TDS and Plastic containers

A question was raised at our April 24th meeting regarding the ion contamination of TDS=0 water when stored in a plastic container. The question was raised in regards to an experience that Jeff had when transporting RO/DI water in plastic containers and noticing a significant rise. I did a test to see if I could notice any contamination. My top-off container is plastic, specifically #5 plastic which is Polypropylene (PP). I first verified the operation of my portable TDS meter down to a TDS=1 by comparing it to the results of my in-line TDS meter on my RO/DI unit. I then tested the water in my storage unit that has not been filled in almost 2 weeks. Its a 25 gallon container that was down to approximately 10 gallons. The TDS of that water is still reading zero. So at least for "seasoned" PP plastic containers there does not appear to be a problem with contamination. Maybe different plastics and/or newer plastics will exhibit a problem.