My lower element went out, and I figured for $30 or so, might as well see if I could stretch it out a few years. Hooked up hose, ran hose to drain, and opened up outlet. Didn't pay any attention and thought it drained. When I removed element, water started pouring out. Ended up pulling element out slightly, vacuuming until shop vac was full, replacing element to dump vac, and repeating 8-10 times.
So much sediment (rural water) in there that the outlet drain plugged immediately, but I never noticed. I did stretch the life of the water heater about another 4 years with the new element, though.