How To Sanitize a Standard Undersink Reverse Osmosis Unit  (according to AI)

The very direct instructions created by an AI search are printed in bold type below. They  work great for our standard Black and White reverse osmosis units. They require some elaboration and modification  if you have an RO unit with disposable cartridge housings (like our Q Series units), one or more  disposable inline filters (like our “Economy” RO unit), or an encapsulated membrane (like any of our units with the 50/50 GRO membrane upgrade).
The AI instructions are in bold. See my comments in standard type below the AI instructions:

1. Turn off the cold water supply connected to the RO system.
2. Drain out the old tank of water through the dispensing faucet.
3. Remove all pre-filters (stages 1, 2, and 3) from their housings. Also, remove the membrane from its housing.
4. Scrub the inside of the housings with dish water and rinse thoroughly.
5. Add bleach into the housing of filter stage 1.
6. Install all empty housings and turn on the water supply.
7. Open the RO faucet until water comes out.

My comments’ numbers refer  to the topic number in the AI instructions.

1. On the Black and White unit, turn off the blue handled inline valve that feeds the Black housing.
2. If it doesn’t drain completely, now would be a good time to add some air to drive all of the water out. This isn’t absolutely necessary to sanitize the unit, but you’ll do a much better job if the tank is healthy.  See Pure Water Gazette » Reverse Osmosis Tanks Cannot Live Without Air
3. Remove the cartridges from the 2 or 3 vertical housings and the membrane from the horizontal housing.
4. This step is optional. Unnecessary if the unit is running on reasonably clean water.
5. About 3 tablespoons of household bleach is more than enough.
6. Turn the valve half way on and let the water fill the unit fairly slowly.
7. After you can smell bleach coming from the faucet, turn the water off and let the unit sit for a few minutes with bleach in it.  (The longer you wait, the more thorough the sanitation job will be.)

When sanitation is complete, turn off the inlet valve, open the faucet and let all the water drain from the storage tank. When the tank is empty, you can reinstall the filters and membrane (or replace them with new ones).  When everything is back in place, open the inlet, open the tank valve and close the faucet.  Let the RO unit fill the tank, open the faucet and let the tank drain, then close the faucet and the unit is back in service. When there is enough water in the storage tank, you can go back to using the RO unit as usual.

An Easier Way that Cleans Everything but the Membrane

1. Turn off the water, remove the filter housings, drain the storage tank.
2. Remove the black tube that goes into the In port of the shutoff valve. Remove from the tank tee the white tube that connects it to the shutoff valve.  Plug the black tube you just removed from shutoff valve directly into the tank tee.
3. Add bleach to the black housing, turn on water part way and let the unit fill slowly.
4. When the tank is almost full (judging by the reduced flow of water into the tank), turn the inlet water off, run water from the faucet until you smell bleach, then close the faucet and let the unit sit for at least an hour.
5. With inlet water off, open the faucet and let the tank drain completely.
6. Reinstall filters and put the unit back in service. When the storage tank if full, open the faucet and let the tank empty completely to rinse the unit.

If  you want to sanitize the storage tank only, here are some easy instructions.

Sanitize your reverse osmosis tank.

Sanitizing an Undersink Filter

A filter system is relatively easy to sanitize after an event such as a boil water alert.

1. Turn off the inlet water, open the faucet, remove the filter cartridges.
2. Put a couple of spoonfuls of household bleach into the inlet housing and put both housings back on without cartridges.
3. Turn on the inlet water and run water through the unit until you smell bleach coming out of the faucet.
4. Turn off the faucet and let it sit for an hour.
5. Turn off the water, open the faucet, replace the old cartridges with new ones.
6. Turn on the water, let the new filters rinse of four or five minutes, and close the faucet.  You are now back in service.