Andew44 ask your questions to someone like Alex Gardiner or several other suppliers tell them the kind of work you have, how much you want to spend, they will then ask you a few simple questions like what is your tds? How much water pressure you have etc. Alex will even send you a tds meter and a pressure guage and advise you on what you really need for your kind of work and capacity. You don't need to produce thousands of litres of water for a small domestic round. No on uses a thousand litres a day on their own.