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How to Change a Cartridge Type Filter in a Water Filtration System

Water filters come in all shapes and sizes. Most filters are changed basically the same way. For best performance change your water filter at least every six months to one year.


  1. Close the cold-water water valve that feeds the filter.
  2. Release any pressure in the line by turning on the water faucet that is after the filter, and leave it open. Some filter models also have a vent valve on top of the filter that you press to release pressure after you shut off the supply water.
  3. Turn the sump counter-clockwise using the sump wrench that came with the filter to remove it. Be careful: It's full of water, you may want to put a bucket underneath just in case you spill some water.
  4. Locate and set aside the O-ring seal.
  5. Remove and throw away the used filter cartridge.
  6. Clean the inside of the sump with hot, soapy water and rinse it very well.  Remember that you turned the water off at the sink you're working on, so you will need another water source.
  7. Pre-soak and Insert the new filter cartridge in the sump. Check the label on the filter - some are designed to be installed in a specific direction.
  8. Grease the O-ring with clear silicone lubricant. Be sure that it seats completely in its groove.
  9. Line up the sump with the filter head and screw it back on.
  10. Tighten the sump by hand only, turning it clockwise.
  11. Label the sump with masking tape and date it with todays date.
  12. Open the water valve slowly and fill the filter. If you have a vent valve, hold it down while the filter is filling to keep air out of the line.  Close the faucet once the air has escaped and the water flowing from it has stopped sputtering.
  13. Turn off the faucets and check the unit for leaks.
  14. Run the water for 5 minutes into a drain to clear out particles that are in the cartridge.


  1. Once your filters have been changed, with the water feed still in the off position, drain the water from that tank via the dedicated faucet RO faucet at your sink.
  2. Using a fine pressure gauge, test the pressure from the small pin valve at the bottom of the tank. The pressure should be between 10-12psi.
  3. If it is lower than 10psi, disconnect the tank and close to valve at the top of the tank.
  4. Using a small compressor or biclyle tire pump attached it to the tanks pin valve and re-pressurize slowly, testing every 15 seconds to be sure you do not put too much air in as the bladder inside could burst.
  5. Once you have reached the desired pressure, replace the small black cover over the pin valve, reconnect your tank and open up the valve on the top of the tank.
  6. It will take about 2 hours for your tank to fill with water. Drain out the first tank full to flush out the filters. Your second tank full will be ready to drink.

We recommend to drop by the store with a water sample about 1 week after your filter change so we can test your water to ensure you are drinking the best water possible from your filtration system.


Tips & Warnings

The sump is the tall, cup-shaped, reservoir part of the filter.

If you don't have a sump wrench, you can use adjustable pliers, but wrap a soft rag around the    sump first.

If the sump won't screw back on, turn the filter around - you may have it in upside down.

If the unit leaks after reassembly, turn the faucets back on, close the water valve, take the pieces apart, and remove the sump again. The culprit is usually the O-ring slipping out of its groove.

Keep a bath towel handy - just in case.

Be very careful not to cross-thread or over tighten the sump(s) or you may have a flood on your hands.


If this looks too complex for you or you would just rather have someone else do it, contact a Water Superstore trained service technician today.