Kitchen sink clogged on both sides? Here is why
Quick answer
When both basins back up, the clog is past the point where the two drains join, usually in the shared trap arm or the branch line in the wall. Plunging one side pushes water into the other, which is the tell. Clearing it runs $99 to $250 in Charlotte. If other fixtures back up too, the problem is the main line, not the sink.
A double sink where both basins fill up is actually giving you useful information. It tells you roughly where the clog is, which decides whether you can clear it yourself or need a drain machine. Here is how to read it.
What both sides backing up means
Under a double sink, each basin has its own drain, and they meet at a tee before running through a shared trap and into the wall. If only one side backs up, the clog is upstream of that tee, usually in that basin's own drain or the disposal. If both sides back up, and plunging one pushes water up the other, the clog sits past the tee, in the shared trap arm or the branch line inside the wall. That is the common case, and grease is usually the culprit.
What to try yourself, in order
- Plug the second basin tightly with a wet rag, then plunge the first firmly. Without the plug, you are just moving water between basins.
- If you have a disposal, run it with cold water. Food packed in the chamber is a common cause. Our disposal guide covers a jammed unit.
- Put a bucket under the P-trap, unscrew the slip nuts by hand, and clean it out. This is the messiest but most effective home fix, and grease is usually what falls out.
- Skip chemical drain cleaners. They rarely cut a grease clog and they sit in the trap, so if a plumber opens it later, they open caustic liquid.
When to stop and call
If the trap is clean and it still backs up, the clog is in the branch line inside the wall, which needs a drain machine, not a plunger. That job runs $99 to $250 in Charlotte through our drain cleaning service. If a line clogs repeatedly, grease has coated the pipe and a snake only punches a hole through it. That is where hydro jetting earns its price by scouring the pipe wall clean.
The signal that changes everything
Watch what else is happening in the house. If the kitchen backs up and nothing else does, it is a kitchen branch problem. But if the sink backs up while the washer drains, or a toilet gurgles, or the lowest drains in the house flood first, the clog is in the main line, not the sink. That is a different and more urgent job. Our drain and sewer symptoms guide explains what multi-fixture backups mean.
Preventing the next one
Grease is the enemy, and hot water does not save you, it just moves the grease further down the pipe before it cools and hardens. Pour it into a can and bin it. Keep fibrous scraps, coffee grounds, and starchy foods like pasta and rice out of the disposal, since they swell and pack. Run cold water for ten seconds after grinding. These three habits prevent most of the kitchen clogs we clear in Charlotte.