Kitchen Sink Waste Flowing Back to Washing Machine Drainage and wastage systems and plumbing help, advice and answers

[jase46]

Hello.

My father in law has just moved into a new place, and noticed his washing machine was filling up with water. I guessed it was coming back in from the waste pipe so fitted an angled connection to stop the sink water finding its way up and in so to speak. Anyways hes getting a new washing machine so i unplugged it all but water is coming out of the washing machine waste connector put on there. Heres a pic of the set up. It looks like the trap is level with the waste so every-time he empties the sink some of the water goes into the washing machine waste. Was looking what to do maybe extend the trap lower so the waster is higher?.

[mrdrains]

It's the situation when your drainage is blocked and there is water in drainage pipe. When washing machine is sending the water to the drainage pipe, your pipe is already full of water and with the pressure of kitchen pipe it throws back to washing machine.

[jase46]

Ive removed the trap and its clear. The water runs ok out of the sink. The thing i noticed is the trap is level with the washing machine waste. Seeing the trap is always full of water and level with the waste it makes sense to me that some water is being pushed into the washing machine waste....sound or ?.

Im thinking lowering the trap so the washing machine waste is higher than the level could be a solution?.