Why is my kitchen sink draining slowly?

Short answer

A slow-draining kitchen sink is almost always caused by grease and food buildup coating the inside of your pipes. Over time, cooking oil, soap scum, and food particles accumulate in the P-trap (the curved pipe under your sink) and restrict water flow. It's rarely a serious plumbing issue and can usually be fixed yourself.

Why it happens

Kitchen drains handle grease and food every day. Unlike bathroom drains, kitchen pipes deal with:

• Cooking oil and fats — these solidify on pipe walls as they cool
• Soap residue — dish soap mixes with grease and creates a thick coating
• Food particles — small pieces that slip past the strainer collect in bends
• Coffee grounds — one of the worst offenders, they clump and don't dissolve

The P-trap (the U-shaped pipe under your sink) is where most clogs form because water slows down in the curve.

How to fix it: step by step

Step 1 — Try boiling water first (free, 2 minutes)

Carefully pour a full kettle of boiling water directly down the drain. This melts grease buildup. Wait 5 minutes, then run the tap. If it drains faster, you're done.

⚠️ Only use boiling water on metal pipes. If you have PVC pipes (white plastic), use hot tap water instead — boiling water can soften PVC joints.

Step 2 — Baking soda + vinegar (free, 15 minutes)

1. Pour ½ cup of baking soda down the drain
2. Follow with ½ cup of white vinegar
3. Cover the drain with a cloth or stopper for 10 minutes
4. Flush with hot water

This fizzing reaction breaks up grease and light clogs without chemicals.

Step 3 — Use a drain snake ($15–$30)

If the above didn't fix it:

1. Remove the drain strainer
2. Insert the drain snake (also called a drain auger) and push it down until you feel resistance
3. Rotate it to catch the clog, then pull it out
4. Run hot water to flush

Step 4 — Clean the P-trap (20 minutes, slightly messier)

If the snake didn't work, the clog is likely in the P-trap itself:

1. Put a bucket under the P-trap
2. Unscrew the two slip nuts by hand (or with pliers)
3. Remove the P-trap and clean it out
4. Reassemble and run water to check

Common mistakes to avoid

• Using chemical drain cleaners (Drano, etc.) — they work short-term but damage pipes over time and aren't great for the environment
• Ignoring it — a partial clog becomes a full clog faster than you'd expect
• Pouring grease down the drain — always dispose of cooking fat in the trash

When to call a plumber

If you've tried all the above and the drain is still slow, the clog may be deeper in the main drain line. That requires professional equipment. Expect to pay $100–$250 for a standard drain cleaning.

Related questions

• Can garbage disposals cause slow drainage?
• How to unclog a garbage disposal
• How to fix a leaky faucet
• Is it safe to use chemical drain cleaners?
• How to unclog a bathroom sink