as a plumber, having trouble with customer, dishwasher making extremely large quantity of soap suds which backs up thru the plumbing system, which of course since we changed some main pipe we are blamed, on renovation work pipe was increased to 2 inch and run 50 feet to 4 inch stack, one basin still on this run in the wall of bathroom floor above sewer main and one below washroom. Soap backs into the sink, and this part was not touched, as existing in wall 1 1/2 inch 20 feet straight down, sink about 5 feet below the base, any comments why so much soap, Thanks