Wondering how to quickly and easily replace the filters in your reverse osmosis system?
We’ve shared the simple process for changing RO filters in this guide.
📌 Key Takeaways:
- To change a reverse osmosis filter, shut off your water supply and remove the old filter. Clean the filter housing, then lubricate/replace the O-rings and install the new filter.
- Replace the filters to this schedule:
- Change the sediment pre-filter every 6-12 months.
- Replace the pre-carbon filter every 6-9 months.
- Change the RO membrane every 24 months (2 years).
- Buy a new carbon post-filter every 12 months.
Table of Contents
🔂 How to Change Filters in a Reverse Osmosis System
Follow the below guides to change the filters in your entire RO system.
❗️ Before beginning, read through your system’s user manual. It’ll include detailed instructions that may be important to know for your specific unit.
How to Replace Carbon & Sediment Filters
To replace the carbon and sediment reverse osmosis filters in your system, follow these steps:
You will need:
- Replacement filter cartridge(s)
- Bucket
- Filter wrench (optional)
Step 1: Buy the new filters
First, buy the replacement filter cartridges for your system.
You could buy directly from the brand or from the brand’s Amazon page. You may be able to purchase non-branded filters that fit in your system (always check customer reviews).
Step 2: Wash your hands & Turn off your water supply
Wash your hands, then switch off the incoming water supply valve.
If you have a storage tank, close the storage tank valve. Additionally, if your system is connected to your ice maker or refrigerator, close off access to this valve, too.
Step 3: Drain the waterline
Switch on your dedicated RO faucet and wait for water to empty out of the system.
In preparation for potential leaks, place a bucket or a tray underneath the filter housing.
Step 4: Remove old filters
Unscrew the filters that need changing from the filter housing and dispose of them sensibly (many reverse osmosis filters can now be recycled).
You can use the wrench provided by your manufacturer if the filters are a little stiff.
Step 5: Remove & clean O-rings
Remove the filter housing and the filter O-rings, wipe them with a cloth, and place them on a clean surface.
👨🔧 Check the O-rings and make sure they’re still in good condition. Replace them with new O-rings (you can buy them from your local hardware store) if not.
Step 6: Clean filter housing
Clean the inside of the filter housing with soap and water. Dry thoroughly, then reattach the housing to your unit.
Step 7: Lubricate the O-rings
Lubricate the O-rings, then insert them back in the space you removed them from. Make sure the O-rings are correctly positioned to prevent leaking.
Step 8: Insert new filters
Unwrap your filter replacement, then insert it into the housing and screw it in place.
Either hand-tighten or use the provided filter wrench, but don’t force the filters too tightly.
Step 9: Turn on the water, Flush & test
Turn on your water supply valve and check that there are no leaks. If leaks are detected, tighten the RO filters a little more or check that your O-rings are properly positioned.
Switch on your faucet and wait for the water to flow through. If your system has a storage tank, don’t let water into it just yet.
Step 10: Fill storage tank (if applicable)
After allowing water to flow from the faucet for 5 minutes, switch off the faucet and open the storage tank valve.
Wait for your storage tank to fill, then open the valve connecting to your refrigerator or icemaker, if applicable.
Replacing the RO Membrane
To replace the RO membrane, follow these steps:
You Will Need:
- Membrane replacement
- Bucket
Step 1: Clean & prep
Follow steps 1-3 above, switching off your water supply and washing your hands before getting started.
Step 2: Disconnect tubing
Look on the right side of your filter housing for the tubing that connects to the membrane housing cap. Disconnect this tubing, pressing down on the small ring around the tubing as you do so.
Step 3: Remove old membrane
Unscrew the cap off the top of the RO membrane housing and ease the membrane out of the housing. You might nee to use needle nose pliers to remove the membrane if it’s stuck.
Step 4: Clean membrane housing
Disconnect the tubes at the other end of the membrane cap.
👨🔧 Tip: Color-code or label the tubes so you know where to insert them when you’re done.
Wash the inside of the membrane housing in a bowl of warm, soapy water, then rinse thoroughly. Dry the housing completely before reattaching it to your RO unit.
Step 5: Insert new membrane
Unpackage and install the replacement membrane in the housing. Make sure the end with the O-ring goes in first.
Keep pushing until you feel the O-ring make contact with the base of the housing.
Step 6: Replace membrane housing cap & tubing
Screw the cap back onto the membrane housing and connect the tubing you removed earlier.
Be sure to push the tubing into the fitting until it won’t go any further. Give the tubing a pull to ensure it’s locked in place.
Step 7. Flush, test & run the system
Follow steps 9 and 10 above to complete the installation.
Replacing An Inline Post-Filter
For a reverse osmosis filtration system that has an inline post-carbon filter installed horizontally next to the membrane, the process of replacing this filter is slightly different from replacing a sediment or carbon pre-filter.
This type of filter may have quick-connect fittings or threaded fittings, sized for tubing that’s either 1/4 inch or 3/8 inch.
Here’s how to replace an inline post-filter:
You Will Need:
- New inline post-filter
- Bucket
- Plumber’s tape
Step 1: Clean & prep
Follow steps 1-3 above to turn off the water and prepare the system for changing filters.
Step 2: Disconnect The Filter Tubing/fittings
Push down on the small ring connecting the tubing or fittings to each end of the filter. At the same time, pull the tubing. This should cause the tubing/fitting to come free.
Step 3: Unscrew Separate Fittings (Optional)
Some post-filters have a separate fitting on each end of the cartridge. In this case, once you’ve disconnected the tubing, unscrew the fittings on the filter. Use plumber’s tape to wrap the threaded male end of the fittings 2-3 times, then attach them to the new filter.
Step 4: Attach The Tubing
Push the tubing into each end of the new filter as far as it’ll go, then pull the tubing to make sure it’s properly attached.
Step 5: Complete Installation
Return to step 9 of “How to Replace Carbon & Sediment Filters” to complete the system setup after installing the filter.
📆 How Often Should You Change Reverse Osmosis Filters?
| Filter | Replacement Frequency |
|---|---|
| Sediment Filter | 6 - 12 months |
| Carbon Filter | 6 - 9 months |
| RO Membrane | 2 years |
| Polishing Filter | 6 - 12 months |
*Note that filter replacement schedule will vary depending on usage and local water conditions
Sediment Pre-Filter
The sediment pre-filter removes suspended contaminants like sand, dirt, dust, and rust.
For water supplies with average levels of TDS, a lifespan of 6 months to 1 year is about average for sediment pre-filters.
Carbon Pre-Filter
After the sediment pre-filter is the carbon filter. Carbon pre-filters use adsorption to grab aesthetic contaminants like chlorine, reducing them in drinking water.
An activated carbon filter has a lifespan of 6 to 9 months.
RO Membrane
At the heart of all reverse osmosis systems is the reverse osmosis membrane, which removes the majority of total dissolved solids.
Replace the reverse osmosis membrane after an average of 2 years.
Carbon Post/ Polishing Filter
The carbon post-filter removes lingering contaminants that may have passed through the RO membrane. Post-carbon filters also remove contaminants that may have leached from the storage tank.
Because the post-filter comes into contact with fewer contaminants, it usually lasts longer than a pre-filter. On average, you’ll need to make a filter replacement after every 6 months to 1 year.
🔀 Replacing Modular Filters In Reverse Osmosis System
If your reverse osmosis system contains modular filters, good news for you: the filter change process is much easier.
You don’t need to relieve pressure in the system or switch off your feed water supply before getting started.
Just place a bucket underneath the system and twist off the old filters. Replace them with new filters and check for leaks.
📈 Pressurizing An RO System
Check your RO system’s pressure tank – adjusting the pressure if necessary – when you replace a filter.
It’s normal for a pressure tank bladder to gradually use air pressure over time, so you will need to re-pressurize the tank every so often.
Learn how to pressurize your RO tank in this guide.
🧰 Additional RO System Maintenance
Aside from replacing the filters and pressurizing the RO tank, there are a few other maintenance tasks to remember.
The most important task is to sanitize your RO system around once a year. You should also check the structural integrity of the system, especially the storage tank, and make repairs or replacements when necessary.
Related: How to Clean & Sanitize a Reverse Osmosis System (step by step instructions)
❔ Frequently Asked Questions
How do I know if my reverse osmosis filter is bad?
Signs that your reverse osmosis filter is bad are low water pressure from the system (indicating clogging), a bad water taste (suggesting that your reverse osmosis filter can’t produce the same high-quality purified RO water), and more wastewater from the membrane than usual.
Why do you need to change an RO water filter?
You need to change an RO water filter to keep the system in working order. Without filter changes, the filters would eventually become so clogged that no water could pass through, reducing filtration speed and increasing water waste.
How long does an RO membrane last?
On average, reverse osmosis systems have a membrane lifespan of 24 months. You may need to replace the membrane more frequently if your water’s TDS and turbidity are particularly high.
What affects the lifespan of RO water filters?
Factors affecting the lifespan of an RO water filter include your water usage, the filter size and surface area, and your water quality.
How much do replacement RO filter cartridges cost?
The cost of a filter replacement depends on the brand you’re buying from. You can usually buy a pack of all the filters you need for $60-$100. RO membranes on their own cost $30-$75.
