I have a two family house, daughter upstairs washing machine is backing up into my tub and my bathroom sink... snaked the bathtub it didn't help, water is dirty. Thank you.

Snaking for a clog is good but don't snake at the tub, clog isn't there. The tub is the low spot in your system so when your main drian clogs it backs up there. Is there a basement and maybe a clean out on a 4" drain line? If so, don't open it just tell me about it

There is a basement with bathroom, no trouble in that one, toilet is run off a sump pump... closet full of many many pipes... don't know which is which. Strange... water going down in tub but backs up when daughters washing machine is draining. Always had a slight back up when she did her wash, but now her water from machine fills up my tub and for the first time now backing up into my bathroom sink... water is dirty, seems like almost dirt. Could it be my roof vent... thanks so much for trying to help me. Was just laid off from job due to economy, so hard to afford a plumber.

There is a basement with bathroom, no trouble in that one, toilet is run off a sump pump... closet full of many many pipes... don't know which is which. Strange... water going down in tub but backs up when daughters washing machine is draining. Always had a slight back up when she did her wash, but now her water from machine fills up my whole tub and for the first time now backing up into my bathroom sink... water is dirty, seems like almost dirt. Could it be my roof vent... thanks so much for trying to help me. Was just laid off from job due to economy, so hard to afford a plumber.

There is a basement with bathroom, no trouble in that one, toilet is run off a sump pump... closet full of many many pipes... don't know which is which. Strange... water going down in tub but backs up when daughters washing machine is draining. Always had a slight back up when she did her wash, but now her water from machine fills up my tub and for the first time now backing up into my bathroom sink... water is dirty, seems like almost dirt. Could it be my roof vent... thanks so much for trying to help me. Was just laid off from job due to economy, so hard to afford a plumber.

Toilet is run off a sump pump tells me your sewer line leaves the house above the basement floor, this is call an ejector pump which lifts the sewage up to the first floor. This is why the basement bath still works, it really is not part of the main drain. Go up to where the ejector is connected to the main, there should be a clean out there. Again don't open it just come back once you locate a clean out.