar, he said.
“So instead of dosing it with gas, you're dosing it with a solution,” Tompkins said. “You're still using chlorine as your primary agent, it's just in a much safer way.”
The water’s taste shouldn’t change much either, he said.
One thing that could change, though, is the cost. So far, the new chemical has been about the same cost to the city as it was for the chlorine gas treatment, even though Tompkins said he had predicted an increase.
He said it was just cheaper to get the salt to Unalaska than they had estimated. In the long run, the cost of the new program should be within 20% of the former treatment.
Tompkins said the 2022 Consumer Confidence Report also included a violation of missing samples in May. That month’s samples weren’t completed until the beginning of June, due to a staffing issue.
