We have a small washing machine in our condo that we hook up to our sink. We've had it for the past 8 years with no issues. Recently, after about two years of no one living upstairs, some new people moved into the unit above ours, and the new neighbour has mentioned to me that sometimes they get water backing up into their kitchen sink (which is above mine). Could my laundry be causing this? He is very friendly, by the way -- he's just worried there's a problem coming from upstairs, and as his upstairs neighbor is an odd bird, his feeling is that the sink burbling must be being caused by something *she* has done, but I'm worried it could be me. Also sometimes lately the water level of our toilet has been very low.

Water cannot flow upstairs. It would overflow your toilet, tub and other openings before your neighbors. As far as low water in the toilet bowl,make sure the tank level is proper and the small tube from the fill valve is inside or at least flowing water onto the overflow tube. Since this is an apartment, have maintenance look at it.

No... how can water run uphill? For your washmachine to back up into their unit ABOVE you it would first have to defy the law of physics. What is wrong is they have a drain clog they need to deal with...

Smoothy. -talk about timing!

Smoothy. -talk about timing!

Actually I am assuming this isn't in Europe. But is in the US or Canada. I know in itally the washing machine drain has a threaded coupling into the wall... not the slip coupling we are more familiar with into a vertical drain pipe that has a P-trap... since that plumbing is hidden in masonary walls... and I haven't seen enough rough-in plumbing in Europe... there is a remote possibilitiy depending on how its actually run... But based on terminoligy used... I'm guessing this isn't the case for the poster.