There’s something in the water in Castle Rock. Chlorine. Castle Rock Water says it’s all part of routine maintenance and the water is completely safe to drink.

CBS Colorado reporter Olivia Young tested the tap water in a Castle Rock home using a store-bought strip. She found the chlorine was 3.0 ppm. The EPA requires at least 0.2 ppm of chlorine in tap water but no more than 4.0.

Young found the pH of the tap water was around 7.6. Castle Rock Water says they keep the pH of the water between 7.5 and 8.5.

“Something’s not right within our water,” said Apres Coffee owner and Castle Rock resident Madison Vonderach.

While Vonderach says she uses a water filter at home and hasn’t noticed a difference, she says her customers have complained of a chlorine taste in their tap water.

“I have had a frequent amount of people, I would say, close to five different families, actually communicate to me that they’ve been noticing some concerns within their family’s health,” Vonderach said.

One Castle Rock resident told CBS Colorado her tap water has been making her family nauseous and giving her dog diarrhea. Another said his shower smells “like a swimming pool,” and the water has been giving him a sore throat.

“One of them in particular actually shared with me at some point that their wife fell ill and their animal fell ill,” Vonderach said. “Headaches and the stomach bug.”

“The water is safe to drink, but we make this transition to clean up the pipes,” said Castle Rock Water Director Mark Marlowe.

Marlowe says there is chlorine in the water, and that’s a good thing.

“Chlorine has been used for over a century in drinking water to disinfect it and keep it safe,” said Marlowe. “Disinfecting drinking water has been one of the most important achievements of public health in the history of the world, really. So it’s a very important thing.”

Marlowe says water utilities are required by state and federal laws to have a low level of chlorine in their water as a disinfectant. In 2013, Castle Rock Water switched from using chlorine to chloramine as a disinfectant.

“It’s chlorine plus ammonia that creates chloramines, and that’s what we typically use,” said Marlowe.

But Marlowe says when a certain type of biofilm develops on the pipes, chlorine needs to be used, so they’re making a temporary switch back.

“Lots of utilities will make this transition from chloramines to chlorine just to do maintenance on the system and clean that up,” said Marlowe.

Castle Rock Water warned neighbors they may notice discolored water and changes in taste and smell starting Feb. 2. Those impacts are most noticeable in the early days or in water taps closer to treatment plants.

“Down here, I haven’t tasted anything,” said T.A. Ike, assistant general manager at Wide Awake Eatery in downtown Castle Rock.

“The bottom line is, water is safe to drink,” said Marlowe. “There’s no danger to public health.”

Castle Rock Water says chlorine at the current level should not cause digestive or other health issues, and that anyone experiencing health issues should consult a doctor. 

Castle Rock Water will switch back to chloramine in May.

This is the first time the utility has had to do maintenance like this. They anticipate having to do so again in the future, but it could be anywhere from four to 10-plus years before it is necessary.

“The bottom line is they should not notice anything really going forward, except maybe a slight smell of chlorine,” said Marlowe. “You get used to your water, and you’ll stop noticing it, quite frankly.”

If Castle Rock neighbors are testing the water at home and seeing chlorine levels above 4.0, or if they have other concerns, Marlowe says they should contact Castle Rock Water. They can come test the water and make sure everything is okay.

“Call us if you have any concerns, if you think that there’s something that you need someone to look at, have us come out and test the water. We’re very responsive. We’ll be out there right away,” said Marlowe. “We just encourage people to give us a call. We’re friendly here. We like to talk to our customers, and we’d be happy to go out and meet with them and help them understand what we’ve done and explain everything to them.”

Community members can visit CRgov.com/WaterQuality for additional details. Customers with questions can contact Castle Rock Water at 720-733-6000 or by email at Water@CRgov.com.

Other solutions neighbors can try are to buy a water filter. Most Brita-type filters can reduce the level of chlorine and improve taste. Marlowe says neighbors can also leave water out for 24 hours, and most of the chlorine will dissipate.