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How To Change a Filter Cartridge in a Reverse Osmosis System

ro filter replacement

Check the filter lifespan for your particular RO system in the user manual.

I also recommend buying a TDS meter. It’s the best way to monitor filter life.

Take a reading after you install the system and then every month after. When the TDS readings start to go up, it’s time to replace the filters.

The Importance of Replacing Filters on Time

how to change a water filter

It’s better to replace the filters too early than to do it too late.

Delaying filter replacement reduces the quality of your drinking water and reduces the durability of the entire system.

As the filters clog and age, they’ll start to allow more and more impurities through.

These contaminants include suspended particles that clog the RO membrane and chemicals like chlorine that damage it.

Over time, your RO membrane will start failing as well, letting through bacteria and other impurities.

This puts you and your family at risk.

That’s why I highly recommend a TDS meter.

Buying the Right Replacement Filters

Reverse Osmosis filters

Buy the replacement filters well ahead of time or when you are ordering the RO system.

This ensures you have spare filters on hand in case the company goes out of business or for some reason, and you can’t order new filters.

Most RO system manufacturers sell spare filters in sets. You can get a set of all the filters or a complete set containing the filters and the RO membrane.

If you are replacing the membrane, you can usually buy it separately.

Make sure you buy the right filters. Check the manual for the name and model of the manufacturer-recommended replacement set.

When you are buying the replacement, also check which RO models they are compatible with. If you are not sure, contact customer support.

Finally, you should only buy replacement filters from the manufacturer or an authorized reseller.

Replacing the Filters

Sanitize RO system

The following are general guidelines. The specific filter replacement process differs slightly for each RO system.

Read the user manual for specific instructions that apply to your system.

Generally, you don’t need any tools to replace filters. But some RO systems come with a wrench that you can use to loosen the filter housings.

  • Turn off the water supply to the RO system at the feed valve. Also, close the valve leading into the reserve tank. If you have water going to the refrigerator or icemaker, turn off that valve as well.
  • Relieve pressure from the RO system by turning on the RO faucet.
  • Place a pan or rag under the filters to catch any dripping water.
  • Before you proceed, wash your hands with soap and water to avoid introducing any bacteria into the system. Also, make sure you don’t open the new filters until you are ready to install them.
  • Unscrew the filters by turning them anticlockwise with your hands or with a filter wrench. Do not tip the filters as they have water in them.
  • Remove the used filter cartridges and discard them. Also, remove the O-rings and set them aside on a clean surface.
  • Rinse the filter housing using warm water and mild soap.
  • Set the filter housing aside and inspect the O-ring. If it is damaged in any way, replace it. If it looks good, wipe it with a clean towel, apply some silicone lubricant, and put it back onto the filter housing.
  • Open the new filter cartridge and insert it into the filter housing.
  • Screw the filter housing back into place, making sure not to over tighten.
  • Turn on the water feed valve and check for leaks.
  • Before turning on the storage tank valve, let several gallons run through the system and out of the faucet to flush the new filters.
  • Turn on the storage tank valve and icemaker valve.

Note: If you have a Home Master system or any other RO unit that has all-in-one filters, you replace the entire filter (the housing plus the cartridge).

Replacing the RO membrane

ro filters replacement

Most RO membranes need to be replaced every 2-3 years (3-5 years for Home Master systems).

To replace the membrane, start with the above steps up to where you wash your hands (turn off the water, turn off reserve tank valve and ice maker valve if applicable and relieve pressure by opening faucet).

  • Identify the RO membrane housing. It will be labeled.
  • Disconnect the tubing from the RO membrane by pressing down on the ring around the connector and gently pulling the tube out.
  • Unscrew the cap and remove the RO membrane. You may need to use needle-nose pliers to pull out the membrane.
  • Remove the packaging from the new membrane and insert it into the membrane housing. Make sure your hands are clean to avoid contamination. If you have a pair of needle-nose pliers, use those to hold the end of the new membrane and insert it into the housing, making sure it is oriented correctly.
  • Screw back the cap and push the tubing back into place.
  • Open all valves and let the tank fill twice. Drain the tank both times by opening the faucet. After the third filling, you can drink the water.

Replacing the Post Filter

In-line carbon post filter

The in-line carbon post filter is replaced every 6-12 months. In most cases, you replace it along with the pre-filters.

Again, follow the initial steps outlined above.

  • Disconnect tubes from both ends of the filter by pushing down on the rings and pulling the tubes out.
  • Discard the old filter.
  • Take the new filter, remove the protective plugs from both ends, and position it where the old filter was.
  • Reconnect the tubes and open all valves.
  • Discard the first two tanks of water to get rid of all carbon fines.
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