2nd comments about flushing regularly , I always flush my system and have a tap on the pipe going into DI so I dont have to disconnect DI pipe every time ,I wait till TDS is down to 6 0r 7 then close tap and allow to go through resin . I have recently started using rainwater and find the flushing takes less time to get down to 7 or 8 ,rainwater comming in at 35 ish from storage tank. I have just fitted a booster pump between pre- filters and membranes and pure water out put has increased a fair bit. 25l container without booster pump took 110 mins ,with booster pump its down to 70 mins .The tds stays lower in my opinion as well when using booster pump.
I do often think of ladder days when I came home ,through ladders round back of house ,scrims in washer and that was it - now its a lot more messing when I get home but Im still not going back to Trad except for a few bungalows .I think my resin will last longer with using rainwater as our tap water comes in at 150-200 tds,