Both basins hold water
Water rises in both bowls and drains very slowly or not at all.
Start here: Start with the sink opening, then check the P-trap and branch drain.
Kitchen Sink Drain Problem
Kitchen Sink Not Draining
Direct answer: A kitchen sink that will not drain is usually clogged at the basket strainer, garbage disposal opening, P-trap, or the branch drain in the wall. Start by separating whether one basin or both basins are affected, and whether a garbage disposal is involved.
Most likely: The most common causes are food sludge at the drain opening, grease buildup in the P-trap, or a clog just past the trap arm.
Most kitchen sink drain problems can be narrowed down in a few minutes with a bucket, a flashlight, and a careful look at how the water backs up. If you find the blockage in the sink opening, disposal, or P-trap, this is often a manageable DIY fix. If the clog is deeper in the branch line or multiple fixtures are backing up, stop and hand it off before you create a leak or push the blockage farther in.
Don’t start with: Do not start with harsh drain chemicals, random part buying, or taking apart the wall drain. Those moves often make cleanup worse and do not help if the blockage is at the sink opening or disposal.
If one basin drains but the other backs up,check the baffle tee and disposal side before assuming the wall drain is clogged.
If both basins fill and drain slowly together,focus on the P-trap and branch drain after the sink opening is clear.
Last reviewed: 2026-03-31
Start by matching the way the sink is backing up
One basin backs up into the other
Running water on one side makes water appear in the other basin.
Start here: Look for a clog at the garbage disposal opening, baffle tee, or just below the sink.
Garbage disposal hums or is silent and the sink will not drain
The disposal side fills with water and may not grind or may only hum.
Start here: Treat the disposal as a separate branch first before opening the drain.
Sink was slow for days and now stopped
Drainage got worse over time, often after greasy dishes or heavy food scraps.
Start here: Expect buildup in the basket strainer, trap, or horizontal drain arm rather than a sudden broken part.
Most likely causes
1. Food sludge or grease at the basket strainer opening
This is common when water stands in the bowl but the blockage is right at the drain opening where scraps collect.
Quick check: Remove standing water as needed and look into the strainer with a flashlight for packed debris.
2. Garbage disposal blockage or jam
If the disposal side is the problem, water may back up into the other basin or the disposal may hum without draining.
Quick check: With power off, look for a jammed object and check whether the disposal resets and spins freely.
3. Kitchen sink P-trap clogged with grease or debris
A trap clog often causes both basins to drain poorly, especially after the sink has been slow for a while.
Quick check: Feel the trap under the sink. If it is full of standing water and the sink opening is clear, the clog may be in the trap.
4. Clog in the kitchen branch drain beyond the trap
If the trap is clear but water still will not move, the blockage is often in the wall drain or horizontal branch line.
Quick check: After removing and clearing the trap, briefly test drainage into a bucket. If flow still stalls, the clog is farther down the line.
Step-by-step fix
Step 1: Figure out which side of the sink is actually blocked
This tells you whether to start at the sink opening, the garbage disposal, or farther down the shared drain.
- Run a small amount of water into one basin at a time.
- Watch whether only one side fills, both sides fill, or water rises in the opposite basin.
- If you have a garbage disposal, note whether the backed-up side is the disposal side.
- Listen for gurgling from the other basin while water drains.
Next move: You have the failure pattern pinned down, so you can check the right area first. If the sink is already full and you cannot test safely, remove some water with a cup or small container and continue to the next step.
What to conclude: Shared backup usually points below the basin openings.
Stop if:
- Water is leaking into the cabinet while you test.
- The disposal is making a loud metal-on-metal noise.
- The sink is backing up fast enough to overflow.
Step 2: Clear the sink opening and any visible blockage first
A simple clog at the basket strainer or disposal opening is common and is the least invasive fix.
- Do not use chemical drain cleaner.
- Remove as much standing water as practical.
- Use a flashlight to inspect the basket strainer or disposal opening for food scraps, labels, grease sludge, or utensils.
- Pull out visible debris by hand or with tongs, not with your fingers inside a disposal.
- If there is no disposal, try a few short plunges with the other basin sealed on a double sink.
