A small drip beneath a kitchen or bathroom sink can go unnoticed until the cabinet swells, flooring stains or a musty smell develops. A short visual check every month—and after plumbing work—can help you notice warning signs early. You do not need to dismantle plumbing to perform this basic inspection.
Prepare for a safe inspection
Remove stored items from the cabinet and use a flashlight. Keep the area dry and avoid touching electrical devices or outlets if water is present. Do not put your hands into standing water where electrical equipment may be affected. If you see an active leak, close the fixture shut-off valve only if it is safe and operates normally.
Inspect the supply lines
Look at the flexible hoses connecting the shut-off valves to the faucet. Check for wetness, rust at metal fittings, bulges, cracks, kinks or corrosion. A hose that looks damaged should be replaced promptly with a compatible, correctly rated connector. Do not tighten a connection blindly if you cannot identify where the water is coming from.
Check the drain and trap
Look at the sink strainer, tailpiece, slip-joint connections and P-trap. Mineral deposits, water marks or dampness can indicate a slow leak. Run a little water while watching the joints with a dry paper towel. Avoid overtightening plastic slip nuts; damaged washers or misaligned parts may need replacement.
Look for cabinet and wall warning signs
Check the cabinet floor, corners, back panel and nearby wall for swelling, peeling finish, discoloration or a persistent musty odor. These signs can indicate an ongoing leak even when no drop is visible. Also look for evidence of pests or mold-like growth; do not disturb extensive suspected mold—seek appropriate professional advice.
What you can do about a minor issue
- Dry the cabinet and identify whether moisture returns.
- Place a dry paper towel beneath a suspect joint to help locate a drip.
- Remove and clean an accessible sink stopper if the issue is drainage, not leakage.
- Arrange replacement of visibly damaged supply hoses or worn seals.
- Call a plumber if a leak continues, a pipe is corroded or the source is hidden.
How often should you check?
A quick monthly check is a practical habit for frequently used sinks. Inspect after replacing a faucet, cleaning a drain trap or storing heavy items in the cabinet. Homes with older plumbing, previous leaks or long periods of vacancy may need more frequent checks.
Frequently asked questions
Why does the cabinet smell musty if I cannot see a leak?
Moisture may be coming from a slow connection leak, a failed seal, condensation or a leak inside the wall. Persistent odor warrants a closer inspection.
Can I use tape to stop a leaking drain joint?
External tape is not a reliable repair for a drain connection. The joint may need correct alignment, a compatible washer or replacement parts.
When should I replace braided faucet hoses?
Follow the connector manufacturer’s service-life guidance and replace any hose showing corrosion, bulging, fraying or leakage. A plumber can help choose the correct connector.
