Kitchen Sink Plumbing Problems and How to Fix Them

Start with the symptom

Most kitchen sink problems fall into a handful of groups. Matching what you see to the likely cause saves time and keeps you from taking apart pipes that are fine.

If you are new to how the pieces fit together, what plumbing a kitchen needs explains supply lines, drains, vents and shut-offs.

Slow or blocked drains

A slow drain is usually the early stage of a clog. Cooking grease cools and sticks to the inside of the pipe, then catches food particles and soap residue. Over time the passage narrows.

Start with the easy steps: clear the strainer, flush with hot tap water and dish soap, and try a plunger. If that does not help, the P-trap (the curved section under the sink) is the next place to look. The full process is in our guide to fixing a kitchen sink that drains slowly.

If the trap is clean and the sink still will not drain, the blockage is probably in the pipe going into the wall or further along. That is covered in what to do when the clog is past the P-trap.

Signs that a blockage is bigger than one sink include other fixtures draining slowly, gurgling sounds, or water backing up in a different drain. In that case the problem may be in a shared line, and a plumber is a sensible next call.

Leaks under the sink

Leaks under a kitchen sink are common because the cabinet holds many connections: supply lines, shut-off valves, slip nuts, the drain basket, and often a disposal and dishwasher hose. Water can run along a pipe and drip from a point far from the actual source, so dry everything and watch to see where moisture first appears.

Our guides cover the details:

• How to find and fix a leak under the sink for a step-by-step approach to tracing the source.
• Why your kitchen sink is leaking from the bottom for the usual suspects around the basin, drain and faucet.

Even a slow leak can swell and damage the cabinet floor and encourage mold, so it is worth addressing sooner rather than later.

Garbage disposal problems

Disposals can jam, hum, or leak. A leak is the most common reason people look for help. Before you do anything beyond looking, turn the disposal off and unplug it if you can reach the plug safely. Never put your hand in a disposal. If water is near the electrical connections, leave it alone and call a licensed professional.

Many apparent disposal leaks actually start higher, at the sink flange, the discharge pipe, or the dishwasher hose. See garbage disposal leaking from the bottom for how to tell the difference and when replacement makes sense.

Faucet drips and low flow

A dripping faucet often means a worn internal part, such as a cartridge, washer, or seal. The exact repair depends on the faucet type and brand, so check the manufacturer’s instructions or parts diagram. Turn off the water at the shut-off valves under the sink before disassembling anything. A drip that seems minor adds up, as shown in how much water a dripping faucet wastes.

Low flow at the faucet can come from a clogged aerator (the screen at the tip of the spout), partially closed shut-off valves, or sediment in the lines. Unscrewing and rinsing the aerator is a low-risk first step. If pressure is low throughout the house, the cause is likely beyond the sink; see how to fix low water pressure.

What plumbers use instead of chemical drain cleaners

Many plumbers prefer mechanical methods: a plunger, a hand-held drain auger (snake), or professional equipment such as a motorized cable machine or a camera to inspect the line. These remove the blockage rather than dissolving part of it.

Chemical drain cleaners are controversial. They can be hazardous to skin and eyes, can produce harmful fumes, and should never be mixed with other products. If a chemical cleaner fails and leaves standing water in the sink, the water may be caustic, which is a safety concern for you and for anyone who later works on the pipes. Read and follow the label, and tell your plumber if you used one.

Tools worth owning

A small kit handles most simple jobs:

• A cup plunger
• A bucket and old towels
• Adjustable pliers or a pipe wrench
• A flashlight
• A hand-held drain auger

Prevention habits

• Wipe grease from pans and put it in the trash instead of rinsing it down the drain.
• Use a sink strainer to catch food scraps.
• Run plenty of water when using the disposal, and avoid fibrous or starchy scraps such as potato peels.
• Occasionally flush the drain with hot tap water.
• Look under the sink every so often for damp spots, stains, or a musty smell.

When to call a professional

Call a plumber if:

• Multiple drains are slow or backing up.
• The clog does not clear after reasonable mechanical attempts.
• You cannot stop a leak, or cannot shut off the water.
• The leak involves a disposal or other electrical equipment near water.
• You smell sewage, or the cabinet floor is soft or moldy.
• You smell gas anywhere. Leave the house, avoid switches and flames, and call your gas utility or emergency services from outside. Do not attempt a gas repair yourself.

FAQ

What should I do if my kitchen sink is not draining at all? Remove standing water if needed, clear the strainer, and try a plunger. Then clean the P-trap. If that fails, see the clog past the P-trap guide.

Do baking soda and vinegar really unclog drains? They can help with light odors or minor film, but they are not reliable for solid clogs. See the slow drain guide for a more dependable order of steps.

What are common bathroom plumbing issues? Many are similar, such as slow drains and leaks under the vanity, but this guide focuses on the kitchen.