It sounds like I'm having the same problem as the person above. But my washing machine is full of nasty, greasy water from, I'm assuming, my kitchen sinks. We have a garbage disposal and a double kitchen sink. The laundry area is outside in a room off the carport. We are hooked into city sewer.

Last night I noticed the kitchen sinks were not draining... so, I used a plunger and the sinks started draining as usual. BUT, this morning when I went out to start a load of clothes, the washing machine is FULL (large capacity size) of nasty, greasy, water. The same water I plunged from my kitchen sink. I started the washer at the beginning of the rinse cycle and it immediately backed up into the kitchen sinks. :eek:

Would calling a company such as Roto Rooter be wise or do they mainly have knowledge of just sewer lines? Is there something I could do before I call and pay for a service call? And what can be done to prevent this again in the future?

Any and all answers are greatly appreciated! :)

You obviously have a blockage between the kitchen sink and the main drain line or between the washer stand pipe and the main drain line which ever is closer to the main line. Also you must have a sealed connection between the washer drain hose and the washer stand pipe. Remove the washer hose and seal the pipe with duct tape. Fill the kitchen sink about 1", then try plunging. That might clear the blockage. If not, you will have to have someone snake the line to clear the blockage. Just about any plumbing company can do that for you.

Sounds like the clog's located downstream from the kitchen sink. The solution would be to snake the drain line from the kitchen roof vent. Did you wish to try this yourself?
You ask,
And what can be done to prevent this again in the future?
As long as you are putting fiber, grease and garbage into the same branch expect clogs and backups. Snaking the branch on a regular maintenance schedule is about the thing you can do. Good luck, Tom

While you were plunging you sink were you running the disposal? If so this is how the water got out of the sink into the washing machine. And this is caused by the connection between the washer hose and the stand pipe for the washer drain is sealed like HKSTROUD said above. If you leave the hose just hanging into the pipe the next time the sink stops up it will not back up into the washer.