Found it. This is from Russ at Buckeye Field Supply:
We recommend sanitizing your RO/DI system approximately once per year. Schedule this process at a time when you are planning to replace your cartridges. These instructions apply to water purification systems without a pressure tank. Before you begin assure that you have about an hour available, and that your work area and hands are clean.
Turn off the water supply to the system.
Remove all housings and remove all pre-filters and post-filters from the system including sediment filters, carbon filters, in-line filters, and deionization cartridges. Remove the reverse osmosis membrane(s).
Wash housings with a soft brush or cloth in warm soapy water. Rinse thoroughly to remove all soap. Don’t forget to carefully remove and wash all o-rings. Lubricate the o-rings with a small amount of silicone grease and reinstall them.
Fill each vertical housing with one cup of potable water and three to four tablespoons of household bleach, and with this sanitizing liquid still in the housings, screw them back on to the system.
Turn on the water supply a bit, allow water to fill the entire system, and assure water is flowing out of the waste line and the purified water line. Place the outlet of the drain tube and purified water tube slightly higher than the system to assure these tubes are full of the sanitizing solution. When the sanitizing solution has reached the outlet of each tube, and with the outlet of each tube placed above the rest of the system, shut off the water supply for 30 minutes.
After 30 minutes, turn the water supply on and assure that water exits the system from both the drain tube and the purified water port. Flush the sanitizing solution from the system for 5 to 10 minutes.
Turn off the water supply and install new filters.
We recommend keeping a maintenance record for your system. Record the date of the sanitizing and filter replacement, and the reading on your pressure gauge with a new set of prefilters.
Russ @ BFS
