Why would my washing machine fill up after i have done a full wash and the water has drained out of the system

the water going into the washing machine is stagnant water. renovation has taken place in my building with two flat conversions. there have been recent plumbing problems with water leaking into the flat below me. i cant understand why water would get into my machine if the wash has drained out.it seems to happen over a period and i would notice it the next day.Why would my washing machine fill up after i have done a full wash and the water has drained out of the system
Is possible you have a back flow, or vacuum problem with the drain system. Contact building maintenance and have your problem investigated.Why would my washing machine fill up after i have done a full wash and the water has drained out of the system
It can be a plumbing problem or it can be the timing chain on your washer needs to be repaired.