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Water Odor Guide


Water odor issues are unpleasant and inconvenient, and identifying the underlying issue causing them can be challenging.

What causes a “rotten egg” smell in the water? Sulfate reducing bacteria, which use sulfur as an energy source, are the primary producers of large quantities of hydrogen sulfide. These bacteria chemically reduce naturally occurring sulfates in water into hydrogen sulfide. Sulfate reducing bacteria live in oxygen deficient environments such as deep wells, plumbing systems, water softeners and water heaters. These bacteria particularly flourish in hot water heaters and hot water lines. Chlorine is an effective treatment to prevent the formation of hydrogen sulfide.

However, we hope that this guide will help in resolving an odor issue:

1) Is the odor coming from a sink or other drain in your house?

To confirm if the odor is in the water or not, fill a glass with water and move away from the sink.  If there is no odor in the cup, then the water is not the source of the odor.  In this case, the issue is likely being caused by a dry trap in the drain line or decaying remains in the line. Run clean water into each drain with odor. Pouring a cup of bleach down the drain will also help. Otherwise, proceed to Step 2.

2) Odor coming from all hot and cold water taps (this may occur if the home has been empty for some time):

a. Flush the service line to your home for 15 minutes using an external faucet, then check the water from spigot for odor. If none is present, then flush each faucet for 3-5 minutes. Flushing of hot water taps may require longer to clear.

b. If odor persists in cold water, please contact us at 1-800-248-7689, as we may need to flush the mains in the area.

3) Is the odor coming only from your cold water faucets? (i.e. do you have the odor when running just the cold water?)

a. If “Yes”, is the odor coming from all of the cold water taps in the house?

i. If the odor is coming from all cold water taps:

Flush your home’s service line for 15-20 minutes using an exterior faucet, then check the spigot water for odor. If none, then flush each internal faucet for 5 minutes. If the odor persists, please contact us at 1-800-248-7689 as we may need to flush the water mains in the area.

ii. If the odor is coming only from certain (i.e. not all) cold water faucets:

Flush the affected cold water taps for 5 minutes and check again for odor.

4) Is the odor coming from hot water taps?

a. If odor is coming from all hot water taps:

Run each hot water faucet for 5 minutes and see if that resolves the issue. If not, a full flush of the hot water heater may be necessary. Given the wide range of water heater models, please consult the owner’s manual for instructions on how to drain and refill your hot water heater.

b. If odor is coming only from certain (i.e. not all) hot water taps:

Run each affected faucet for 3-5 minutes and recheck.

Download Guide to Controlling Odors in Hot Water Heaters

5) Additional Comments

Another source for this smell may come from water treatment devices such as sediment filters and/or water softeners. These devices may be used to treat a specific faucet or at the water’s point of entry to a house can also be the cause of an unpleasant smell if not maintained properly. Water treatment devices often required regular maintenance such as filter changes. If left alone for long periods of time, they could begin to harbor bacteria or become a place for organic matter to accumulate which would in turn produce an unpleasant smell. Proper maintenance of such devices would likely correct/prevent this problem.