Why Does My Water Smell? - Consumer Reports

Why Does My Water Smell?

Here are the common culprits—and how to get rid of them

By Perry Santanachote January 19, 2020

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Nothing quenches thirst like a glass of crisp, cold water. And perhaps nothing is more gross than getting a mouthful of what smells like a swimming pool or rotten eggs instead.

If you find yourself holding your nose while drinking tap water, you’re not alone. A recent nationally representative Consumer Reports survey found nearly half of Americans who drink city water complained that their tap water at home had unpleasant tastes or odors.

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The good news is that common odors and flavors in tap water aren’t harmful to your health, according to Joel Baker, science director at the Center for Urban Waters at the University of Washington Tacoma.

Still, who wants to drink smelly water? “Fortunately, most water filter pitchers do a great job at removing these flavors and odors,” says Joan Muratore, CR’s lead tester for water filters.

Here’s a look at what exactly could be mucking up your tap water, plus details on how Consumer Reports tests water filters' ability to get rid of unwanted flavors and odors. We also highlight water filter pitchers that score well in our taste and odor tests. For more on water filters, see our water filter buying guide, and consult our water filter pitcher ratings to see how each model we test performs.

Want cleaner water from your sink’s tap? Find the best under-sink water filters from our tests.

What’s That Smell?

How your water smells and tastes has a lot to do with the quality of the water source, Baker points out. “Utilities focus on preventing the transmission of water-borne disease, which is by far their most important job," he explains. "They do their best to control taste and odor issues, but some smells can persist.”

Chlorine is one of the most common offenders of objectionable water, especially if the water source is a municipal water system (84 percent of Americans have municipal water, based on our 2019 Water Quality Survey). The chemical is used in water-treatment facilities to get rid of disease-causing bacteria, viruses, and parasites, and utilities are supposed to use just enough of it to get the job done. But "occasionally they overdo it, which can leave traces in the drinking water,” says Baker.

Other common causes of funky water come from naturally occurring compounds near the water source, such as algae or microorganisms. If your water smells like rotten eggs and vegetables or a sewage treatment plant, the offender is probably dimethyl disulfide, which occurs naturally in soil and is generally produced by microorganisms living in oxygen-poor environments. You can taste and smell it even at low concentrations.

A musty, earthy aroma can come from geosmin or 2-methylisoborneol, compounds released by certain species of algae in or near the water source (usually lakes and rivers). And again, even a tiny bit can cause water to smell. You may notice seasonal fluctuations in these odors, too. Late summer is the time when algae bloom and die, so the water may be particularly pungent then.

If you have well water and it looks cloudy or rust-colored and tastes metallic, that’s likely from ferrous sulfate, a water-soluble form of iron that can find its way into groundwater.

How CR Tests Water Filters for Flavor and Odor Removal

We work with professional taste testers at Sensory Spectrum, a sensory consulting firm in New Jersey, to assess how well each water filter we test neutralizes the tastes and odors mentioned above.

“Clean water should feel soft on the palate with no aroma or taste,” says Gail Vance Civille, president of Sensory Spectrum. “Since it mimics saliva, no other differentiating characteristics should be detected.”

For CR’s tests, Vance Civille’s team spikes pure spring water with droplets of the compounds that make water smell and taste like common contaminants in water: a swimming pool, rotten food, damp soil, and pennies. Then the water goes through a water filter.

A panel of eight to 12 tasters does a blind sniff and taste test of the filtered water against a baseline of pure spring water. For each water filter, they assess two batches with low levels of contamination and two batches with high levels of contamination. Tasters rate each sample on a scale of zero to 10—zero meaning the filtered water smells and tastes just like pure spring water, and 10 meaning the filtered water still smells and tastes full of contaminants.

Water Filter Pitchers That Clear the Stench

Pitcher-style water filters are an inexpensive way to turn tap water into great-tasting water. These three models from our tests score an Excellent or a Very Good rating for removing flavors and odors.

What’s in Your Water?

Do you have bad-tasting water? Consumer Reports experts Perry Santanachote and James Dickerson explain how to find out about water testing and the best filtration systems.

Perry Santanachote

As a multimedia content creator at Consumer Reports, Perry Santanachote covered a range of trends—from parasite cleanses to pickleball paddles. Perry was also a main producer of our Outside the Labs content, evaluating products in her tiny Manhattan apartment.

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