I have a 4 stage RO system...

[thall17]

I have made roughly 100-150 gallons, the first few collections measured 0 with a TDS meter. The water has been sitting for maybe 3-4 weeks in a 55 gallon plastic drum and just out of curiosity I tested today an it's measuring 3. Is it ok to use? Could the water be getting "contaminents" from the air for sitting uncovered? What does everyone store there RO water in?

 

[Crabs McJones]

Is the plastic drum food grade?

 

[Fish Fan]

I think this is perfectly fine. RODI water is nearly pure, and pure water is very reactive. It will react with things in the air, but I don't think this is a concern. I'm almost positive @Randy Holmes-Farley said so in another thread. Maybe he can stop by here and confirm if he has a minute

I hope this helps!

 

[thall17]

They stated that it was yes