I'm trying to create a standpipe for my laundry tubs drains to prevent water back up after heavy rains, but I'm having trouble getting PVC fittings to work.
The inside-the-tub threads are slighty to small for a 1 1/4 in MIPS adapter and too wide for a 1 inch adaptor. Any suggestions as to how I can get this to work.? A check valve in the tub drain line and a back-water valve are down the road, permanent fixes .
Thanks Ken B