How to Clean and Sanitise a Reverse Osmosis Water Filter Tank

A reverse osmosis storage tank should be sanitised at least once a year — ideally at the same time as your annual filter cartridge replacement. Here’s a practical step-by-step guide.

Browse our RO systems and replacement cartridges, or see our Reverse Osmosis Guide.

When to Clean Your RO Tank

• Annually — at the same time as your 12-monthly filter and membrane service
• After extended inactivity — if the system has been unused for more than 7 days, flush the system; more than 4 weeks, replace all filter cartridges
• If water tastes or smells off — unusual taste or odour from the RO tap is a sign the tank or filters need attention

Flushing After Short Inactivity (Under 7 Days)

1. Open the RO faucet and drain the storage tank completely.
2. Once the tank is empty, the RO system’s pump will activate and begin refilling.
3. Allow the system to flush for 10 minutes with the faucet open before closing it and allowing the tank to refill normally.

Full Tank Sanitisation (Annual or After Extended Inactivity)

You’ll need: food-grade sanitising solution (diluted white vinegar, hydrogen peroxide, or a commercial RO sanitiser), funnel, bottle brush, clean cloths, pliers or wrench.

1. Turn off the feed water supply valve under the sink.
2. Close the storage tank ball valve (quarter turn clockwise).
3. Open the RO faucet to release system pressure and drain remaining water.
4. Disconnect the incoming water line from the tank using pliers or a wrench. Place rags underneath to catch spilled water.
5. Prepare your cleaning solution: mix 1 cup of white vinegar with 3 litres of water (or follow the instructions on your commercial RO sanitiser).
6. Pour the solution into the tank using a funnel. Swirl to coat all internal surfaces.
7. Clean the tank exterior with a sponge and warm soapy water while the solution works inside.
8. Scrub the interior gently with a bottle brush to remove any accumulated debris.
9. Drain the cleaning solution completely.
10. Reconnect the water line, open the feed water valve, and open the tank ball valve.
11. Flush the first full tank through the RO faucet before drinking — this removes any residual cleaning solution.

Warning: Do not drink the first tank of water after sanitising. Use it for household cleaning or watering plants.

Frequently Asked Questions