Just deleted my original post as I got the pure to waste the wrong way round.
I have a 4040 with 10inch sediment and 2 10inch jumbos with carbon filters. I have a 25 litre vessel with softner resin before sediment.
Tds in 480 @45psi out at 13 then through Di. Pure 1.2 a min- waste 2 litres a min
but i have to back flush the softner vessel about every 6-8hrs