Slow Draining Sink
Updated February 20, 2026
Almost always a partial clog from hair, soap scum, grease, or food debris in the drain, P-trap, or branch line. Simple DIY fix, under 30 minutes.
Overview
Left untreated, partial clog becomes full blockage -- standing water, odors, potential leaks. Good news: vast majority cleared without a plumber and without chemical cleaners. Depends on where the clog is: stopper, P-trap, or branch line. This guide works from simplest to deepest.
Symptoms
- Water pools and takes noticeably longer to drain
- Gurgling or bubbling -- trapped air behind a partial clog
- Unpleasant odor from trapped organic matter decomposing
- Water backs up when running the dishwasher or disposal (kitchen)
- Have to wait for the basin to empty before continuing
Common Causes
- Hair and soap scum -- number one cause in bathrooms. Hair wraps around the stopper, accumulates soap residue, creates a dense mat.
- Grease -- liquid when hot, solidifies in the pipe. Gradually narrows the passage and traps food particles.
- Food debris -- coffee grounds, rice, pasta, fibrous vegetables accumulate at bends in the line.
- Mineral scale -- hard water deposits gradually reduce pipe diameter. Slower process but compounds other clogs.
- Deeper blockage or vent issue -- past the P-trap in the branch line, or blocked vent preventing proper airflow.
What You'll Need
How to Fix It
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Clean the Stopper or Strainer
Bathroom: pull the pop-up stopper straight up or twist and lift. Hair and soap scum wrapped around the rod -- clean it off. Kitchen: remove the strainer basket, clean out food debris. This alone solves it in many cases.
Tip: Zip-it tool ($3, hardware store) pushed through the drain pulls out hair without removing the stopper. Keep one under every bathroom sink. -
Try the Baking Soda and Vinegar Method
Remove standing water. Half cup baking soda, half cup vinegar. Fizzing breaks up soap scum and light grease. Cover with a wet cloth to keep the reaction in the pipe. Wait 15-30 minutes, flush with boiling water.
Warning: PVC pipes (white plastic)? No boiling water -- softens and warps joints. Very hot tap water instead. Boiling is safe for metal and ABS (black plastic). -
Plunge the Drain
Cup-style plunger (not flange/toilet). 2-3 inches of water for a seal. Double basin? Plug the other drain. Bathroom? Wet rag in the overflow hole. Plunger over the drain, pump 15-20 times, sharp pull on the last stroke. Water rushes down? Cleared.
Tip: Petroleum jelly on the plunger rim for a better seal on smooth porcelain. -
Remove and Clean the P-Trap
Bucket under the P-trap. Unscrew slip-joint nuts by hand or channel-locks (tape on jaws to protect chrome). Pull trap down, dump contents. Clean inside with a bottle brush. Inspect the wall pipe for visible blockage. Reassemble, hand-tighten, test.
Warning: P-trap water may be foul-smelling. Towels ready, ventilated area. -
Snake the Branch Drain Line
P-trap clean, still slow? Blockage deeper in the branch line. P-trap removed, feed a hand-crank snake into the wall pipe. Clockwise as you feed. Resistance = clog. Keep cranking to break through, pull back slowly. Run water with P-trap off to confirm flow, then reassemble.
Tip: 25-foot hand-crank snake: $20-30, handles most household clogs. Beyond 25 feet or cannot break through? Plumber with a power auger. -
Flush and Test
Reassemble, run hot water 2-3 minutes. Fill the sink completely, release the stopper. Should drain quickly with no gurgling. Still slow after all steps? Blocked vent or main line clog -- plumber territory.
When to Call a Pro
Call a plumber if it persists after stopper, P-trap, and snake, if multiple drains are slow simultaneously (main line), if other fixtures gurgle (vent problem), if the wall pipe is corroded and will not take a snake, or if you prefer not to disassemble. Camera inspection pinpoints deep clogs.
Prevention Tips
- Mesh drain screens in every sink. Catches hair and food before it enters. Under $5 each.
- Hot water 15-30 seconds after each use. Flushes grease and soap through.
- Clean the P-trap every 6-12 months even if the drain seems fine.
- Never pour grease down the drain. Paper towel first, grease in the trash.
- Monthly baking soda and hot water flush down each drain.
- No chemical drain cleaners. Temporary relief but corrodes pipes over time.