How can I accommodate high washing machine drain flow rates with older plumbing?
As mentioned in other posts, in the old days, we had laundry sinks/tubs that the washer drained into. The tub would fill up and then slowly drain. The tub acted as a &quot;buffer&quot; to temporarily hold water until the drain would catch up. My solution was to replace the 1 1/2&quot; drain pipe with 3&quot; pipe. I used a 3 to 1 1/2&quot; reducing coupler to mate with the existing drain, connected 24&quot; or so of 3&quot; pipe, put another reducing coupler on top for the hose to go into. The top reducing coupler is just so nothing accidentally falls in. A 3&quot; pipe holds 4 times the amount of water that a 1 1/2&quot; pipe holds for the same length (a 4&quot; pipe holds 7x the water!). The 3&quot; pipe mimics the old laundry tubs. Newer HE washers use a lot less water so we don't need big tubs. Here's a picture: