Why your well water smells like sewage, and what to do right now

If you buy something through our links, we may earn a commission. We'd recommend the same thing either way, and we'll tell you when a free option exists. How we make money

Step 1: Stop drinking the water until you know

The Wisconsin DNR says sewage carries bacteria and viruses that can make you sick. Its advice is to stop using the water for drinking, cooking, and bathing until a lab test for coliform bacteria shows it's clear.

Until then, the Minnesota Department of Health recommends bottled water or water from another source you trust for drinking and cooking. Boiling also works for bacteria: Virginia Cooperative Extension says to hold a rolling boil for at least 1 minute. Don't boil it if you know your well has high nitrate or arsenic, since boiling concentrates them.

Step 2: Check whether it's the water or the drain

Penn State Extension notes that a smell at one sink may come from bacteria in the drain. Fill a glass at the tap, walk to another room, and smell the water there.

• The glass smells fine. The drain is likely the source. Penn State says disinfecting the drain removes the odor. You should still test if you're not sure.
• The glass smells too, or every tap smells. The smell is in the water. Treat it as possible contamination until a test says otherwise.

Step 3: Get a bacteria test now

Ask for total coliform and E. coli. Penn State says E. coli is the more serious result, because it means human or animal waste is reaching the water. Wisconsin suggests adding chloride and nitrate tests too.

Your local health department may test for free, the EPA notes. The EPA also suggests calling the health department for next steps if a result is over the limit.

Think about what could let sewage in

Wisconsin's checklist:

• Is your septic system working properly?
• Did the smell start suddenly, especially after heavy rain or snowmelt?
• Does the well have shallow or thin-walled casing pipe?
• Is the well close to a sewer pipe or a leaking sump?
• Is there limestone bedrock near the ground surface?
• Is there an old, unused well on the property that was never sealed?

If the test is positive

Minnesota's steps:

1. Keep using bottled or boiled water for drinking and cooking.
2. Disinfect the well with a chlorine solution. Minnesota says to hire a licensed well contractor or follow its instructions, and Penn State recommends having a well professional do it.
3. Retest after disinfection. Penn State says to test again 10 to 14 days later, then again 2 to 3 months after that.
4. Go back to normal use only after the tests come back clear.

Shock chlorination kills bacteria in the well, and the source still needs fixing. Have the septic system and the well inspected. Penn State lists simple repairs such as a sanitary well cap and extending a buried casing above ground. If bacteria keep coming back, Penn State lists continuous disinfection, such as a UV system, for persistent cases. Penn State doesn't recommend UV when a test shows more than 1,000 total coliform or more than 100 fecal coliform per 100 mL, and Virginia Cooperative Extension says UV works less well on the parasites Giardia and Cryptosporidium.

Use our shock chlorination guide and shock calculator if you're doing it yourself.

If the test is clear, look for iron bacteria

Iron bacteria can also make water smell like sewage, and they aren't a health threat, Wisconsin and Minnesota both say. Look for orange or brown slime in the toilet tank and red stains on fixtures. See our slimy residue page.

When to call a pro

Call a licensed well contractor if the bacteria test is positive, if the smell started after flooding, or if you find an unsealed old well. Call a septic professional to inspect the system. In Wisconsin, only licensed well drillers or pump installers may seal an unused well. Check your state's rules.

Questions people ask