You can fix this
Likely cause: grease and food buildup in the kitchen drain
Kitchen sinks slow down when grease, food residue and coffee grounds build up in the trap. Plunge it, then clean the P-trap if you need to.
Why this happens
Drano says kitchen sink clogs are most often a buildup of food residue, grease, soap scum and other debris in the drain. Family Handyman says clogs in the P-trap and trap arm most often happen when grease or coffee grounds build up. Hot water does not make grease go away: the Texas Commission on Environmental Quality says hot water melts fats, oils and grease off the dishes and into the pipes, where the water cools and the grease may clog them.
How to fix it
- Has drain cleaner gone into the sink? Then do not plunge it, snake it or open the trap. Family Handyman says the chemicals can cause serious burns if they splash on your skin. Call a plumber and say what you used.
- If the slow side has a garbage disposal, Family Handyman says to plunge that side first. If the disposal only hums when you switch it on, it is probably jammed: switch it off, unplug it and use the disposal troubleshooter. Never reach into a disposal.
- If a dishwasher drains into this sink, tighten a clamp over the flexible part of its drain hose before you plunge. Family Handyman says this keeps dirty water from flowing back into the dishwasher.
- Add enough water to cover the plunger cup. On a double sink, hold a wet rag tightly over the other drain.
- Plunge up and down vigorously, and pop the plunger off the drain on the last upstroke. Family Handyman says to expect splashing and to wear rubber gloves and safety glasses.
- If the sink drains well now, take the clamp off the dishwasher hose and you are done. Still slow? Turn off the water supply to the sink, as Bob Vila advises before opening a trap. Close the shutoff valves under the sink by hand. If one will not turn, do not force it. Leave it alone and keep the faucet off instead. Either way, do not run the dishwasher or the disposal while the trap is off. Sponge the water out of the basin and set a bucket under the trap. Loosen the slip nuts gently, lower the trap and clean it out. Family Handyman says to replace a trap that has cracks or weak walls.
- Put the trap back hand-tight plus a quarter turn with pliers, take the clamp off the dishwasher hose, turn the water on and check for drips.
- Keep grease out of the drain from here on. Charlotte Water says to drain grease or cooking oil into a can, let it cool and toss it, then wipe the pan with a paper towel. The Texas Commission on Environmental Quality adds that a disposal does not remove grease, it just makes the pieces smaller.
When to stop. If a slip nut will not loosen without force, or the pipes look old or corroded, stop and call a plumber. If the trap was clear and the sink is still slow, the clog is farther down the line.
If this does not fix it, tell the plumber
- Only the kitchen sink is slow. Other drains are fine.
- Whether it is a single or double sink, and whether it has a disposal or a dishwasher connection.
- You plunged it and cleaned the P-trap, and what you found inside.
- Whether any drain cleaner went down this drain, and which one.
Build the full list: what to tell the plumber.
Start this troubleshooter over
- Family Handyman: How to clean and unclog a kitchen sink drain
- Drano: How to unclog your kitchen sink in 3 steps
- Texas Commission on Environmental Quality: Reducing fats, oils, and grease in your home or apartment
- Charlotte Water: Flow Free
- Bob Vila: How to fix a slow sink drain
- Lowe's: Unclog a sink, shower or tub drain
- Family Handyman: How to clear clogged drains
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