a long flexible pipe is connected to trap directly under sink oposite tee suplying dishwasher drain. water runs back into washing machine after completion with door open some time after and runs over floor is a non return fitted to unit what is possible cause

ernest williams, July 2009

The water is syphoning back into your washing machine, due to your outlet being sealed with no air vent. To prevent this, you need to make sure that the pipe from the washing machine fits loosely into a draining pipe so that the end of the outlet pipe isn't in contact with the water, this prevents the water syphoning back down to the lowest level, ie, your washing machine. I suggest that you put in a seperate pipe and P trap for your washing machine. The pipe needs to be about 2ft above the floor level with the P trap at the bottom.

Bri, July 2009