City officials in Hastings voted this week to begin permanently disinfecting the city’s water using chlorine, a decision made after E. coli was found in the public water supply in September.

The city, which has put liquid chlorine in the water since it was contaminated, will switch to gas chlorination long-term. Until recently, Hastings was one of just five Minnesota cities with more than 5,000 people that don’t chlorinate its water.

“We think that the … consequences that could come from another [contamination] event are pretty staggering,” said Nick Egger, Hastings’ public works director. “This is about managing that risk.”

Even so, some residents object to the change, worrying that the chemical will make the water taste and smell bad or damage people’s health.

“We don’t have any great options in front of us that would allow us to be chemical-free, which I know is the desire of some people,” said City Council Member Lori Braucks. “Doing nothing is not an option.”

Braucks said that she’s also heard from some residents that it’s better to be safe than sorry, though no one is known to have gotten sick from the bacteria.

E. coli is found in water contaminated with human or animal waste. It causes diarrhea, nausea, cramps and headaches, and is especially dangerous for babies, young children, the elderly and people with weak immune systems.

Hastings officials estimate the price of gas chlorination at $440,000, with additional annual costs of $44,000. The capital cost will come from the city’s trunk water fund, Egger said.

Hastings had never chlorinated its water because tests hadn’t found any contamination, Egger said. But he said the city is likely “on borrowed time” before it happens again.

The root of last fall’s contamination was never discovered despite a federally required assessment. However, common causes include bacteria leaching into the soil through a pipe leak, or a “backflow event” in which bacteria is suctioned back into the water supply when someone is blowing out their irrigation system, Egger said.

Karla Peterson, who supervises the Minnesota Department of Health’s community public water supply unit, said that 56 out of the state’s 700 public water systems don’t add chlorine.

Besides Hastings, the sizable cities that don’t chlorinate are Grand Rapids, North St. Paul, St. Paul Park and South St. Paul. St. Paul Park will begin chlorinating next year once its treatment plant is built.

The state recommends disinfecting water but doesn’t require it, Peterson said. Gas is the most popular way nationally to chlorinate water, she said, because it typically costs less, has a good safety record and can be precisely controlled, unlike liquid chlorination.

Peterson said cities must weigh the pros and cons of disinfection. One drawback is that chlorine can combine with organic matter in water to create disinfection byproducts — carcinogens that can cause health problems. Water systems must test for them regularly.

Hastings residents expressed mixed feelings about adding liquid chlorine last fall after the E. coli detection. Some said the water irritated their skin or smelled like a swimming pool.

Jerome McNamara said the water had “kind of a weird taste.” But since he began using a Brita filter, he doesn’t think much about it.

“If [chlorine] ultimately makes the city of Hastings safer, I’m all for it,” he said.

On the other hand, Jeannette Trapp said, the chlorinated water ruined her $10,000 aquarium, killing her coral.

“I think it’s horrible. Can’t even drink the water anymore,” Trapp said. “Now I have to take filtered water out of my fridge [to] give my animals water.”

Some of the resistance to chlorine came from the pride residents take in the city’s water and the feeling that an era is ending, Braucks said.

“I think people just kind of grieve — we had good water and now we don’t. Now we have that big city water,” she said.