Clear Grease Buildup from a Kitchen Sink Drain

Grease clogs are the most common kitchen sink problem, and they sneak up on you. One day the water drains fine, the next it's backing up. The culprit isn't usually a single meal—it's months of cooking oil, butter, and bacon fat accumulating inside the pipe, where it cools and hardens into a waxy plug. The good news: you can clear it yourself without calling a plumber, and you probably have everything you need already. The key is understanding that grease buildup requires heat and mechanical action, not just any drain cleaner. Done right, your drain will flow freely again in under an hour, and you'll know exactly how to prevent it from happening next time.

1. Boil Water First. Fill a kettle or large pot with at least 2 quarts of water and bring it to a rolling boil. While it heats, remove any visible debris from the drain opening—hair, food scraps, or backed-up water. You want an open drain to work with.
2. Scald the Clog. Carefully pour the entire kettle of boiling water directly down the drain in one steady stream. The heat will melt accumulated grease and push it through. If you hear gurgling or see water backing up, stop and wait 30 seconds before resuming.
3. Deploy the Powder. Measure out one-half cup of baking soda and pour it directly down the drain opening. Don't mix it with water first. The powder needs to make contact with the sides of the pipe.
4. Trigger the Fizz. Pour one cup of white vinegar down the drain immediately after the baking soda. The two will react—you'll hear fizzing and see bubbling up through the drain. This chemical reaction helps break apart grease buildup and loosens debris clinging to the pipe walls.
5. Wait It Out. Leave the drain alone for 30 minutes. Don't run water, don't pour anything else down it. The baking soda and vinegar mixture will continue working on the buildup, and the chemical reaction needs time to penetrate.
6. Flush Again Hard. Boil another 2 quarts of water. After the 30-minute wait, slowly pour it down the drain in a steady stream. This flushes away the broken-down grease and baking soda residue. The drain should now flow noticeably faster.
7. Verify the Flow. Run the kitchen faucet at full hot water for 30 seconds and watch how quickly it drains. Fill the sink and pull the stopper—it should drain completely within 10 seconds. If it does, the clog is cleared. If it's still sluggish, proceed to the P-trap removal.
8. Access the Trap. If the drain is still slow, the grease buildup is in the curved P-trap pipe beneath the sink. Place a bucket under the trap to catch water and old grease. Have a rag ready. Locate the large nut on either side of the curved section of pipe—these are the slip nuts.
9. Unscrew and Lower. Using an adjustable wrench, turn the slip nuts counterclockwise by hand first—they're hand-tight usually. Once loose, unscrew them the rest of the way by hand. Carefully lower the curved section of pipe into your bucket. It will be heavy and full of water. If it drips, the rag will catch it.
10. Punch Through Grease. Tip the P-trap over your bucket and let the water drain out. You'll see a plug of grease inside. Use a plumbing snake, a straightened coat hanger, or a wooden stick to push the grease out into the bucket. Work it back and forth to break it apart. Rinse the inside of the pipe with hot water from the faucet.
11. Reconnect and Seal. Line the pipe back up with the connections above and below it. Hand-tighten both slip nuts first, then use your wrench to snug them down firmly—but not so tight you strip the plastic. A quarter-turn past hand-tight is right. Run water and check for leaks around both connections.
12. Confirm Total Victory. Boil another kettle and pour it down the drain slowly. The drain should now flow freely, even if it was backed up before. If it still drains slowly after P-trap cleaning, the clog is farther down the line and needs a professional snake service.