Reverse Osmosis Cleaning: How to Sanitize Your RO Filter

How to Clean and Sanitize Your Reverse Osmosis Filter

Do you have a reverse osmosis system? If so, the topic of reverse osmosis cleaning has probably come up in conversation.

Over time, your RO filter can become fouled by scale buildup, mineral deposits, biofilm growth, and sediment. It may also have bacteria growth in the water storage tank or other components. These issues can result in bad tasting water, poor filter performance, or even illness.

This article will teach you everything about cleaning and sanitizing your RO filter. You’ll learn what types of fouling problems there are, how to clean and sanitize your RO filter, and how often you should do it.

Continue reading to learn how to properly clean and sanitize your RO filter!

Types of RO Fouling Problems

There are several types of fouling problems that can occur in a reverse osmosis system. The most common ones are scale, mineral deposits, and biofilm. It is important to know what type of fouling problem you have so you can tailor your cleaning approach to get the best results.

1. Scale

Scale buildup is a common fouling problem in reverse osmosis systems, especially in areas with hard water. Hard water contains high levels of minerals, such as calcium and magnesium.

These minerals can deposit on the RO membrane, causing a decrease in water flow and an increase in system pressure. Scale can also clog the filters and storage tank, resulting in loss of water purification, shortened filter life, and reduced water flow through the filter.

2. Iron and manganese foulingIron Staining on RO membrane

Water that contains a lot of dissolved iron or manganese can cause fouling of RO membranes and pre-filter cartridges. These metals create deposits that can be so thick that they block water flow, damage components in your system, and lead to early filter failure.

If you see orange/rust-colored stains on your plumbing fixtures, you have iron in your water. If the color is black, then you likely have manganese. The presence of either of these metals in your water means you will have to clean your RO system to remove accumulated deposits.

3. Biofilm growth

Biological growth can build up on membrane surfaces, reducing the amount of water that flows through your system. It can also clog filters and your water storage tank.

The best way to prevent biofilm growth is by regularly cleaning your RO filter with a strong oxidizing agent like hydrogen peroxide or chlorine bleach. This will kill most microorganisms in your system so they won’t be able to grow and form biofilms.

4. Bacteria

Bacteria can grow in the water storage tank or other components of your reverse osmosis system. This can lead to bad tasting water and even illness.

The best way to prevent bacteria growth is by regularly cleaning your RO filter with a sanitizing agent like chlorine bleach. This will help neutralize the bacteria in your system so they won’t be able to grow and contaminate your water.

Check out this video on sanitizing your RO filter system.

My Reverse Osmosis System

I’ve had a reverse osmosis system for my home for about a year now. I installed it because my tap water has lead and PFAS in it. Fortunately, this RO filter removes 100% of both contaminants. It give me and my family comfort to know our water is safe to drink.

You may want an RO system like this for your home.

Check Pricing on Amazon

Importance of Cleaning Your RO Water Filter

Keeping your RO system clean is important for several reasons.

  1. Reduced water flow: If you don’t clean your system regularly then you may experience reduced water flow and lower production of filtered water over time.
  2. Bad tasting water: Dirty filters can lead to poor tasting water that makes it unpalatable to drink or use in cooking.
  3. Shortened filter life: Fouling of your system may shorten the life of your RO membrane so much that you’ll have to replace it more often than usual.
  4. Reduced system efficiency: Scale, mineral deposits, and biofilm can all clog filters and other components in your RO system, resulting in reduced contaminant removal.
  5. Illness: If bacteria growth is allowed to continue unchecked, it can contaminate your drinking water and make you sick.

Reverse Osmosis CleaningFouled RO membrane

Regular cleaning of your RO system will help prevent fouling and maintain its peak performance. Cleaning should be considered part of the routine maintenance of your RO filter.

There are several methods you can use to clean the components in your reverse osmosis filtration system as outlined in the following sections.

Cleaning the RO membrane

The membrane is the heart of your reverse osmosis system. Keeping it clean and in good condition is critical to having clean and pure water.

There are several ways to clean your RO membrane:

  • Manual flushing: This is the most basic way to clean your membrane. Simply disconnect the inlet and outlet hoses from the filter housing, turn on the faucet, and let water run for a few minutes. This will help flush out any accumulated deposits on the membrane surface.
  • High pH cleaning: If your membrane is fouled by biological growth, a high pH chemical solution can help break up the biofilms. Sodium hydroxide is commonly used because it is relatively inexpensive.
  • Low pH cleaning: Fouling caused by iron, manganese, or calcium can be readily dissolved with a mild acid cleaning agent. Citric acid is frequently used because it is relatively mild and quite effective.

In some cases, you may have to use some or all of these methods to clean the RO membrane. If you have a small, under-sink unit, cleaning may not be possible because the RO cartridges are too small and are made to be disposable. In this case, you will have to replace the RO cartridge.

Cleaning the RO water storage tank

RO storage tanks should be cleaned periodically to ensure that they’re free of debris and mineral buildup. I clean my tank annually.

You can clean the tank with a mild acid solution such as vinegar or citric acid because it won’t damage the plastic container. Before cleaning, make sure your unit is turned off and there’s no water in the system.

After cleaning, make sure you rinse the tank thoroughly to remove all traces of the acid solution.

Cleaning the RO system pre-filters and tubing

Your reverse osmosis system has several additional filter elements that may need occasional maintenance: sediment filters (fine mesh), carbon block pre-filters, post carbon/pre-carbon activated charcoal cartridges, and deionization (DI) resin cartridges.

Cleaning RO filters of under-sink units is not possible. You simply replace the spent filter with a new one.

Whole house RO systems often have filter elements that can be cleaned by backwashing them. Eventually, the filter elements must be replaced with new units.

Chemicals to Sanitize Your RO Water Filter System WithSani System

Sanitizing your RO system is important to keep bacteria and other types of microorganisms from growing in it. If you don’t clean and sanitize your filter properly, bacteria can multiply and contaminate the water flowing through it. Sanitation methods should be done each time before backwashing or flushing because this removes harmful contaminants that could otherwise damage parts inside the filtration system.

  • Sodium hypochlorite (household bleach): This is a simple and inexpensive way for small systems with only one or two cartridges. Mixing sodium hypochlorite at about ten percent concentration will provide enough sanitizing power without damaging filter elements.
  • Hydrogen peroxide: This is a good choice for systems with more than one cartridge. Hydrogen peroxide can be used at full strength and doesn’t harm most filter elements.
  • Sani-System sanitizer: This is a food-grade cleaner that is proven to kill 99.99% of harmful bacteria.
  • Vinegar: If you want to avoid harsh chemicals, a solution of three percent white vinegar will effectively sanitize your RO system. I prefer to use bleach or hydrogen peroxide, but many people swear by this cleaning agent.

Sanitizing concentrate – cleaning fluid

This liquid concentrate works for reverse osmosis systems and water softeners. Just mix it with water and add it to your RO filter as explained in the instructions.

Check Pricing on Amazon

When to Clean and Sanitize Your RO System

You should clean your RO system before it becomes fouled or plugged. There are indicators that you can monitor to know when it’s time to clean your filter.

  1. Reduced flow: a fouled filter will experience a decrease in the production rate of clean water. If you notice a drop in the flow rate, it’s time to clean your system.
  2. Reduced pressure: as the RO membrane becomes fouled, the discharge pressure will drop off. This is a signal to clean the membrane.
  3. Bad taste: a fouled membraned loses its ability to purify your water. Changes in the taste and quality are signs that it’s time for a cleaning.
  4. Odors: a properly functioning RO system will remove impurities that cause foul odors. When you notice an off smell, it’s time to clean your RO membrane.

How Often Should You Clean Your RO Systems

You should sanitize your reverse osmosis system once each year. This will destroy harmful bacteria that might be growing in your water storage tank or on the filter elements. If you perform service on any of the components, such as replacing a filter or replacing a hose, you should sanitize your system to prevent unwanted bacterial growth.

Most manufacturers have a recommended cleaning frequency for the RO membrane. Check the owner’s manual for their guidance.

In general, it is a good idea to thoroughly clean your RO membrane while replacing the water filters. Most RO system require changing the filters every 6 to 12 months.

Tips for Keeping Your RO Filter Clean

Maintaining the cleanliness of your reverse osmosis (RO) system is essential for optimal performance and water quality. The following table presesnts 7 essential tips to help keep your RO filter clean.



Replace the pre-filters

Regularly replace pre-filters, usually every 6-12 months, to trap sediment and particles before they reach the RO membrane. Check the manufacturer’s recommendations.

Monitor the RO membrane

Keep track of the total dissolved solids (TDS) levels to ensure the membrane is functioning efficiently. Replace the membrane, which can last 2-3 years with proper care, as needed.

Flush your system

Periodically flush your RO system to remove built-up contaminants. Follow the instructions in your system’s manual for automatic or manual flushing.

Sanitize the system

Annually sanitize your RO system using a food-grade sanitizer to eliminate bacteria, algae, and biofilm growth. Follow the manufacturer’s guidelines.

Inspect the storage tank

Regularly inspect the storage tank for leaks, corrosion, or damage. Ensure the air pressure inside the tank is at the recommended level to avoid water stagnation.

Keep your system cool and dry

Store your RO system in a cool, dry place, away from direct sunlight and heat sources to prevent damage to the membrane.

Avoid harsh chemicals

Use mild soaps or detergents instead of harsh chemicals or abrasive cleaning tools when cleaning your RO system’s components to avoid damaging delicate parts.


Final Take on Cleaning and Sanitizing RO Filters

In this blog post, we’ve covered the importance of cleaning your reverse osmosis system and how to perform a thorough cleansing. We discussed fouling problems that can occur with RO systems and what you should do if they happen to you. Finally, we gave some general guidelines on when it is best to clean or sanitize your filter depending on its type of filtration media used. Now that you know all about RO filters, get out there and clean your system!

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children. You can also follow him on LinkedIn, Twitter and Facebook.

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