Our Kimberley Kamper has 2 water tanks. The first 130 L main tank is plumbed in with a PAR-Max 2 diaphragm water pump. It works well and feeds the kitchen, diesel hot water system and shower outlet. It can pump at a rate of 11 L/m and can draw from an external source. The second water tank is 70 L and has only one output, a hand pump at the front of the trailer. This was useful as it was accessible without opening the kitchen and did not require power. However we were never huge fans, as it was hard to pump and fill any thing large in size. Recently the hand pump broke so I decided to replace it with an electric pump and new tap.
After some research I bought a Seaflow 21 Series DC Diaphragm Pump which was sourced on eBay. It's a pressure activated pump, capable of 3.8 L/M and draws less than 4.0 Amp in operation. I decided to locate it in the front gullwing near both the tap and 12 V power.
Power was wired into the existing kitchen pump power switch and circuit breaker. Both pumps draw less than 5 Amp so if both are operating simultaneously they will not trip the 10 Amp circuit breaker. It was easy to run a wire through the existing wiring loom. Water pipes were placed through the floor and connected to the existing source tank pipe and the new tap.
So far it's working extremely well; about as loud as the existing kitchen pump. I thought long and hard about putting in a water filter but in the end decided against it to keep the set up simple and because we only put good quality water in the tanks. It can be easily added later if we feel the need.
Total cost
Pump $55 (ebay)
Tap $60 (ebay)
Hose & fittings etc. $20