S
SafeT
The property is on a 3rd floor and there is the dishwasher and sink down the same waste pipe.
There is also an anti syphon which lets air int he system.
Worked well over last 4 years suddenly the sink drainage starts to fill the dishwasher and then the dishwasher sometimes starts to fill the sink.
When I press the air valve (small black plastic needle) water comes out and it drains perfectly for a while.
The drainage seems to work fine for a few minutes and then the back up happens.
I replaced the anti syphon part and still no joy.
Help please!!
Ps. the drain is not blocked, it seems as though air bubble is created in the pipework??