Sink Backs Up When Washer Drains

When the sink backs up when the washer drains, it can be a frustrating and messy problem. There are several potential causes for this issue, including a clogged drain, a faulty washer drain hose, or a problem with the sink's P-trap. Here are some steps you can take to troubleshoot and fix the problem:

1. Check for a Clogged Drain

The first step is to check for a clogged drain. Hair, soap scum, and other debris can accumulate in the drain over time, causing it to become blocked. To check for a clog, remove the drain cover and use a drain snake or auger to clear any debris. If the drain is clogged, you may need to call a plumber to have it professionally cleaned.

2. Inspect the Washer Drain Hose

The washer drain hose is a flexible hose that carries wastewater from the washer to the drain. Over time, the hose can become kinked, crushed, or damaged, which can restrict the flow of water and cause the sink to back up. To inspect the drain hose, disconnect it from the washer and check for any kinks or damage. If the hose is damaged, it will need to be replaced.

3. Check the Sink's P-Trap

The sink's P-trap is a U-shaped pipe that is located under the sink. The P-trap helps to prevent sewer gases from entering the home and also acts as a barrier to prevent clogs from backing up into the sink. To check the P-trap, remove the cleanout plug and inspect the inside of the trap for any debris or blockages. If the P-trap is clogged, you can use a drain snake or auger to clear the blockage.

4. Call a Plumber

If you have tried the above steps and the sink still backs up when the washer drains, you may need to call a plumber. A plumber can use specialized tools and equipment to diagnose and fix the problem. The plumber may need to snake the drain, replace the washer drain hose, or repair or replace the sink's P-trap.