- If there is a disposal, do not plunge aggressively until you know the unit is not jammed or leaking.
Next move: If water starts moving normally, the clog was at the sink opening and you can flush with hot tap water for a minute. If the opening is clear but the sink still holds water, check the disposal branch next if you have one, or move to the trap.
What to conclude: A clear opening with standing water points lower in the drain path.
Step 3: If there is a garbage disposal, rule out a jam before opening the drain
A jammed disposal can act like a clog and can also back water into the other basin on a double sink.
- Turn off power to the disposal at the switch and unplug it if accessible.
- Press the disposal reset button if it has tripped.
- Use the proper bottom-turn feature if your unit has one, or carefully remove visible obstructions from the top only when power is off.
- Restore power and test with a small amount of cold water.
- If the disposal runs normally but the sink still does not drain, shut it back off and continue below the sink.
Next move: If the disposal spins and the sink drains, the problem was a jam or overload at the disposal. If the disposal hums, trips, leaks, or still will not pass water, stop using it and move to trap inspection or a disposal-specific repair page if leaking becomes the main issue.
Step 4: Open and clean the kitchen sink P-trap
This is the most common place for grease and food buildup once the sink opening is clear.
- Place a bucket and towels under the trap.
- Loosen the slip nuts by hand or with pliers if needed.
- Lower the trap carefully and empty it into the bucket.
- Clean out grease, sludge, and debris from the trap and the short tailpiece connection.
- Look into the horizontal trap arm toward the wall and remove any reachable buildup.
- Reassemble the trap squarely and hand-tighten first, then snug just enough to stop leaks.
Next move: If the sink drains freely after the trap is cleaned, the clog was in the trap or just at the trap arm entrance. If the trap was mostly clear or the sink still backs up right away, the clog is likely farther down the branch drain.
Step 5: Decide whether this is a deeper branch drain clog or a simple under-sink repair
Once the opening, disposal, and trap are ruled out, the next move should be deliberate so you do not create a leak or push the clog deeper.
- With the trap removed and a bucket in place, briefly run a small amount of water from the sink into the open drain path if practical.
- If flow from the wall connection is slow or backs up, stop and treat it as a branch drain clog.
- If the trap leaked because the washers are distorted, cracked, or missing, replace the kitchen sink P-trap or trap washers and retest.
- If the basket strainer body is loose, corroded, or leaking while you work, shift to a sink leak repair instead of chasing the drain problem further.
- If the clog is clearly beyond the wall and both basins are affected, use a hand auger only if you are comfortable doing it without forcing the cable. Otherwise call a plumber.
Repair guide: How to Replace a Kitchen Sink Basket Strainer
Related repair guide: How to Replace a Kitchen Sink P Trap
A good result: If a resealed or replaced trap stops leaking and the sink drains, finish with a full-basin test on both sides.
If not: If the wall drain still backs up or other nearby fixtures are slow too, hand this off as a branch drain clog.
What to conclude: Past-the-trap blockage is no longer a sink-only repair.
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FAQ
Why does water come up in the other side of my kitchen sink?
On a double-bowl sink, both basins usually share the same drain path. If one side backs up into the other, the clog is often at the garbage disposal opening, the baffle tee between bowls, the P-trap, or just beyond the trap.
Can I use boiling water to clear a kitchen sink clog?
Hot tap water is the safer first choice. Boiling water can soften or stress some plastic drain parts and may not help much with a heavy grease or food blockage. Clear visible debris first, then clean the trap if needed.
Should I use chemical drain cleaner in a kitchen sink?
It is better not to. Chemical cleaners can sit in the trap, splash when you open the drain, and damage finishes or seals. They also do not fix a jammed disposal or a trap packed with solid debris.
How do I know if the clog is past the P-trap?
If the sink opening is clear, the trap is cleaned out, and water still backs up quickly, the clog is likely beyond the trap in the branch drain. A backup from the wall connection with the trap removed is another strong sign.
When should I call a plumber for a kitchen sink that will not drain?
Call when multiple fixtures are slow, the wall drain backs up, the clog will not clear with basic under-sink work, or you cannot stop leaks after reassembling the trap. Those signs point to a deeper drain-line issue or a repair that needs better access.