How can I stop my washing machine drain from overflowing?

Question

When my washing machine drains it sometimes comes up and out of the open pvc pipe in the service closet where the water heater would drain. I've found lots of posts where people speak of the washer standpipe overflowing, but can't find any info on what would cause my problem. When the washer drains I have to stand at the service closet (next to each other in the garage) and watch/listen. First I can hear gurgling, then hear the water coming up the pipe (similar to the sound of filling a glass of water), then I can see the water just before it emerges and floods my service closet and garage. If I turn the washer off and on as it drains this doesn't happen...but not really feasible for the long run. Any ideas?

Answer 1

It sounds like the pipe is partially blocked and water can only get through at a slower speed. The drain at the hot water is the lowest point so that's why it is coming from there. The blockage could be anything, from debris that came in through the pipe in the service closet or a sock that made it out of the washer. Since it's after where the water is coming out of the service closet then you might be able to get a drain snake the problem but you might have to get an expert to get it cleaned out.

Answer 2

lqlarry is likely right, and using a snake to clean out the line is the first step. (+1 Larry)

It could also be a problem with the plumbing vent. If that is the issue, you would likely hear a gurgle after you shutoff the washing machine and the water gets down to the P-trap, not unlike the sound the toilet makes at the end of the flush.

The other issue I can think of is that the plumbing drain is improperly sized or sloped. If that's the case, this problem would have always happened, and wouldn't be a new issue.

Answer 3

Think air behind water. The drain must be properly vented for it to withstand the rush of water from a washing machine pump.