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Fix a Kitchen Sink Leaking From the Base

A leak from the base of the faucet almost always means one thing: the O-rings or the base gasket have failed. This is a DIY fix that takes 30–60 minutes and costs under $20. Do not ignore it — water sitting under the faucet will rot the cabinet floor and breed mould fast.

Step 1 — Confirm the Source (5 min)

  1. Dry everything under the sink with a towel.
  2. Turn the water on and watch closely — does water seep from around the base of the faucet where it meets the counter? That confirms a failed base gasket or O-ring.
  3. If it's coming from the drain or supply lines instead, the fix is different (ask me).

Step 2 — Shut Off Water (2 min)

  1. Turn off the shut-off valves under the sink (clockwise until firm).
  2. Turn on the faucet to release pressure and drain remaining water.

Step 3 — Remove the Faucet (15–20 min)

  1. Use a basin wrench to reach the mounting nuts under the sink — this tool is almost essential for tight spaces.
  2. Disconnect the supply lines from the faucet body.
  3. Lift the faucet out from above.

Step 4 — Replace Gasket / O-rings (5 min)

  1. Inspect the rubber base gasket (sits between faucet and counter). If cracked, flattened, or hard — replace it.
  2. Check O-rings on the faucet body. Coat new O-rings lightly in plumber's grease before installing.
  3. If the gasket is missing or badly damaged and you can't find an exact replacement today, plumber's putty under the base is a solid interim fix.

Step 5 — Reassemble and Test (10 min)

  1. Reseat the faucet, tighten mounting nuts snugly (do not overtighten — cracks the base).
  2. Reconnect supply lines hand-tight then 1/4 turn with wrench.
  3. Turn water back on slowly. Watch the base for 2–3 minutes.

When to call a plumber: If the faucet body itself is cracked, corroded, or over 15 years old — replace the whole faucet rather than patch it. A new faucet install is still an easy DIY job.

Pro tip: Take a photo of your faucet brand/model number (usually stamped on the body under the sink) before buying replacement parts — Moen, Delta, and Kohler all have brand-specific O-ring kits that fit perfectly and cost the same as generic ones.

What you need

Under-Sink Cabinet Mat

Optional but smart — a waterproof liner catches any future drips before they damage the cabinet floor. Cheap insurance.

$12–20
Basin Wrench

Essential — the long-reach jaws are the only practical way to tighten or loosen mounting nuts deep under a sink. Nearly impossible to do this job without one.

$18–30
Universal Faucet O-Ring Kit

Essential — includes multiple sizes to match your faucet's O-rings. Costs under $10 and solves 80% of base leaks.

$8–12
Plumber's Grease (Silicone Grease)

Essential — lubricates new O-rings so they seat properly and last longer. Never use petroleum-based grease; it degrades rubber.

$6–10
Plumber's Putty

Backup fix if you can't source an exact gasket today. Press a rope of putty under the faucet base to create a watertight seal. Not for use on granite/marble (stains).

$5–8
Adjustable Basin Faucet Gasket

The flat rubber ring that sits between the faucet base and counter. Match to your faucet brand if possible; universal versions work for most standard faucets.

$5–10
Adjustable Wrench 10-inch

For disconnecting and reconnecting supply line nuts. A 10-inch gives enough leverage without being bulky in tight cabinet spaces.

$15–25
Plumber's Tape (PTFE Tape)

Wrap supply line threads when reassembling to prevent any slow drips at the connections. A roll lasts years.

$3–5
Plumber's Tape (Teflon)

Essential for any plumbing job. Wraps around threaded connections to prevent leaks.

Adjustable Wrench

The one tool you need for most plumbing repairs. Get a 10-inch.

Bucket

Catches water during repairs. Also useful for mixing, cleaning, carrying parts.

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