Mold Under the Sink or After a Small Leak
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Quick answer: Fix the leak first, then dry everything. EPA says if wet materials are dried within 24–48 hours, in most cases mold will not grow. Scrub small areas of mold off hard surfaces with detergent and water; a swollen, moldy cabinet floor may need replacing.
⚠ Safety first:
- Wear an N-95 respirator, gloves and goggles without vent holes; for plain detergent and water, household rubber gloves are fine, but use natural rubber, neoprene, nitrile, polyurethane or PVC gloves with bleach or strong cleaners (EPA).
- Ventilate: open windows and doors, and run a fan that exhausts to the outdoors (EPA; CDC).
- Never mix bleach with ammonia or other cleaners; it makes a poisonous gas (CDC; EPA). If you use bleach, use no more than 1 cup of household laundry bleach in 1 gallon of water and follow the label (CDC).
- If you have asthma, allergies or other health concerns, talk to a health professional before cleaning, or have someone else do it (EPA).
Steps: easiest & free first
- Stop the waterFREE · 2 min
Close the shutoff valves under the sink and put a bowl under the drip. See under-sink storage for keeping valves reachable. - Empty and dryFREE · 24–48 h
Remove everything, wipe up water and run a fan into the open cabinet. Dry within 24–48 hours (EPA). - Clean the moldFREE · 15 min
Wearing gloves, goggles and an N-95, scrub hard surfaces with detergent and water and dry completely (EPA). - Fix the leakSHOP
Tighten slip nuts or replace a worn part; see our sink drain guide. Renters: report leaks right away (EPA). - Replace damaged materialPRO
Particleboard that swelled or stays moldy is porous and may need replacing (EPA). Call a pro for anything beyond the cabinet floor.
⚠ When to call a pro: the moldy area is larger than about 10 square feet (roughly a 3 ft by 3 ft patch) or there’s been a lot of water damage; you suspect mold inside walls, behind wallpaper or in the HVAC system (don’t run the HVAC if you suspect it’s contaminated); the water came from flooding, sewage or other contaminated water; or anyone in the home has health or breathing problems (EPA). Hire someone with mold cleanup experience and check references (EPA). Renting? See what you can fix vs. call your landlord.
Helpful supplies
| Item | Why | |
|---|---|---|
| Cabinet drip tray or mat | Makes the next leak easy to spot | Check price [PLACEHOLDER – no affiliate link] |
| N-95 respirator, goggles, gloves | Protection while cleaning (EPA) | Check price [PLACEHOLDER – no affiliate link] |
Generic categories only; check the product label and your home’s needs before buying.