Hi Sheila
We used to have an Aquasource kit but found that the water pressure reduction was such that water only came out of the taps very slowly. We overcame this by using the alternative method which is to retain your water container (Aquaroll or similar) and put a small float valve into the side entry of the container and connect the Aquasource pipe directly to this having first removed the the caravan adapter 'plug' which is the pressure reducing valve. This method gives the usual pump pressure to your system but maintains a water container about 50% full at all times, just the same as the water tank in your house.
I know it is possible to buy a ready made bit of kit, I think made by the Aquasource manufacturer, but it is quite easy, and substantially cheaper, to make your own. You just need a spare Aquaroll cap (from caravan accessory shop), a small float valve, (the sort used in a toilet cistern), and a quick release hosepipe connector and the equivalent