dark sludge water from the washing machine

our washing machine drains into our slop sink downstairs. the water is sludgy and smells. what should we be looking at for a remedy? is it the washing machine, pipes, other?

thanks!

Does it drain into a connection immediately near and after the p-trap under the sink? -If so, it is probably just temporarily pushing up the (stinky) water that normally sits in the trap. -In other words, not really a problem.

steel said:

Does it drain into a connection immediately near and after the p-trap under the sink? -If so, it is probably just temporarily pushing up the (stinky) water that normally sits in the trap. -In other words, not really a problem.

steel, i see what you mean. 

the hose from the washing machine dumps into the sink and then when the sink fills up it brings the water from the trap. also the sink is close to the main drain of the house. could it be that it is also bringing up water from there? how else could this be dealt with? do we need to "root" out or do something to the trap, drain to the main line or main line itself? does this happen to everyone? thank you

Sounds like a drain issue.  I've used Python Drain when the line from my clothes washer began to back up.  Local, friendly, affordable, MOL advertiser.  http://www.pythondraincleaning.com/

Don't get this. The water coming from your washing machine is either dirty wash water or cleaner rinse water. Maybe your machine is gunked up. This can happen if you do a lot of cold washes and seldom use bleach. Mold can grow on the inner drum of the machine and requires taking it apart to clean.

I'd say there is nothing wrong with your washer.

There is probably nothing that you really need to do immediately.

If you have a newer slop sink then I'm guessing that the trap is PVC but that it still connects to a length of the old galvanized leading into the main? If the sink is old then the trap is probably also galvanized? 

The solution at some point would probably be to have any galvanized replaced. -After decades of use those pipes can reduce down to the size of a nickel inside due to mineral build-up.

yes our pipes are old. the sink is new with PVC running to a pipe which feeds the main pipe. we had a section of pipe from the kitchen replaced a few years ago and the amount of residue which closed up the pipe was unbelievable! 

the pipes are painted over and look rusty. i should just as well attribute the issue here to them being galvanized from what you are saying, otherwise is there a way to tell if they are or not? though not sure what confirming if they are or aren't galvanized is going to do for me.

thanks for listening and the advice.

In our house in Maplewood, we had a lot of lint coming out of the washer drain. It would collect in the slop sink and smell because it was basically a wad of cloth holding moisture for a while. See if this is what's happening, because it's the least drastic thing.