Sink Running: Find the Water Path, Isolate the Supply, and Stop the Leak Safely

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

1. Check 1

   Close the faucet handle or handles normally and watch for several moments without forcing them. Look at the spout, handle or stem, faucet base, supply hoses and shutoff valves under the sink, and the cabinet floor. Keep hands away from wet electrical equipment and do not reach into an inaccessible opening.

   Expected result: Water may continue from the spout, appear only around a handle or stem, bead at the faucet base, spray from a supply connection, or collect below the sink while the spout is dry.

   Next step: If water is at a pressurized connection or spreading, isolate the supply before further inspection. If it is only a controlled faucet leak, continue to identify whether it is at the handle, stem, or spout.

   Stop if: Do not keep operating a faucet with a burst hose, uncontrolled spray, damaged pipe, or water near electrical equipment.

   Why this matters

   Why: The leak location determines the next check. Continuous spout flow points to the faucet's closing mechanism; handle or stem moisture points to a seal or packing area; a supply connection or cabinet-floor leak may be a pressurized plumbing failure rather than a faucet repair.

2. Check 2

   Find the hot and cold water shutoff valves under the sink if they are accessible and clearly identified. Turn the affected valve clockwise gently until it stops; do not force a stiff valve. If there are no usable local valves, use the home's main water shutoff only if you know its location and can operate it safely.

   Expected result: The flow may stop, slow to a drip, or continue unchanged. A valve may be missing, seized, visibly corroded, or connected to a hose that moves when the valve is turned.

   Next step: If the flow stops, leave the affected valve closed and proceed with a safe faucet-location diagnosis. If it does not stop or the valve is unsafe to operate, shut off the main only if safe and arrange plumbing service.

   Stop if: Do not use pliers, a wrench, heat, or force on a stuck shutoff valve or pressurized fitting.

   Why this matters

   Why: A closed local valve that stops the flow isolates the faucet and prevents further water waste while it is repaired. Continued flow means the wrong valve may have been closed, the valve may not seal, or another supply path is involved; forcing it can cause a larger leak.

3. Check 3

   With the local supply isolated and the area dry, determine whether the water was at the spout, handle, stem, or faucet body. If the leak is from the spout with the handle fully closed, note whether the faucet has one handle or separate hot and cold handles. If it is around the handle or stem, do not remove parts until the exact valve type and model are known.

   Expected result: A spout may keep dripping or running, a handle may leak only while the faucet is open, or the stem and faucet body may stay wet after the flow is isolated. The leak may be on one side of a two-handle faucet or on the single control.

   Next step: Use the observation to tell the plumber which faucet section is affected. Only attempt a user repair when the supply is isolated, the faucet type is known, and the manufacturer's instructions support it; otherwise keep the valve closed and arrange service.

   Stop if: Do not force a handle, strike it, overtighten packing hardware, or remove a faucet stem from a pressurized line.

   Why this matters

   Why: EPA notes worn washers and gaskets as common faucet leak causes. Portland's guide maps handle leaks to the packing area, stem leaks to an O-ring, and outlet leaks to the lower stem washer; a single-handle cartridge or valve body can require a different model-specific procedure.

4. Check 4

   Inspect the supply hoses, shutoff-valve connections, faucet mounting area, trap, drain tailpiece, and overflow area with the cabinet dry. Use a towel to identify the first place that becomes wet, but do not loosen a connection to test it. If the leak is from a drain joint rather than the faucet, do not treat it as a running faucet valve problem.

   Expected result: Water may appear at a hose nut or shutoff valve, beneath the faucet mounting point, at a trap or drain connection, or only at the sink rim or overflow. The first wet point may be higher than the puddle.

   Next step: Keep the relevant supply valve closed for a supply leak, avoid using the sink for a drain or overflow leak, and arrange plumbing service if the connection is corroded, inaccessible, or still wet after isolation.

   Stop if: Do not use the sink when water is entering cabinetry, a wall, flooring, or electrical equipment.

   Why this matters

   Why: A pressurized supply leak can continue whenever the valve is open and needs a different isolation and repair path from a faucet-spout drip. A drain or overflow leak may occur only while the sink is draining or filled, so the trigger matters.

5. Check 5

   Prepare a repair handoff after isolating the water. Record the faucet brand and model if visible, one or two handles, hot or cold side, whether the flow is a drip or steady stream, exact leak location, whether the local valve closes, and whether the leak returns when the valve is reopened. Do not order a washer, O-ring, cartridge, or valve by appearance alone.

   Expected result: The repair may be a simple seal or washer, a cartridge or valve assembly, a supply hose or shutoff valve, a drain connection, or a hidden pipe leak. The model or valve type may be unknown.

   Next step: Give the recorded details to a licensed plumber or the faucet manufacturer support channel. Keep the local or main supply closed until the leak is repaired if reopening it causes a continuing flow or unsafe leak.

   Stop if: Do not dismantle hidden piping, use incompatible seals, or leave a repaired connection unattended while water is restored.

   Why this matters

   Why: A part name cannot be established from the symptom alone. The leak location and faucet design determine compatibility, and complicated or pressurized plumbing repairs can cause property damage if performed incorrectly.