The tds readings are high! DI only not a remotely good idea with readings like that
If you are relying on just the tap pressure of mains water it is hardly surprising you are going through so much water.
With a proper system to suit your needs, whether it is a trolley/backpack/van mount or trailer system it is unlikely you'll use anything like that amount of water.
No one system is the best, it depends on the depth of your pocket for one thing, and your own particular type of round, your vehicle and the type of house you live in. (1st floor flat, water meter, size of or lack of garden etc.)
Ask as many specific questions on here as you can, check out the back pages too, there isn't a question you might have that hasn't already been answered somewhere on here!
But easier to ask a few direct questions and build up your knowledge base that way, searching out back posts is a pain!
But try and think carefully about your questions, and don't put too many in a single post either! Otherwise half of them won't get properly answered
Ian