Pro Tips Series #3: How to Maintain and Sanitize Your Reverse Osmosis System

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Clean Hands. Clean Filters. Clean Water.

A reverse osmosis (RO) system can deliver some of the purest drinking water in your home — but only if it’s properly maintained. Neglecting filter changes, skipping sanitation, or even handling cartridges with unwashed hands can shorten membrane life and allow bacteria to grow inside the system. Follow these professional tips to keep your RO system running efficiently and safely.

Understanding Your RO System

1. Wash Your Hands Before Changing Filters or Wear Nitrile Gloves

Before servicing your RO system, wash your hands thoroughly with soap and warm water. Even microscopic bacteria from your hands can contaminate filter housings or lines, especially since RO systems operate in dark, damp environments ideal for bacterial growth. A few seconds of handwashing helps ensure your filtered water stays clean from the start.

2. Replace Sediment and Carbon Filters Every 6 Months

Routine filter changes protect your RO membrane — the heart of the system — and keep your water tasting fresh. Replace these components every six months:

  • 5-Micron Sediment Prefilter — captures sand, silt, sediment, and rust particles.
  • Carbon Prefilter — removes chlorine, odors, and volatile organics that degrade the membrane.
  • Post-Carbon Filter (Polishing Filter) — refines taste and odor before the faucet.

Changing these filters on schedule maintains system flow, pressure, water quality, and long-term membrane performance.

3. Check TDS Before and After Every Filter Change

HM Digital TDS-3 Handheld TDS Meter

This is the TDS meter I've used for years and I trust to be accurate. 

Affiliate Disclosure: The Water Softener Blog may earn a small commission if you

purchase through affiliate links. This helps support our mission of providing

consumer-first, unbiased guidance on water treatment.

A TDS (Total Dissolved Solids) meter is your best diagnostic tool for RO performance.

  • Record the feed water TDS and RO product water TDS before filter changes.
  • Measure both again afterward.

Stable or improved results confirm correct installation. If your RO water TDS rises sharply, recheck filter placement or inspect the membrane for fouling. The TDS of RO water should always be 80% or higher compared to the feed water. When the TDS drops below 80% rejection, it is time to change the RO membrane.  

4. Sanitize the RO System Annually


Sanitizing removes bacteria and biofilm that can accumulate inside the housings, tank, and tubing. Perform this at least once a year — or whenever you replace the membrane:
  1. Turn off the feed water and drain the storage tank completely.
  2. Remove all filters and the membrane.
  3. Add a few tablespoons of unscented household bleach or a specialized RO sanitizer into the empty prefilter housing.
  4. Do this without the membrane in place, as chlorine can damage it.
  5. Reassemble the system (without filters or membrane), open the feed valve, and let it fill.
  6. Once filled, turn off the water and let the sanitizing solution sit for 30 minutes.
  7. Flush the system thoroughly, then install new filters and the membrane.
  8. For systems with one-piece filter cartridges, empty filter housings are often available for sanitizing. Check your manufacturer’s website or contact them directly for “dummy” housings designed for this purpose.

5. Flush Thoroughly After Replacing the Membrane

  1. Change the RO membrane every two years, or when TDS rejection drops below 80%. This ensures continued high-quality water production.
  2. New membranes are preserved in a mild disinfectant (sodium metabisulfite).
  3. After installation, fill and drain the storage tank twice to remove the preservative completely.
  4. If your system includes a membrane flush valve, run it for several minutes after changing filters and the membrane to flush the membrane of disinfectant, flush carbon fines, and restore water quality and RO system performance.

6. Inspect the Storage Tank and Tubing

  • Check that the tank air pressure is around 7–8 psi when the tank is empty.
  • Examine tubing and fittings for leaks, brittleness, or discoloration.
  • Replace any components that appear worn — this prevents contamination and ensures reliable operation.

Pro Tip Recap

  • Wash hands before servicing or use Nitrile Gloves — Every filter change
    Prevents bacterial contamination.
  • Replace sediment & carbon filters — Every 6 months
    Extends membrane life.
  • Check TDS readings of feed water and RO water— Each service
    Verifies system performance.
  • Sanitize system — Annually
    Removes bacteria and biofilm.
  • Flush after membrane change — Every 2 years
    Removes preservatives and debris.
  • Inspect tank & tubing — Annually
    Prevents leaks and contamination.

Your RO system only performs as well as the care you give it. By washing your hands before servicing, changing filters regularly, monitoring TDS, and sanitizing annually, you’ll ensure your RO unit continues to deliver crisp, clean, and safe drinking water.

When it comes to maintenance, remember:
Clean hands. Clean filters. Clean water.


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