RO/DI reaction?

[Cory]

I went away on vacation for 24 days. To be safe I turned off the water supply to the RO/DI. During this time the water was off. So I go back from vacation and turned on the water. Strange though because the input water is cold, but in the housing it feels warm, and comes out after the di as being warm water! Tds reads zero. Problem is I drink this water, is it safe? Why is is warm?

 

[AZDesertRat]

It will be warm until you run a few gallons through and purge the water out that had been sitting in the system. Disconnect the DI for the first few gallons of RO so you don't exhaust the resin prematurely with the TDS creep that has built up. If you re using it for drinking, place a tee and ball valve between the RO membrane and the DI filter so you can draw RO only water for drinking.

 

[Cory]

Thanks a lot. It's good to know that's normal.

 

[AZDesertRat]

In general, try to use the system at least every 10-14 days so it stays fresh. If you will be down for an extended period it is a good idea to remove the RO membrane and DI cartridge, place them in Zip Loc type bags with a little RO/DI water so they stay wetted or damp and place them in the refrigerator. Reinstall the RO membrane first and flush it for awhile before installing the DI and you sould be good.