When our washing machine is draining, occasionally, the shower drain will backflow slightly. The washer is located in the garage next to our bathroom, which is 8" higher than the garage floor, but both washer and shower share the same 2" drain pipe. Can anyone suggest where I might be able to find a shower drain plug that would help prevent backflow in the shower drain? Any advice would be appreciated. Thank you.

Plugging your shower will not really solve anything. Water overflow inside your shower indicates that you have clogged drain. Clean the drain.

It's clean; it's actually a new drain; had no other option but to connect to same line.

What size is it ? How did you connect to it ?

It's a new 2" PVC drain connected to an exsisting 4" drain. The shower drain is between the washer and existing drain, approximately 3ft from the washer. The shower has approximately 2-3 ft of drain before it merges with the 2" Y from the washer. The washer has it's own vent next to it, and the shower uses the existing stack next to it.

If it is as you just described, so the sizing is fine. I am assuming you used all correct sweeps and other fittings to guide water down the drain.

What's happening is that your drains cannot absorb volume of water discharge from your washer. As a result, water column raises and shows at the first possible opening - your shower. This is usually caused by undersized pipe or partially blocked drain.

It appears that you may have a blockage - either - somewhere in the 2" pipe before it hits 4" pipe. Snake it out first. If you still get back-ups than you have clog in your 4" pipe.

Your shower is 1st in line to show sewage back ups. Snake 4" pipe.

. Can anyone suggest where I might be able to find a shower drain plug that would help prevent backflow in the shower drain? Any advice would be appreciated. Thank you.
Hey Ralph,
Check out the FloodGuard, (see image).

The shower drain is between the washer and existing drain, approximately 3ft from the washer. The shower has approximately 2-3 ft of drain before it merges with the 2" Y from the washer. The washer has it's own vent next to it, and the shower uses the existing stack next to it.
Not too good a idea to tie a shower next to a washer. Perhaps the FloodGuards will help. Good luck, Tom