Gushing grey water

[jonandshell]

Now you have a discharge pipe full of water which will freeze and prevent you emptying it!
Hymer use an inboard valve within the waste tank shroud for that very reason!

 

[DavidG58]

Now you have a discharge pipe full of water which will freeze and prevent you emptying it!
Hymer use an inboard valve within the waste tank shroud for that very reason!

Accepted, but this way cost me under £20 and I could do it myself, the valve is still in place on the tank outlet and could be changed if a new owner wanted, but the cost and difficulty is much higher

I don't climb mountains in winter in mine

But it did freeze in Durness, so when it thawed I left it open and used a bucket

edit - and it was only a link for the OP, he already has an external valve anyway