Quick Answer:
Stop the disposal and stop adding water. Grease softens with heat and can move down the line, then re-solidify and cause a partial clog. Do basic checks: remove visible solids, then test hot vs cold water use with the disposal off and with the disposal briefly on (no new food waste) to see if behavior changes. If the sink still backs up or smells like sewage, call a plumber.
Why This Happens
When you grind greasy food, fats and oils can be soft or liquid and can coat the inside of pipes. As that warm grease cools, it sticks to pipe walls and narrows the passage for water. A garbage disposal can break solids into smaller pieces, but it also pushes softened grease farther down where it can re-harden and create a blockage. The result is slow draining that can turn into an overflow while you are running the disposal or washing dishes.
Step-by-Step What to Do
Step 1 — Stop the disposal and stop adding waste
- Turn the disposal off immediately and stop running the faucet if the sink is overflowing.
- Do not feed any more greasy food or other solids into the disposal.
Step 2 — Remove any visible solids safely
- Turn off power to the disposal at the wall switch or breaker.
- Use tongs or pliers (not your hand) to remove large pieces of food from the drain opening.
Step 3 — Test hot vs cold water use to check for grease-related restriction
- With the disposal power off, run the cold tap for 30–60 seconds and observe drainage.
- Next, run hot tap water (not boiling) with a squirt of dish soap for 30–60 seconds and observe whether drainage improves.
- If you want to test the disposal, restore power and run the disposal for only a few seconds while cold water runs, then repeat briefly with hot water and soap—do not grind any food during this test.
- Interpretation: if hot water temporarily clears the flow but it slows again, or if cold water causes faster flow than hot, grease is likely coating the pipe.
Step 4 — Plunge and flush with hot water and dish soap
- Use a sink plunger on the affected basin (seal the other basin if you have a double sink) to try to dislodge a soft blockage.
- Follow plunging with a long flush of hot tap water and dish soap to help dissolve and carry away grease. Do not pour boiling water into PVC.
- If plunging fails and you are comfortable, a manual drain snake can reach a short distance; otherwise stop and call a pro.
Step 5 — Avoid use and monitor
- Do not use the disposal or run heavy water loads (dishwasher, laundry) until the sink drains normally.
- Check other drains in the house—if they back up, the problem may be in the main line and needs professional attention.
What Not to Do
- Do not grind greasy waste to test drainage; grease-related clogs worsen fast.
- Do not put your hand into the disposal or try to reach down the drain without turning off power.
- Do not use boiling water on PVC plumbing—use hot tap water instead.
- Avoid harsh chemical drain cleaners; they can damage pipes and harm you, and they often don’t solve persistent grease build-up.
When to Call a Professional
- Call a plumber if the sink continues to back up after the steps above or if multiple drains are affected.
- Call if you see sewage backing up, have a strong sewage odor, or if water level keeps rising when appliances run.
- If the problem began after a recent city water interruption, see Sink fills after city outage for related help, or if you had the line snaked and now have problems, see Backup after drain snaking.
Safety Notes
- Always switch the disposal off at the breaker before reaching into the sink or removing jams.
- Wear gloves and eye protection when plunging or removing debris.
- Do not mix chemical cleaners with other substances; they can create dangerous fumes.
- If sewage is present or you smell gas, leave the area and call a professional immediately.
Common Homeowner Questions
- Q: Is running hot water a good way to clear grease?
A: Hot water and dish soap can help flush soft grease, but grinding more grease while testing can send it deeper and create worse clogs. - Q: Will a chemical drain cleaner dissolve grease clogs?
A: Generally no—chemicals often fail on heavy grease, can damage pipes, and are unsafe to handle; a plumber is usually a better option. - Q: Can I snake the drain myself?
A: A hand auger can work for minor blockages; stop and call a pro if you can’t reach the clog or if multiple fixtures are affected.