RODI Question

[koddyVT]

Is the waste/reject water from the RODI unit the same quality as the tap water before it ran through the unit or does the waste water pick up extra additives as it runs through the unit? I don't think that anything is picked up when the water passes through the standard filters but what about as it moves through the deionization resin or the membrane?

I checked the TDS and it appears that the tap and waste water are the same in terms of TDS but I know TDS does not give the entire picture. I am curious because I am trying to find other uses for the waste water.

Thanks!