Does your tap water smell like chlorine? There’s a reason why.

You might have noticed in the last week that your tap water smells a bit more like a swimming pool than you’d like. If you have, it’s not just you: DC Water has begun its annual cleaning of our water lines, which uses chlorine to refresh and flush the city’s water system. 

Changes to the taste or odor of your drinking water can be jarring — and might make you wonder: is it safe to drink? The 51st spoke with a DC Water representative to answer your questions about the process.

What happens during the annual cleaning?

The Washington Aqueduct collects and purifies untreated water before supplying a potable version to the city and some of our neighbors in Northern Virginia. The federally-run facility typically uses chloramine, a combination of chlorine and ammonia, to regularly disinfect our water as it moves through the system’s pipes. 

But for a month or so each year, the Washington Aqueduct works with DC Water to switch to chlorine. It's a stronger disinfectant than chloramine, and helps the city’s water lines get rid of bacteria and the growth of biofilms (a.k.a., microorganisms that love to stick onto wet surfaces).

“It just continues to keep those pipes clean and supports us having good water quality throughout the year,” said Sherri Lewis, a senior manager of communications at DC Water.

During the process, DC Water continues to monitor the water to ensure it meets normal quality standards, as determined by the Environmental Protection Agency (EPA). This year’s annual cleaning lasts from March 23 to May 4. (More of an audio/visual learner? DC Water’s 2018 music video, “Chlorinate Me One More Time,” might be the resource for you.)

Is this connected to the Potomac sewage spill?

Not at all, says Lewis. While the Washington Aqueduct collects and treats water from the Potomac River, drinking water wasn’t impacted after a sewer pipe broke and spilled hundreds of millions of gallons of sewage into the river. 

“The main [water] intakes are upstream of where the spill occurred, and the intakes that were downstream were not in use and have not been in use,” explained Lewis. She added that the District’s drinking water system and wastewater system are separate.

Should I be concerned about my water smelling or tasting like chlorine? 

Lewis says some residents may notice a slight change in the smell or taste of their water during the annual cleaning, but that it’s normal, safe, and temporary. For those who own household plants or pets, the chlorine switch shouldn’t harm them either, Lewis said.

That being said, there are certain populations or facilities who have to take precautions, but those groups have to do so with chloramine, too. That includes dialysis centers, medical offices, and people who own aquatic pets. So if you weren’t already regularly taking precautions with your tap water, it’s unlikely you’ll need to start doing so now, said Lewis. 

“If you do have some specific health concerns, it's always good to reach out to your health care provider,” she added.

If the taste bothers you, Lewis says letting cold water run from your faucet for a short period of time or filling a pitcher of water and letting it sit in your refrigerator can help reduce the odor and taste. We still have just over a month left in the annual cleaning, so if your tap water tastes a little different, sit tight (and maybe buy a water filter in the meantime).