The ever popular Whale pressure switch WU7207
This is has been and is still used by a large number of manufacturers and is a great addition to your van if you are always having trouble with your micro switch taps
Its initial design is to connect to a external pump system, when you enter the van you turn the power to your water system on and the pressure switch will tell the pump to run until all your pipe work is at pressure.
The Switch will then turn the pump off and when you open a tap it will sense a drop in pressure and turn the pump back on again
Designed for us with 12mm push fit pipe work but can be adapted to other pipes