[JRTJH]

If you look at your photo of the shower drain, there's the shower pan, the drain and a black rubber gasket between the two. On most RV shower pans, the weight of an adult will push down on the shower pan causing it to flex. If there's any looseness between the drain and the shower pan, that flexing will allow the water to leak. You can run the shower all day and it'll never leak, stand in the shower, 2 minutes later, there's water on the floor.

How to fix it? Some (not all) shower pans have an access panel that you can remove from inside the bathroom. If you're lucky, you can work from above the floor. On the other hand, if your luck is like mine, you're going to need to "shinney under the floor" in the basement, once you finally get in there, you'll see a hole about 6" in diameter with the shower drain, HEPVO valve and the lower part of the shower drain fitting. You can remove the HEPVO valve (PAY ATTENTION TO HOW IT'S ORIENTED BECAUSE IT WON'T DRAIN IF YOU INTALL IT UPSIDE DOWN). Once the valve is removed, you can remove the drain fitting, clean it up, have someone in the bathroom clean up the top part of the drain fitting, reinstall it with some sealant on the black rubber gasket and then reassemble it (with the HEPVO valve properly positioned), let it dry overnight and hopefully you'll be "good to go".....