Mixing station/RO supply question

[RattlerSkin]

I am in the process of planning my mixing station build which will mean I get to move my RO/DI unit from the laundry room to the garage, which in turn means a much happier wife . Anyway, my mixing station will be a two-can setup consisting of brute trash cans and my current water supply line entering the house passes through a Culligan water softening canister which typically lasts us 15 days between replacement service.

My question is, should I have the hose adapter put in on the side before the Culligan softener, or after? As the setup is now, it is obviously after the softener since my RO/DI unit pulls water from the laundry room wash basin, but my concern is varying water quality since the canister begins to run low, then the water gets harder and leaves hard water stains on everything. I was thinking of putting my adapter on the pre-softener side that way I know for sure I am dealing with hard water and I can replace my sediment prefilter and carbon block without wondering how hard the water has been. Any ideas before I start cutting and soldering?

 

[chuckreef]

You should obtain the quaterly water quality report from your water provider. If the provided water is really hard, then having it pass through the softtener may help your RO membrane and DI resin last a little longer. If its not too hard, then either way is fine. E.g., if you have a 95% rejection rate and your TDS in is 100, you would have (ideally) 5 TDS out to your DI. (If your influent is really hard, you might have several times that amount.) Most RO systems are not designed for very hard water.

 

[RattlerSkin]

According to the formula SpectraPure provides I just figured with my 780 TDS in and 008 TDS out, I am getting 98.9% rejection rate when I have it running post-softener, so I am not going to even bother running it pre-softener. Definitely going to stick with post-softener on this one.