My landlord ran the drainpipe for the washer to the pipe that also drains my kitchen sink, when the washer drains the dirty waste water it backs up into my kitchen sink. Is that in violation of Washington state plumbing code and or health codes?

Hi! JessieLee, welcome to AMHD :)

Is this a dish or clothes washer?

Not sure in your particular situation (because of local code), but dishwasher's are allow to drain into sink drains as long as they have the proper venting.

You may have something like this on the top of your sink:
http://t3.gstatic.com/images?q=tbn:Y4FXijAYMrg3qM:http://activerain.com/image_store/uploads/1/7/2/3/1/ar123440869213271.jpg

If it is a clothes washer, I agree it can be disconcerting to see "gray water" backing up into your kitchen sink, and there maybe a health concern depending on what type of dirt you are washing off your clothes.

In both cases the back-up is caused by either improper sizing of the drains or improper venting or both.

If I were you, I'd visit your local government entity's code's office, and make your inquiry.
They may also have the codes listed on their website, mine does.

K

My landlord ran the drainpipe for the washer to the pipe that also drains my kitchen sinkAnswer Kuxjs question. What washer are we talking about? Dish or clothes? Back to you, Tom