A washing machine drain usually backs up into a nearby sink because the two share a drain line that is partly clogged. When the washer pumps out a large amount of water quickly, the clogged pipe cannot carry it away fast enough, so the water rises out of the lowest opening, often the sink.
Why Washers Cause Backups
Washing machines release many gallons of water in a short burst. A drain line that handles a sink just fine may not keep up with that flow if it is narrowed by buildup. Lint, soap residue, hair, and bits of fabric collect in the pipe over time. In some homes, kitchen grease travels into the same line and makes the clog worse.
Common Setups That Lead to Trouble
- A laundry sink and washer that share one drain
- A kitchen sink connected to the same line as the laundry
- An undersized standpipe or drain line
- A drain without a lint trap on the washer hose
Signs the Problem Is Getting Worse
At first, water may rise a little in the sink and then go down. Later, it may overflow, gurgle loudly, or leave dirty water standing for a long time. If a basement floor drain also fills up when the washer runs, the clog may be in the main line, not just the laundry drain.
Easing the Load on the Drain
Add a mesh lint trap to the end of the washer drain hose and clean it often. Run smaller loads if the backup is mild. Avoid pouring chemical cleaners into the laundry sink, since they rarely clear lint clogs and can harm pipes. If the sink overflows, stop the washer and wait before starting another load.
Keep track of how often it happens and whether it is getting worse.
When the shared line keeps backing up, clearing the laundry drain line can restore full flow. If other drains are slow too, you can ask a plumber to check the main line at (833) 603-1840.