My darkroom is what once was a small dressing area adjacent to a bathroom. It sounds like it has access to running water but it really doesn't. The bathroom is tiny and the shower stall is too small to use as a print washing area without removing the shower doors so put in a tray or washer. The good part about it is that it is "dark". Anyway, it's not really practical to use the bathroom for washing film or prints.
I've actually had very few darkrooms that had running water. I process my film at the kitchen sink and carry my prints in a holding tray to the kitchen for washing. Since my wife occasionally wants to use the kitchen for cooking, I have also just ordered a Versalab washer that I expect will speed up the process and get me out of her way a lot faster.
As long as there's water available somewhere in the area, you can always carry your prints and film to the water for washing. It's a lot easier than carrying the water to the prints and film and cheaper than plumbing work.