Have aquired a 12v battery & a 80psi pump. Have connected them up so pump runs. Fitted a hose on & put it a 25L drum & put a hose on the outlet of pump & hey presto it pumps out water from the drum. Thought this will be handy for a spare if one of my backpacks packs up. My problem is turning it off. I'm useless with wiring so can anybody recommend a switch to turn it on & off & how do you fit it. It needs only to be simple as its only a spare & hopefully won't be used much.