Leaking faucet: find the leak and choose the right next step

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

1. Check 1

   Dry the spout, handles, base, sink rim, visible supply connections, and the cabinet floor. With the drain open and hands clear, turn the faucet on briefly, then turn it off and watch from a dry position; use a paper towel only on accessible exterior surfaces to identify the first returning wet point.

   Expected result: Water returns from the spout while the handles are off, appears around a handle or stem, pools around the base, or starts at a supply fitting, hose, or faucet body under the sink.

   Next step: Record the location and whether it occurs with the faucet off or only while flowing, then shut off the fixture supply before any disassembly. If water is entering a wall, cabinet, or electrical area, isolate it and escalate.

   Stop if: Stop the test for a spray, rapidly increasing flow, water near electrical equipment, a damaged hose, or a leak whose source cannot be observed without removing the cabinet or wall.

   Why this matters

   Why: The first wet point narrows the repair path: valve or cartridge for an off-state spout drip, handle or stem seal for a handle leak, base seal or body path for a base leak, and connection or hose service for an under-sink leak.

2. Check 2

   Close the hot and cold fixture shutoff valves under the sink by their normal operating motion, then open the faucet briefly to confirm pressure is relieved. If the valves cannot be found or do not stop the flow, close the house main and leave the local valves untouched for a plumber.

   Expected result: The faucet stops supplying water after the fixture valves close, or water continues because a valve is stuck, missing, inaccessible, or the leak is upstream of the fixture valves.

   Next step: Place a towel or container below a small residual drip and proceed only after the fixture is isolated. Do not use pliers on a seized valve, remove a supply line under pressure, or reopen the water until the work area is secure.

   Stop if: Stop for a valve that twists without stopping flow, a cracked valve or pipe, a burst or bulging hose, a continuous spray, or water that cannot be contained.

   Why this matters

   Why: A successful local shutoff contains the fixture for diagnosis; an unsuccessful shutoff increases water-damage risk and means the next step is isolation at the main and professional plumbing service.

3. Check 3

   After isolation, dry the faucet again and make one controlled observation with the handles in the off position, then—only if the supply is safely controllable—observe the exterior handle and stem area during a brief flow. Do not remove a handle or retaining nut yet.

   Expected result: A drip continues from the spout with the faucet off, or water appears at the handle, stem, or base only while that handle is operated; on a two-handle faucet, one side may be the source.

   Next step: Identify the faucet style and model before selecting a cartridge, stem assembly, washer, O-ring, seat, or spring. If the leak path is unclear or the retaining hardware is corroded, arrange service instead of prying or forcing it.

   Stop if: Stop for a handle that is loose at the body, a cracked finish or casting, a seized fastener, a valve that will not isolate, or water emerging from inside the wall or cabinet.

   Why this matters

   Why: An off-state spout drip suggests a valve seal, cartridge, seat, spring, or stem path; a handle or stem leak suggests a packing or O-ring path; one affected side may be repairable without changing the other.

4. Check 4

   With the fixture valves closed and the cabinet dry, inspect the visible supply tubes, braided hoses, connection nuts, faucet mounting area, and hose joints using a light. Do not disconnect a line, put a wrench on two unrelated fittings, or overtighten a connection to test it.

   Expected result: Water begins at a supply connection or hose, runs down from the faucet mounting area, appears at a sprayer connection, or the visible fittings remain dry while the leak is only at the spout or handle.

   Next step: Keep the local valves closed and arrange plumbing service for a wet, damaged, corroded, or inaccessible connection. If the only issue is a clearly loose accessible fitting and the faucet instructions permit adjustment, use gentle hand pressure only and retest with the cabinet visible.

   Stop if: Stop for a bulging or split hose, corrosion flakes, a fitting that turns with the pipe, water in the wall, a connection that cannot be held safely, or any leak that returns immediately after isolation.

   Why this matters

   Why: A connection or hose leak is separate from a valve-seal leak and may flood the cabinet; water from the mounting area can indicate a faucet-base or body seal, while dry connections support the upper-faucet branch.

5. Check 5

   Read the faucet's exterior model information or compare its handle and valve arrangement with the manufacturer's identification guidance, without dismantling it. Record single-handle or two-handle design, room and faucet type, whether the leak is from the spout, handle, base, or connection, and which hot or cold side is implicated.

   Expected result: The faucet design and model can be identified, or the design, model, valve type, or source side remains uncertain.

   Next step: Use the manufacturer's instructions for the identified faucet or give the record to a plumber. Do not substitute a visually similar cartridge or use force to make a different part fit.

   Stop if: Stop for missing identification, a discontinued or modified faucet, concealed valves, corroded hardware, or a need to remove the faucet body or supply lines to identify the repair.

   Why this matters

   Why: A confirmed design can point to a compatible repair family; uncertainty means a washer, O-ring, cartridge, seat, spring, or stem cannot be safely selected from the word leaking alone.

6. Check 6

   After an appropriate repair has been completed under the faucet instructions, reopen the fixture supply valves slowly while keeping the cabinet, connections, handles, base, and spout visible. Operate hot and cold sides separately, then turn the faucet off and watch for residual dripping or a new wet path.

   Expected result: The faucet remains dry with the water off and during flow, or a drip, spray, cabinet leak, or connection leak returns.

   Next step: Close the fixture valves again and arrange service if any leak returns. Do not keep tightening, cycle a damaged valve, or leave the cabinet closed over a wet connection.

   Stop if: Stop immediately for spray, rapid flow, water into the cabinet or wall, a loose faucet body, or a local valve that no longer shuts off.

   Why this matters

   Why: A dry controlled retest supports the repaired leak path; a returning or newly appearing leak means the repair did not isolate the cause, a second component is involved, or a fitting was disturbed.