Kitchen Sink Backing Up on Both Sides: Causes and Fixes

What are the 4 causes of a kitchen sink backing up on both sides?

The 4 causes of a kitchen sink backing up on both sides are listed below.

• Grease and food scraps build up in the shared trap.
• A clog forms in the branch line behind the wall.
• A garbage disposal jams and blocks one side.
• A main line clog backs water into the kitchen sink.

Is a kitchen sink backing up on both sides a main line problem?

No, a kitchen sink backing up on both sides is a branch line problem in most homes, and it becomes a main line problem when other drains back up too.

What should you do first when the kitchen sink backs up?

The 4 things you should do first when the kitchen sink backs up are listed below.

1. Stop running water and the dishwasher.
2. Run the garbage disposal once to clear its chamber.
3. Use a plunger with the other drain blocked.
4. Call a plumber when the water does not drain.

When should you call a plumber?

You should call a plumber in the 4 situations below.

• Plunging does not clear the clog.
• The dishwasher drains into the sink.
• Other drains back up too.
• The trap leaks under the sink.

Related plumbing problems and next steps

How much does the plumbing repair cost?

The plumbing repair cost depends on the clog: drain cleaning costs $147–$345 per drain, according to HomeAdvisor. Kitchen sink plumber prices and local plumbers are on the kitchen sink plumber in Lancaster page.

What is a related plumbing problem?

A related plumbing problem is gurgling drains in house, and the gurgling drains in house guide lists its causes and first steps.

Written and fact-checked by the Lancaster PA Plumbers editorial team using HomeAdvisor, EPA WaterSense and City of Lancaster data. Last updated October 29, 2026.