The Attwood 6144 dual action pump is a hand pump and a faucet all in one.  It works when hooked up to a campground or not.

When there is no water pressure to the faucet, just pump by hand to bring water to the sink.  When lines are pressurized, the faucet works as a simply valve turning water on or off.  Great for trailers without 12V DC power.

1/2" MPT supply fitting.