Sink leaking underneath, (cabinet floor is wet)

Use only checks that match the exact appliance or system and its official guide.

1. Check 1

   Remove stored items, close both accessible faucet stop valves, and place a container or towels under the plumbing. If there is water near a disposal cord, outlet, appliance wiring, or a hot or damaged electrical component, do not touch it; leave electrical isolation to a qualified person.

   Expected result: Record whether the flow stops after the stop valves close, whether water is a slow drip or spray, how far the cabinet floor is wet, and whether any electrical equipment or outlet is wet.

   Next step: Keep the stops closed and arrange urgent plumbing or electrical help for a spray, unclosable valve, wet electrical equipment, or unsafe access. If the cabinet is dry enough to work safely, continue with a paper-towel trace.

   Stop if: Do not touch wet electrical parts, run the disposal, repeatedly open a leaking stop, or work in standing water.

   Why this matters

   Why: A leak that stops when the stops close is on the faucet supply side or residual fixture path; continued flow can be stored water, a valve that is not shutting, or another supply. Water near electrical equipment changes this from a routine plumbing trace to a safety boundary.

2. Check 2

   With water isolated, wipe the faucet supply hoses and stop valves, faucet shank or base, sink drain flange, tailpiece, trap, disposal mounting and discharge connections, and dishwasher hose connection completely dry. Use separate paper towels at each joint.

   Expected result: Identify the first wet towel at a hot or cold supply, stop valve, faucet base or hose, drain flange, tailpiece or trap, disposal, dishwasher hose, cabinet wall, or nowhere visible.

   Next step: Photograph the first wet point and choose the matching branch below. Do not disconnect hoses or loosen a drain nut merely to prove the source.

   Stop if: Do not use a heat source to dry the cabinet, probe seals with a sharp tool, or pressurize a visibly cracked hose.

   Why this matters

   Why: The first wet point is more reliable than the wettest section of floor. A supply or faucet-base leak is pressurized; a drain, disposal, or dishwasher connection usually depends on water use. A dry visible assembly with a wet wall or floor indicates a concealed or adjacent leak.

3. Check 3

   Only when the cabinet, outlet, and visible plumbing are dry, open one stop valve slightly and observe the dry paper towels with the faucet off. If the connection is an accessible quick-connect or threaded fitting, verify only that it is seated as the exact faucet instructions show; do not overtighten.

   Expected result: Record a leak with the faucet unused, a wet stop valve, a wet faucet supply hose or quick-connect, water at the faucet shank or base, or no wetness until the faucet is operated.

   Next step: Close the stops again for any leak, damaged hose, loose valve body, or leak at the faucet base and arrange model-specific plumbing service. If the pressurized path stays dry, proceed to a controlled drain test.

   Stop if: Do not force a stop valve, overtighten a fitting, disassemble the faucet under pressure, or continue if water reaches an outlet or appliance cord.

   Why this matters

   Why: A leak while the faucet is off points to a continuously pressurized stop, supply hose, faucet connection, valve, or seal. A leak only when the faucet is used points toward the faucet body, spray hose, or a connection that moves under flow.

4. Check 4

   With the disposal off and the cabinet area dry, place a container under the drain assembly and add a small amount of water to the sink, then release it while watching the dry towels. If a disposal or dishwasher is connected, do not run the appliance; inspect its accessible flange, tailpipe, and hose connections during the drain event.

   Expected result: Record water at the sink flange, drain gasket, tailpiece, trap joint, disposal mounting or discharge, dishwasher hose or air-gap connection, or no leak during sink drainage.

   Next step: Stop the drain test for a spray, fast drip, or cabinet-floor overflow. Keep the disposal and dishwasher off and arrange plumbing service for a wet flange, trap, disposal, dishwasher hose, or inaccessible drain connection.

   Stop if: Do not put hands into a disposal, energize a wet disposal, remove the trap over electrical equipment, or loosen drain connections while water is flowing.

   Why this matters

   Why: A leak that appears only while the sink drains is a drain-side seal or connection problem, not usually a faucet supply problem. InSinkErator identifies sink flange, dishwasher, tailpipe, and mounting connections as leak-test points; a dry drain path shifts attention back to the faucet or a concealed source.

5. Check 5

   Dry the cabinet floor and adjacent wall, then inspect from the cabinet opening for swelling, discoloration, a wet back wall, or water entering from the countertop, dishwasher side, or neighboring plumbing. Check only the sink drain flange and accessible faucet base from below; do not remove the sink, countertop, wall, or cabinet floor.

   Expected result: Record a sound but wet cabinet floor, softened or swollen particleboard, water entering from outside the cabinet, a wet wall with dry plumbing, or a recurring leak whose first point cannot be seen.

   Next step: Keep all sink water use to a minimum and arrange a plumber for a hidden or adjacent leak. Document the cabinet damage after drying and repair or replace damaged materials only after the plumbing is verified dry.

   Stop if: Do not cut the cabinet or wall, remove the sink, drill for inspection, apply sealant over an active leak, or conceal wet wood before the source is repaired.

   Why this matters

   Why: Cabinet damage is a consequence until the source is stopped. Water entering from the wall, countertop, adjacent dishwasher, or a hidden pipe is outside a safe under-sink adjustment; a dry visible assembly with recurring wetness needs controlled professional tracing.