Interesting that they fit imperial valves on the continent
We only have plastic valves on ours but mounted inside, except the grey waste which a stupidly designed gate valve activated by a long cable that was very reluctant to close and impossible to change cable without major dismantling underneath
I do wish more thought was given to how things would be changed as and when needed
Ditto! A tap at the end of the grey water pipe would fix he problem, bug further reduce the ground clearance. I carry a grey water container to put underneath.