What size drain pipe do you need for a wash machine?
The discharge line on non commercial washing machines is universal at 1" ID and inserts into a 1-1/2" riser that ties into the residential waste water drainage system.
1 1/2 inch is fine.
1-2 inches. Sometimes it depends on the washing machine
Typically it's a 2" pipe.
In Canada Plumbing code is an 1 1/2" with a P trap connected before the main stack of your house