What Happens When You Drop This in Your Freshwater Tank ?

It will not cause a problem, Just leave it be.. IF you are evern in a position to fish it out, go ahead but frankly, not worth much effort.

In fact... On my coach the Ten-Ts who designed it (1 Dee, 10 T) or 1 d 10 t) put the drain holes like 1.5" above the floor, so I put in a different plug (A valve) and mounted a short siphon hose on the inside end of the vlave, made of teh very same hose as you dropped in the tank, just a size smaller.