Taste and odor issues in drinking water

A kid wearing a red and white striped shirt is drinking cold, refreshing water from a glass.
Taste and odor changes in drinking water can be caused by a variety of factors, including your home plumbing. Learn more about taste and odor issues in drinking water and how to troubleshoot them.
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How to troubleshoot tastes and odors in drinking water

Follow these troubleshooting steps to determine what's causing the taste or odor issue, what you can do to resolve it, and when to report the issue to us. The information on this page is also in our Customer Guide to Water Quality and Pressure:

Step 1: Compare hot and cold water.

  • If hot water smells bad, but cold is normal: Your home's water heater or hot water plumbing may be the source of the taste/odor. Your water heater may need maintenance. Steam rising from your sink drain can also cause odors (see Step 2).
  • If only the cold water tastes or smells bad, or both hot and cold are abnormal: Continue to Step 2.

Step 2: Fill a clean glass with water and take it into another room to see if the taste or odor persists.

  • If the taste or odor disappears when you move away from the sink: You have a sink drain odor issue. The drain trap or garbage disposal may need cleaning. If a drain odor persists throughout your entire home, there could be a sewer issue in your home or on your street. Call the Bureau of Environmental Services at 503-823-1700 if you think there may be a sewer problem. 
  • If the taste or odor stays with the glass when you move away from the sink: Your sink drain is not the cause of the taste or odor. Continue to Step 3.

Step 3. Check all faucets inside and outside your home.

  • If the taste or odor is present at some faucets, but not all: Your plumbing is the likely source of the taste or odor. Remove and clean faucet aerators or screens. Run faucets to bring in fresh water from the water main (pipe). For some homes with older plumbing, the first flush of water may tend to have a taste or odor.
  • If the taste or odor is at all faucets inside and outside your home: Continue to Step 4.

Step 4: Flush a cold water faucet for one to two minutes to see if the taste or odor resolves.

  • If the taste or odor goes away after you run the water: Your plumbing is the likely source of the taste or odor issue. Remove and clean faucet aerators or screens. Run faucets to bring in fresh water from the water main. For some homes with older plumbing, the first flush of water may tend to have an off taste or smell.
  • If running the water does not improve the taste or odor: Follow the troubleshooting steps below for specific tastes or odors.

Chlorine taste or odor

Blue swimming pool with ladder going down into the water

We treat Portland's drinking water with chlorine to kill harmful microorganisms and make the water safe to drink. We then add ammonia to the water to form chloramines, which make chlorine last longer and better protect public health. The level of total chlorine in your drinking water is safe to consume.

Some people are sensitive to chlorine taste and odor, and chlorine levels can fluctuate slightly throughout the year. You might taste or smell chlorine because of...

  • Seasonal changes: During the warmer months, water temperature rises. It's easier for chlorine to escape warm water than cool water. To adjust, we increase the treatment level of chlorine slightly in the summer and decrease chlorine slightly in the winter. If you taste or smell chlorine, it may be due to normal seasonal fluctuations.
  • Water age: The amount of chlorine in water decreases over time. Every day is slightly different in the water system, and water may take a longer or shorter time to reach your home from the treatment plant. You might taste more chlorine if the water took less time than usual to reach your home.
  • Flushing of water mainsWe may have flushed hydrants to clean water mains in your neighborhood. Flushing water mains improves water quality and brings in fresh water with slightly higher chlorine levels.
  • Personal sensitivity: Some people are sensitive to chlorine taste and odor and notice it when others do not. If your skin is sensitive to low levels of chlorine, talk to your health care provider.
  • Adjusting to different water: Different water systems use different amounts of chlorine to treat their water. If you moved to Portland from another area or are visiting from out of town, the water may taste different from what you're used to. Give yourself a week or two to adjust to the new taste.
  • Medication: Some medications may cause you to have a change in taste or smell, which could impact how your tap water tastes or smells. Talk to your health care provider if you're concerned about a medication's side effects.
  • Water quality changes: Chlorine can interact with organic material, such as sediment in a water main. This can lead to off tastes and odors in drinking water. If you think this may be happening at your house, run your cold water for two to three minutes at each faucet. Contact the Water Quality Line if the issue persists. 

To reduce chlorine taste and odor, you can filter your water or add slices of lemon or Vitamin C (ascorbic acid) to water in a drinking glass or pitcher. Boiling water or letting the water sit out for 24 hours may help slightly, but are not the best options in Portland since we have chloramine (not free chlorine) in our water. 

If you have aquatic pets (such as indoor or outdoor fish, reptiles, shellfish, or amphibians), you should use a chloramine remover for their water.

Earthy, sulfurous, and other tastes or odors

Earthy or musty

brown blocks to signify blocks of dirt or earth

If your water tastes or smells earthy or musty, remove and clean aerator screens and run faucets to see if the taste or smell clears. If the taste or smell persists in all cold water faucets, even after you run the water for a few minutes, report the issue to the Water Quality Line.

Sulfur or rotten eggs

a cracked egg shell with a yellow glow radiating out from it

A sulfur or rotten egg odor in drinking water is typically caused by water heater issues or bacteria in sink drains. Clean your sink drains and garbage disposal. If only the hot water smells, you may need to service the water heater. If all cold water faucets smell and the odor doesn't clear after you run your faucets for two to three minutes, contact the Water Quality line.


Drawing of white crystals

Some people may notice a mineral taste when we're using our groundwater source. Groundwater from the Columbia South Shore Well Field has higher dissolved minerals (such as calcium and magnesium) than Bull Run surface water. Bull Run water is our primary water source, and we only use groundwater as needed, sometimes just one week a year. So if you notice a difference, it could be because you're used to Bull Run water. Contact the Water Quality Line for more information about groundwater.

Metallic or bitter

Drawing of a copper pipe in an S shape

Metallic and bitter tastes are often due to old iron pipes inside homes. Remove and clean aerator screens, and run faucets for one to two minutes to see if the taste or odor clears. Contact the Water Quality Line to request a free metals test kit or to report a taste or odor issue that doesn't clear after you run your faucets.

Fishy, fruity, floral, or grassy

Drawing of a blue fish, orange flower, and purple plum.

Seasonal changes in algae and other organic matter can change the smell or taste of drinking water. Bull Run surface water is unfiltered, and algae populations (which are harmless) increase in the summer. We monitor changes in algae populations. Home water filters can address seasonal taste and odor issues. Contact the Water Quality Line if the issue persists.

Other tastes or odors

Drawing of a beaker with white liquid and white bubbles.

If your water smells like something not listed above, report the issue to the Water Quality Line.