Sink repair: what to know

What the job involves, what changes the price, and what to ask a pro.

What sink repair is

Sink repair fixes a sink that leaks, drains slowly, drips from the faucet or has loose fittings. Many repairs are a worn washer, a cracked or clogged trap, a worn cartridge, or a loose supply connection, which a pro can often fix without replacing the sink.

Signs you need it

  • Water drips from the trap, the slip nuts, or the drain joint when the sink is in use
  • The sink drains slowly, or it gurgles when the other sink runs
  • The faucet drips, or the handle is loose at the base of the sink
  • Water stains or a soft cabinet floor under the sink, which can mean a slow leak
  • The sink moves or rocks, or the drain flange has come loose from the bowl

What the pro does

  • Check the trap, the slip nuts and the washers for wear, cracks and misalignment, and replace the parts that leak
  • Clear the drain and check the tailpiece and the outlet for clogs or cracks
  • Check the supply connections, the shutoff valves and the braided lines under the sink
  • Check the drain flange and the sink mounting for looseness, and reseal or retighten where needed
  • Replace the worn cartridge or washer in the faucet, if the faucet is the source of the drip
  • Test the drain and the supply under water, and check every joint for drips before you leave

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Source of the problem: a washer or slip nut is simple, while a cracked sink bowl or a rotted cabinet is not
  • Condition of the trap, since old plastic traps crack and need replacing
  • Whether the shutoff valves need replacing to make the repair
  • Access under the sink and whether the disposal or the dishwasher has to be moved
  • Sink material and whether a crack can be repaired or the sink must be replaced
  • Whether water damage to the cabinet or floor has to be repaired separately

What a written quote should spell out

  • Source of the leak or drain problem, and how it was found
  • Parts replaced, such as the trap, the slip nuts, the washers or the supply lines
  • Whether the faucet, the valves or the drain flange are repaired or replaced
  • Test method, and whether the drain was cleared
  • Any damage found in the cabinet, and who handles it

Questions to ask before you hire

  • Where is the leak coming from, and how did you confirm it?
  • Is the trap cracked, or only the slip nut loose?
  • Will you check the supply lines and the shutoffs while you are under the sink?
  • Can the sink bowl be repaired if it is cracked, or does it need replacing?
  • Will you test the drain under water before you leave?
  • If the cabinet is damaged, will you show me the damage and the repair?

Red flags

  • Pro who replaces the entire sink for a leaking trap or a slip nut
  • Pro who uses plumber's tape on a slip nut joint, where a washer is needed
  • Pro who ignores water damage in the cabinet and does not show it
  • Pro who leaves the drain without a water test

What you can do yourself

A homeowner can tighten a slip nut, clean a trap, or replace a worn washer on a trap or supply connection. Call a pro if the leak is at the supply shutoff, if the cabinet floor is soft, or if the sink bowl is cracked, since a leak under the sink can run into the floor and the subfloor without being noticed.

Licenses and permits

Sink repair on the drain and supply lines is commonly licensed plumbing work, while simple washer and trap changes are sometimes done by a general contractor or the homeowner. Check with your state or local licensing agency about what applies to your work.

Sink repair questions

How do I know if the trap or the faucet is leaking?

Dry the joints under the sink and run the faucet for a minute. A leak at a slip nut or a trap bend is from the drain side. A leak from the handle or the base of the faucet is from the faucet.

Can a cracked sink bowl be repaired?

Some cracks can be sealed, and the pro can tell you whether the crack is stable. A crack that runs to the drain or the rim usually means replacement, since the seal will keep failing.

Why does my sink drain slowly after a repair?

A clog in the trap or the tailpiece is the most common cause. Check the trap and clear it before assuming the drain line is the problem.

Should I replace the slip nuts and washers during a repair?

Yes, when they are cracked or brittle. Old washers flatten and leak, and they are quick to replace while the trap is off.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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