My floor drain the basement backs up after a hard rain when I use my washer. The landlord contacted a plumber who said there is no connection between the two and that the backup is caused from grease in the kitchen sink upstairs. I don't put grease down the drain and the drain downstairs only backs up when it hards hard for a long time.

Is the plumber correct or can there be another problem?

Every time there is a hard rain, the basement drain backs up when I use the washer. The landlord insists that there is no connection between the two. He said he asked a plumber who said the problem is because grease is put in the kitchen drain upstairs.

I throw grease away in the trash. The downstairs drain does not back up unless it rains very hard for a rather long time.

Any thoughts?

Is the plumber correct or can there be another problem?
City Sewer or septic tank? Is the rain water routed into the sewer? Sounds like a heavy rain coupled with the washer discharge overloaded the system causing a backup. I don't believe, for a minute, grease from the sink caused this. Regards, tom

If septic, your drain field may be getting saturated. If city, you should not be affected by the rain(unless your storm and sewer are tied together(you don't see this hardly at all anymore). Either way, if it is only your washer causing the backup, your plumber is most likely correct. If you had a problem outside of the house, all fixtures would cause the floordrain to back up.

Try this. Fill your washer. Once it is completely full, switch it to spin(drain) and immediately flush any and all toilets in the house while the washer is draining. See if your floordrain backs up. If not, its most likey that your ks,washer,floordrain pipe was the problem, and the hard rain was just a coincedence.