Hello, I live in an apartment in the basement, and every time my upstaires neighbor does their laundry, when their washing machine drains, it overflows into my apartment through my drain pipe, but when I do my laundry it does not do that, I was wondering if there is anything I could do to stop that or will I need a plumber to come in? And why does this happen?? Thanks for any help you can give,
Sincerely
Melissa