hummm... i would just buy distilled water. that'll get you 250 gallons
which will last you a very very very long time for your final rinse.

 

Well that's what I suggested back in Post #10
https://www.northamericanmotoring.co...8&postcount=10

But it opened up more questions than it answered...so now we come full circle, lol.

Actually the biggest problem I have buying distilled water is filling up one or two shopping carts and trying to make it to the checkout counter--then trying to fit that inside the MINI, lol.

 

It's a bit tough to pour distilled water out of the a jug to rinse off a MINI too

So nobody answered my question about the Sam's vs Costco machine

 

The smaller one can filter less water before the resin needs replacement. The large output ones do about 300 gallons. The smaller ones do 100.