Quick Answer:
A musty smell after a city water outage is often from disturbed organic material or reduced chlorine residual. Start by calling your water utility to confirm whether they are doing line flushing. Run and flush taps for a few minutes, check multiple fixtures, and wait for the utility’s confirmation before making changes to plumbing or adding filters.
Why This Happens
When a city water outage or main repair changes flow or pressure, silt, biofilms and other organic matter that normally sit in the pipes can get stirred up. Flushing by the utility is meant to clear those deposits, but until the process finishes you may smell earthy or musty compounds. Changes in chlorine levels also make smells more noticeable. If you have a private well instead of a public supply, see Earthy smell in well water for different causes and checks.
Step-by-Step What to Do
Step 1 — Call the water utility
- Confirm whether the outage included planned flushing or repairs and ask for the expected flush schedule and advisories.
- Note any boil-water or no-use notices and follow them.
Step 2 — Flush your own lines
- Open a cold-water tap on the lowest level and let it run for 5–10 minutes. Repeat at an upstairs tap if applicable.
- Flush toilets once or twice to move water through the house lines.
- Check the ice maker and refrigerator water; run water until it is fresh and clear before getting ice or drinking water from those sources.
Step 3 — Check fixtures and aerators
- Smell water at different taps (kitchen, bathroom, outdoor hose). If the odor is only at one fixture, remove and clean the aerator and run the tap again.
- If a single faucet smells after cleaning, it may need further attention from a plumber.
Step 4 — Consider recent work in your home
- If you recently had plumbing changes, such as a pressure-reducing valve, that can alter how lines drain and trap particles—see Musty smell after PRV install for details that might apply.
Step 5 — Monitor and wait for utility confirmation
- Give the utility’s flushing 24–48 hours to complete and for the lines to clear. If the utility confirms flushing is done and the smell remains, follow up with them about testing or next steps.
What Not to Do
- Do not install filters before city flushing completes. That can clog or contaminate the new filter and won’t fix the underlying issue.
- Do not pour household chemicals into drains trying to remove smells; that can be unsafe and ineffective.
- Do not assume the smell means permanent pipe damage—confirm with the utility and observe after their flushing is finished.
When to Call a Professional
Contact a licensed plumber or your utility if:
- The odor persists more than 48 hours after the utility says flushing is complete.
- Water is discolored, or multiple household members get sick after drinking tap water.
- The smell is confined to the house even after external lines are cleared—this suggests a problem in house plumbing.
Safety Notes
- If water tastes or smells off, avoid drinking it until you confirm it’s safe. Use bottled water for drinking and cooking if you are unsure.
- Follow any boil-water or safety advisories from your water utility immediately.
- Do not attempt chemical shock treatments or high-strength bleach dosing unless a professional or the utility advises exact amounts and procedure.
Common Homeowner Questions
- How long should the smell last? — Often 24–48 hours after flushing finishes; contact the utility if it lasts longer.
- Can I drink water that smells musty? — It’s safer to avoid drinking until the utility clears the system or you confirm the issue is resolved.
- Will my water filter fix the smell? — Installing a filter before flushing can ruin the filter; wait until the utility confirms lines are clear, then evaluate filtration if odors persist.
For more related articles, see the Musty, Earthy, or Moldy Water Smell hub.