Best of ArtisansUnder-Sink Leak? 6 Places to Check Before the Cabinet Gets Damaged
A damp cabinet can come from the faucet supply lines, drain connections, garbage disposal, dishwasher hose or even water running across the countertop.
Water under a kitchen or bathroom sink does not always drip from the spot directly above the puddle. Water can travel along pipes, hoses and cabinet surfaces before it becomes visible.
1. Faucet Supply Connections
Look where the hot and cold supply lines connect to the shutoff valves and faucet. A slow seep may leave mineral deposits or a damp spot before it forms a visible drip.
2. Drain and Trap Connections
Run water and watch the slip-joint connections around the P-trap and drain assembly. A loose or misaligned connection can leak only when water is flowing.
3. The Faucet Base
Water splashed around the sink can enter around the faucet base or countertop opening and appear below as a plumbing leak.
4. Garbage Disposal Connections
If the sink has a disposal, inspect the sink flange, discharge connection and dishwasher inlet area. Do not place your hands inside a disposal.
5. Dishwasher Drain or Supply Line
A leak may appear only while the dishwasher fills or drains. Check the hose route and cabinet penetrations during a cycle if it is safe to observe them.
6. The Sink Basin Itself
Older sinks, damaged seals or loose drain assemblies can allow water to escape around the basin or drain opening.
Dry the Area Quickly
EPA guidance emphasizes addressing leaks promptly because persistent moisture can damage materials and support mold growth.
Our Practical Take
Place a dry paper towel under each suspected connection and run water for a few minutes. The first towel to become wet often helps narrow the source.
Related Reading
Try our water-meter leak test, review banging pipes, and browse Plumbing.
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