bcarroll wrote:
To put your mind at ease(hopefully), I disconnect the dump hose and hold it under the dump valve. The sprayer I use is a hand held attachment where you squeeze the handle and it squirts a stream of water up into the dump valve pipe/tank - I do not put the hose up the dump valve pipe. Rinsing the dump tank is the only purpose for that.
All the water etc. drains into the stinky slinky - none on the ground.
There is actually some attachment that you can buy to make that process easier and cleaner. The brand name that I know is the Flush King. Its a 45 degree attachment that you put between your trailer valve and your sewer hose. There is a fitting for a garden hose that squirts water back into the black tank. The water than drains back into the fitting and down the pipe. No splashback or dripping on the ground.