Scott,
There should always be a one-way valve between the dishwasher pump and the disposer connection (dishwashers usually empty directly into the disposal).
I have often read - and certainly my experience confirmed it - that the angle of the waste pipe from the disposal is crucial. If there is any bend or rise, waste will gather there with 100% certainty.
When I replaced my folk's 50+ year old unit last summer, I had the drains reamed out. It is unbelievable how much faster the water now drains. Obviously, here to there is a real danger of blockage from the disposall if the plumbing system is dirty or slightly clogged - or poorly laid in.
You can get the one-way valve at any marine or camping store in case your appliance dealer looks at you like you are crazy, make sure to get one rated for hot water. Bet your plumber used one and that is why the problem is solved.
There should always be a one-way valve between the dishwasher pump and the disposer connection (dishwashers usually empty directly into the disposal).
I have often read - and certainly my experience confirmed it - that the angle of the waste pipe from the disposal is crucial. If there is any bend or rise, waste will gather there with 100% certainty.
When I replaced my folk's 50+ year old unit last summer, I had the drains reamed out. It is unbelievable how much faster the water now drains. Obviously, here to there is a real danger of blockage from the disposall if the plumbing system is dirty or slightly clogged - or poorly laid in.
You can get the one-way valve at any marine or camping store in case your appliance dealer looks at you like you are crazy, make sure to get one rated for hot water. Bet your plumber used one and that is why the problem is solved.