I am house sitting and a brand new washer and dryer were installed. When the washing machine goes into spin cycle after a rinse cycle, there is water that comes back up through the kitchen sink. Even when the old washer was in place the back up of water in the kitchen sink still happened. Is it the septic tank, drain field because of melting of snow ? Septic needs pumping ? This is the only place that water comes up in. It doesn't come up through bathroom tubs and sinks.

Washers drain fast. There is a partial clog along the drain. The kitchen sink in this house is next in line? Get some liquid drain cleaner that is safe for PVC and try it in the sink.

And buy a $2 'sock' that goes over the drain hose to trap lint, even though the clog could be lint, food, hair from bathrooms, anything.

Where is the clothes washer relative to the kitchen sink? There is a partial blockage in the drain line that serves them both. The clothes washer is pumping out more water than can drain past the partial blockage. Snake the drain line, probably from under the kitchen sink.

Joy, I thought you had been around the plumbing forum long enough to know better than to suggest chemicals for clearing this type of clog. I guess I was wrong. I, as a plumber, have been burned to many times with people using this crap and not letting me know. Lets get the facts straight, if the clog is further down than the trap of the fixture (and even when at or before the trap, not a good idea), chems will do no good for anything, or anyone.

Rox, the only real fix here is to auger the drain from either the kithchen sink or washer drain, whichever is further downstream, or has an easily accessible cleanout. The house sewer or septic tank is not the issue because if it were you would have backups in showers, toilets, floordrains, etc. Now, all that being said, just because you are house sitting does not make you responsible to take care of this yourself, or at least it shouldn't. Contact the homeowner, explain the situation, and ask them what plumbing company they would like you to call to get this problem resolved, or better yet, have them call the company first hand to get things taken care of. Your job as house sitter would only be to make sure you are there to let the plumber in when they get there. Simple.

Yes, I should have known better.