Grease clogging kitchen drain

Grease buildup restricting kitchen drain pipe

Quick Answer:

If your sink slows after frequent cooking, the likely cause is grease building up and narrowing the pipe. Start by running hot water with a bit of dish soap, then check the P-trap and the piping under the sink. If you find hardened residue or repeated backups, follow the step-by-step checks below before trying stronger measures.

Why This Happens

Grease and cooking oil are liquid when hot but cool and solidify as they travel through the drain. Over time they cling to pipe walls and collect food particles, forming a sticky, narrowing clog. Small slowdowns at first can become full blockages. Repairs or changes near the sink can reveal or worsen an existing buildup, and regular use of the sink for greasy waste accelerates the problem.

Step-by-Step What to Do

Step 1: Clear surface debris and run hot water

  • Remove any visible food scraps or large particles from the sink strainer.
  • Run the hottest tap water your pipes can handle for a few minutes while adding a tablespoon of dish soap. The soap helps dissolve grease and the hot water carries loosened residue toward the drain.

Step 2: Use a plunger

  • Seal adjacent drains if you have a double sink, then plunge the clogged sink with a flange plunger. Several firm pumps can dislodge soft buildups.
  • Empty any standing water into a bucket if needed before removing the P-trap in the next step.

Step 3: Inspect under-sink piping for grease residue

  • Place a bucket under the P-trap where the curved pipe sits. Unscrew the slip nuts and remove the P-trap.
  • Check inside the trap and the horizontal tailpiece for sticky, greasy buildup. Clean them with a brush and hot, soapy water. Rinse and reassemble, checking for leaks.

Step 4: Reach deeper if needed

  • If the clog is past the trap, use a hand-held drain snake (auger) to reach and break up the blockage. Feed the snake slowly and pull back any debris it brings up.
  • A wet/dry vacuum can also remove loosened grease if available and used carefully.

Step 5: Test and prevent recurrence

  • After cleaning, flush the drain with hot tap water while running the disposal (if you have one) for a minute to move any remaining residue.
  • To prevent future clogs: scrape pans into the trash before washing, wipe greasy pots with a paper towel first, and avoid pouring fats or cooking oil down the sink.

Extra troubleshooting

  • If the slowdown follows heavy cooking, this is similar to Slow drain after cooking oily foods and usually responds to the steps above.
  • If the problem began right after work on the sink, check seals and connections—this is like Slow drain after installing new faucet, which can introduce alignment issues or loose fittings that let grease collect differently.

What Not to Do

  • Do not ignore recurring grease smells. That odor usually means residue is building inside pipes and will worsen over time.
  • Do not pour grease or hot oil down the drain, even with running water.
  • Do not rely on chemical drain cleaners for grease clogs—many are ineffective on greasy residue and can damage pipes or create hazardous reactions if mixed.
  • Do not use boiling water on PVC piping; very hot water can soften or warp plastic plumbing. Use the hottest tap water instead and repeat if necessary.

When to Call a Professional

  • Persistent clogging after you clean the trap and snake the drain.
  • Multiple fixtures are slow or backing up (sink plus dishwasher or toilet), which suggests a deeper line issue.
  • Signs of a leak, cracked pipes, or if you’re uncomfortable taking apart plumbing joints.
  • Repeated grease buildup despite following prevention steps—ask a plumber about pipe cleaning or a more permanent fix.

Safety Notes

  • Wear gloves and eye protection when working under the sink. Grease and trapped food can be messy and unsanitary.
  • Turn off the water supply if you disconnect piping, and have a bucket handy to catch spills.
  • Do not mix different chemical cleaners. If a chemical drain cleaner has been used, ventilate the area and wait before attempting manual cleaning or calling a pro.

Common Homeowner Questions

  • Why did the sink slow down after cooking? Grease from food cools and sticks to pipe walls, narrowing the drain.
  • Will pouring hot water and soap always fix it? It helps soften fresh grease but won’t remove hardened buildup deep in the pipes.
  • Can I put grease in the trash? Yes—wipe pans with a paper towel or let grease solidify in a disposable container before throwing it away.

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