Issues with RO unit

[Brady]

Hi everyone,

I'm in some desperate need of help here. I've had a RO unit for a long time, however, I've recently moved and I'm on a well. My incoming TDS is about 650. The thing that is really confusing me is the drain water coming out of my RO drain line is 1000. After membrane I'm getting 100 TDS which is only 90% (all brand new filters, including membrane). Why is the TDS on the drain line on my RO unit much higher than my main line?

 

[phg1960]

Actually that's normal. The output water is the 600 TDS water in plus what is being rejected by the membrane. Your efficiency is only about 83% though. How much water have you run through the new membrane? It is common to have high number for the first 5 - 10 gallons.

 

[Brady]

I've only run about 4 gallons so far.

 

[Jim Tansey]

Hate to say this but your not going to clean up some well water, you will run through membranes in a week. Been their done that!!

Jim

 

[phg1960]

Check the number again after ten gallons or so. I would expect the output TDS to lower.
The tap water TDS in being lowered by the sediment and carbon stages also. So the best way to figure the efficiency of the membrane is to take a TDS reading at the membrane input and at the output to get a true rejection ratio.

 

[Brady]

ok, sounds good thanks for the help

 

[Spudsly]

I'm grappling with something similar. I'm working on optimizing my rodi, my well seems to spit out roughly 200TDS water (after going through the first house fiber filter). My output seems to be about 15. I just ordered new DI resin and I'm going to see if that helps.