When the RO system fails for whatever reason and the backup DI system is placed online, should you bypass the DI tanks after all machines are through heat disinfect at the end of the night, like turning the RO system off, to save the tanks from depleating? I was told to turn the DI tanks off. If the RO system is offline and now the DI tanks are offline is the water flowing through the loop pure enough not to harm patients or is there a risk factor involved? I can't quite wrap my mind around this concept. An RO system has a DI backup for a reason and I feel like we might be introducing something into the loop that could potentially harm patients even though the loop will be divertded to drain and flushed before machines are turned on in the morning. Am I way off base having these concerns? Do any other clinics do this? Please, any insite as to pros and cons would be appreciated. Thank you.

Yes..turn the D.I. system off

Your thoughts and concerns are good. Here's two links that should help answer and clearify your questions.
Disinfect after bypass
backup RO pump/motor
As bikertech said, turn them off. Use them as needed until RO is repaired.

The water system can be turned off, but do not bypass what is making your AAMI quality water. All water entering the loop is required to be filtered by Carbon/RO or Carbon/DI/Endotoxin filter. You can not bypass the RO and bypass the DI.

There are a lot of different ways to set up a DI system. If you bypass the RO, the DI tanks can fill the RO Tank, you can close the valve at the end of the loop and operate the DI as a dead-end system, you can put raw water into the RO Tank and recirculate it through the DI, etc. Keep in mind that if you recirculate water through your DI from the RO Tank, you will not deplete the DI since it will be processing the same filtered water over and over again (except for some bicarbonate buildup from being exposed to the air). And, always disinfect before you return to the RO.