Kitchen Sink Overflowing Due to Laundry Hookup – Plumbing Question 430

The upstairs apartment has a laundry hookup.  When the family does laundry, the water comes up in my kitchen sink on the first floor directly below and overflows onto my kitchen floor.  Even when we fill up the kitchen sink upstairs and let it all drain out at once, the water fills up in my kitchen sink, again, directly below.  The family that lived upstairs previously had a different washing machine and we never had the problem.  We had a plumber snake out the drain pipes, no clog, and the problem continues.  The plumber thinks it must be that the drain pipes are too narrow, but this does not explain why it didn’t happen before and why it should happen with lesser quantity of water draining from their kitchen sink than from the washing machine.  Can you please give your opinion as to what may be the cause and cure for this problem?  Thank you

Answer:

The family above your apartment unit new washing machine is likely working more efficiently in pumping out and draining the water, thus putting the drain pipe under more stress.  I do suspect that the plumber who snaked out the drain is correct about the inadequacy of plumbing drain pipe system that is installed.   The apartment ownership should take measures to properly correct this problem and given that potential for further water damage since this issue is ongoing, hopefully apartment management will take the necessary steps to permanently resolve the issue.