yeah, i just found that out i think davids3511 gave me an idea of building my own system. I dont konw anything about how the system works yet or what parts i need but i have a couple of months to learn
It's easy mate. Get yourself a tds meter and test your water. Anything over 50/60 you will need an ro to filter your water. That means you will need to connect it to your mains and have a holding tank if possible.
Under 50/60 and you can DI only which means you can fill your van tank with tap water and filter on demand as it were. I know there are variations but that is the general gist.
After that you need a tank (as big as your payload will allow), flow contoller (varistream and loads more), pump, 100m micro/mini bore hose, di vessel, hose reel, brush and pole. Get that and you have the basics.