On Tuesday, June 24, 2014 11:44:01 AM UTC-4, Tom wrote:
I have a single sink with attached garbage disposal. the dishwasher is

connected directly and it all works correctly and there is no drainage

problems. I do how ever have backup from my laundry room washer some

twenty feet away.



Do I need to add something to the trap or in-line with the plumbing.



Thanks



--

If what you're saying is the washer is backing up into
the kitchen sink, then you have an obstruction in the line
further down from both the washer and the kitchen sink.
The washer puts enough volume in there, it can't get
through, so it backs up. That is the most likely source
of the problem.

What happens if you fill the sink with water and let it
all go at once? Drains slower than it should?