Sink faucet keeps dripping (leak is at spout or base)

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

1. Check 1

   Dry the spout, spout joint, faucet deck, handles, and the area below the sink. Turn the faucet on briefly only if the leak is controlled, then turn both handles fully off and watch with a tissue for the first place that becomes wet.

   Expected result: Record whether water exits the spout end after shutoff, appears at the spout-to-body joint while running, appears at the base where the faucet meets the sink, comes from a handle, or drips below the sink.

   Next step: Use the observed first wet point to select the matching branch and do not buy a part until the faucet model and water-shutoff condition are known.

   Stop if: Stop immediately if water is spraying, the cabinet is flooding, the floor becomes slippery, or water reaches an electrical outlet, disposer connection, or appliance cord.

   Why this matters

   Why: A post-shutoff spout drip makes the valve or cartridge more likely. A base leak only during flow makes body seals or O-rings more likely; a continuous base leak can involve the valve, cartridge, check valve, spacer, or another internal seal. A leak under the sink may be a supply or mounting connection rather than the spout.

2. Check 2

   With the faucet off, wait long enough to distinguish residual water from a continuing drip. If the leak is at the base, repeat the observation once with water running and once immediately after shutoff; do not leave the faucet running unattended.

   Expected result: Record a few residual drops that stop, a drip that continues with handles off, a base leak only during running water, or a base leak that continues after shutoff.

   Next step: Keep the handles closed and follow the model-identification check. If the drip is continuous or increasing, use the local shutoff before any further inspection.

   Stop if: Do not keep cycling the handles to test a worsening leak, and stop if the faucet cannot be shut off at the handle or supply valves.

   Why this matters

   Why: A leak that stops quickly may be retained water rather than a failed valve. A continuing spout drip indicates incomplete shutoff; Kohler describes a base leak during operation as a different seal pattern from a constant base leak after shutoff.

3. Check 3

   Record the faucet brand and model number if it is safely visible, along with one or two handles, pull-down or fixed spout, swivel behavior, and any separate spray or touch controls. Use the manufacturer model or parts guide rather than appearance alone.

   Expected result: Record a confirmed model, an uncertain model, no readable model information, or a faucet assembled from mixed or aftermarket components.

   Next step: Use the confirmed model's instructions to decide whether an owner repair is appropriate. If identity remains uncertain, request a plumber or manufacturer support diagnosis before disassembly.

   Stop if: Do not infer compatibility from brand, color, handle shape, or a part that merely looks similar, and do not remove the handle just to identify a cartridge unless the model instructions support that step.

   Why this matters

   Why: A confirmed model can map the symptom to the correct valve, cartridge, stem, seal, or spout parts. An uncertain or mixed identity means a visually similar replacement may not fit; Moen and Delta both direct users to model-specific identification for parts.

4. Check 4

   Before any model-approved work on a handle, spout, valve, cartridge, or seal, close the faucet's hot and cold supply valves and open the faucet briefly to verify that pressure has dropped. Keep a towel or pan below the connections.

   Expected result: Record both supply valves closed and flow stopped, one valve that will not close, continued flow, a seized or corroded valve, or no accessible local shutoff.

   Next step: Proceed only with the exact manufacturer's instructions when isolation is confirmed. If either supply cannot be shut off or the faucet remains pressurized, close the main supply only if you know its safe operation and arrange a plumber; otherwise stop and keep clear.

   Stop if: Never force a supply valve, loosen a fitting under pressure, or remove a pressurized cartridge, spout, or hose.

   Why this matters

   Why: No flow and contained residual water indicate the faucet is isolated for the next model-specific step. Continued flow or a failed shutoff leaves the fixture pressurized and makes disassembly unsafe; a local shutoff problem may require plumbing service.

5. Check 5

   With water isolated, inspect the outside of the spout joint and faucet base for scale, a visibly displaced seal, looseness, or a wet trail. Do not pry the spout, force a set screw, remove a retaining nut, or scrape inside a valve unless the exact model instructions identify the tool and sequence.

   Expected result: Record a base leak only while running, continuous base wetness, a loose or swiveling spout with water at the joint, dry exterior surfaces, or corrosion that prevents safe access.

   Next step: Use a model-specific seal or valve procedure only if it is explicitly suitable and the shutoffs remain closed. Otherwise document the result and call a plumber.

   Stop if: Stop for corroded or seized hardware, a faucet that moves in the countertop, water under the deck, a hidden leak, or any need to use force or remove the faucet from the sink.

   Why this matters

   Why: A running-only base leak supports an O-ring, bearing, or body-seal path; a continuous base leak can support a valve, cartridge, check valve, spacer, or other internal seal path. Corrosion or a dry exterior means the visible base may not be the source.

6. Check 6

   Compare the spout outlet and the base with a dry tissue after the water is isolated and again after a model-approved repair or service has restored water. Do not use the faucet as a prolonged leak test or leave the cabinet open unattended.

   Expected result: Record a dry spout with a wet base, a continuing outlet drip, no leak, or water appearing at a different location such as the handle, hose, or supply connection.

   Next step: Close the supply and arrange service if any drip remains, moves under the sink, or returns after a short controlled check. Record the new location for the technician.

   Stop if: Stop testing for any spray, rapidly growing puddle, wet cabinet floor, damage to cabinetry, or water near electrical equipment.

   Why this matters

   Why: A continuing outlet drip points back to the valve or cartridge path; a dry outlet with a wet base points to spout seals or the base connection. A changed leak location can indicate a disturbed seal or a separate supply problem and should not be treated as proof of a successful repair.

7. Check 7

   Prepare a service handoff with the faucet model, handle type, first wet location, drip timing, supply-valve behavior, visible corrosion or looseness, whether water appears under the sink, and any previous cartridge or seal work. Do not disassemble further to gather information.

   Expected result: Confirm that the record describes observations rather than an assumed failed part and includes photos only of dry, safe, externally visible areas.

   Next step: Request qualified plumbing service when the leak persists, the model is unknown, shutoffs fail, or repair requires handle, cartridge, spout, supply, or countertop access beyond the manual's safe scope.

   Stop if: Stop all owner troubleshooting when the next step requires pressurized disassembly, force, cutting, soldering, faucet removal, concealed plumbing access, or work near electrical equipment.

   Why this matters

   Why: The timing and location help a plumber distinguish a valve or cartridge leak from spout O-rings, base seals, mounting or supply connections, and prevent a wrong model-specific part from being installed.