Washing machine anti syphon valve

[greencarman]

Can any one tell me if i need anti syfine units for both my dishwasher and washing machine or just washing machine when plumbing both waists into an airtight tap waist pipe.

 

[JohnD]

They should both be put loosely into standing pipes with traps (an alternative is to attach them to a sink trap but this is not as good).

 

[greencarman]

but do i need anti syphone valves on both appliance waists

 

[JohnD]

If you use the standing pipe arrangement, the waste hose fits in loosely and does not make an air-tight seal, so syphoning does not occur and you do not need an anti-syphon valve.