When washing machine is done washing and starts to drain water from it... the water goes but will slowly build up in standpipe until it will flow over onto floor... if I run my garden hose down drain and standpipe it never backs up the pipe... I went to roof vent and run water down and water goes... only when washer is draining it slowly build s up in stand pie and will overflow onto floor... if I stand there and watch drain and stop washer before it runs out of standpipe.. the water goes and makes gulping noise 2 or 3 times and water is gone.. and I start it again to drain and water will build up... it seems like I have an air problem for water flow... or washing machine does not have enough force to push water through p-trap... any help please

Hi John...

Your issue is more of a VOLUME issue than a washing machine issue.

Here, the volume of water from a garden hose doesn't cause an issue, but when you discharge the great volume of water out of a washing machine hose and into the drain the pipe overflows because the drain is only PARTIALLY CLOGGED... ;)

Your best bet would be to cut into the drain pipe just where it connects into the largest drain pipe and open the drain pipe wide open at this junction. Here, most of the time, there are dissimilar metals at the junction between the washer drain and the waste stack that create an electrolytic effect that makes it so minerals deposit on the inside of the pipe and slowly clog the drain at this junction.

Basically, you can try to snake the drain... may work, but most likely, if you can access the junction mentioned above, you will be best to cut out a section of pipe and clear the partial blockage to restore the drain to full size.

Questions? Let me know, OK?

Mark