1. Turn the tap on
  2. Shut the water supply off. If you have a saddle valve it is simple as turning the needle valve clockwise until the water flow stops (water will stop flowing from the tap). Alternatively you can turn the water off at the mains.
  3. Although the tap will have drained most of the water in the lines, there will be some residual water so it might be a good idea to put a towel down to absorb any water that drains from the cartridge or line.
  4. Using your fingertips, pinch and push the pushlock fitting inwards (towards the cartridge) while at the same time pulling the tubing out of the fitting (away from the cartridge). This is quite tricky the first time around so it might take a few goes.
  5. Take out the old cartridge
  6. Taking note of the directional flow arrow on the cartridge, put the new cartridge in.
  7. Take the two ends of the tubing and push them into the cartridge ends