Plumbing in Dishwasher

[Dgrw]

I have a question I would like to ask someone in the know.

I have recently bought a dishwasher and have the hot cold water supplies in place to accomodate the appliance. My question is, regarding the waste/ drainage. My dishwasher will be located directly next to the sink which of course has an existing trap and drainage pipe to the outside. Would I get away with buying a new trap for under the sink with a spigot attachment for the dishwasher waste/drainage or will I have to break through the wall at a lower level and connect the drainage up externally?

My fear is that during dishwasher operation the sink will fill up with the spigot arrangement. Is there any truth in this or will I get away with the spigot idea.

p.s my waste from the trap under the sink is pretty much 90 degree to the ground, externally.

Any help appreciated.

Dan

 

[Bahco]

Traps with spigots are nice and easy for the plumber to install but in practice you do get problems with flowback.
I installed one a few months ago and the client is complaining that sink water is flowing back into her washer.

I would add a standpipe trap and have a separate waste pipe to be on the safe side.

 

[chrishutt]

Disagree with Bahco The sink waste will not run back into washing machine if you loop the discharge hose upwards towards the sink top before connecting (for example if you have to cut a hole through end of kitchen unit for discharge hose, site this as high as you can to ensure drain-back (new word I just invented?) does not occur.

 

[Bahco]

Fair play Chris.

I'll take that on board.