How to Install an Under Counter Water Filter System

This guide is based on the installation of a Pozzani IX250 Water Filter system, however, the general installation method should be applicable for all under-counter water filter systems.


  1. 1
    Look under your kitchen sink and identify the cold water pipe feeding your cold tap. If you have a monoblock style tap with flexible hoses where it is difficult to determine which pipe is the cold main, run the hot tap for a couple of minutes, and you should clearly be able to see which is the warm pipe and which is the cold by touching the copper pipes.
  2. 2
    Ensure the section of copper pipe is suitable for installation of the saddle valve clamping device. This means check it is clean, free from corrosion or any nearby obstructions.
  3. 3
    Remove the saddle valve from the packaging - This is the device which looks like a small clamp, with tubing attached to it.
  4. 4
    Identify the diameter of the pipework - for a UK installation this will be 15mm or 22mm.
  5. 5
    Set the small mounting block from the clamp on the pipe - the side you use will be determined by the diameter of the pipe.
  6. 6
    Fit the clamp over the pipe and mounting block, and tighten the nut at the base (turn anti clock-wise).
  7. 7
    Take a bucket or similar receptacle, and place the red end of the tube into it.
  8. 8
    Turn the T-Bar handle on the top of the clamp clockwise fully down - this will pierce the copper pipe.
  9. 9
    Remove the filter housing, housing bracket and screws from the packaging
  10. 10
    Screw the bracket to a suitable part of the kitchen cabinet, you will need to check the dimensions of the housing to ensure it will mount.
  11. 11
    Open the filter cartridge supplied with the system
  12. 12
    Unscrew the filter cartridge housing
  13. 13
    Install the cartridge into the housing - cartridges are usually threaded or flat seal - flat seal cartridges simply sit in the housing and when its tightened up form the connections necessary. Threaded cartridges will screw into the head in an anti-clockwise direction.
  14. 14
    Re-assemble the filter housing.
  15. 15
    Mount the filter housing on the bracket
  16. 16
    Drill a suitable hole in the worktop or kitchen sink for the drinking water faucet/tap. For a standard touch tap (i.e. as shown in the image) you will require a 12mm hole.
  17. 17
    Seat the tap base over the hole - this neatens up installation
  18. 18
    Push the tap tubing through the hole (from the top side of the hole), and mount the tap into its desired position.
  19. 19
    Fit the tap washer over the tubing beneath the sink, and push up to the worktop/sink base
  20. 20
    Fit the tap nut over the tubing and turn anti-clockwise. Tighten up fully so the tap above the worktop no longer moves.
  21. 21
    Connect the red tube you have in the bucket to the input side of the filter housing - these are simple push fit connectors. Line up the tube with the red collet and push it home.
  22. 22
    Connect the blue tube from the tap to the output side of the filter housing - these are simple push fit connectors. Line up the tube with the blue collect and push it home.
  23. 23
    Carefully turn the T-Bar on the saddle valve anti-clockwise - this will allow water to flow through the red tube, to the filter housing, and on to the tap.
  24. 24
    Check for leaks - if leaks are found see the tips section
  25. 25
    Wait two minutes
  26. 26
    Turn on the drinking water tap, and allow the water to flow for two minutes. This is to prime/flush the new cartridge.
  27. 27
    Adjust the saddle valve to ensure optimum flow to 1.5 liters (0.4 US gal) per minute - turn clockwise to reduce the flow, and anti-clockwise to increase the flow.
  28. 28
    Installation is complete, continue to check the plumbing connections periodically for the next few days.


  • Before starting locate your stop tap - isolating the water isn't necessary for installation BUT should something go wrong it may be necessary to turn off the water supply.
  • When drilling through stainless sinks start with a small drill bit of about 4mm to create a pilot hole. Also, a thick tape, such as insulating or masking tape, placed over the hole position will help stop the bit from jumping and sliding on the initial drilling.
  • Consider your options - these days mono blocks with a third feed for filtered water are readily available - if you have an expensive sink or solid wood/granite worktops this may be a better option


  • Do not over tighten the clamping nut on the saddle valves - this may crush the copper pipe
  • Do not attempt to remove the saddle valve once the fitting has been made - this will expose the hole in the pipe causing a severe leak.
  • Don't install a saddle valve on plastic pipework - seek professional advice.

Things You'll Need

  • Drill, battery or mains - equipped with 12mm drill bit
  • Small adjustable spanner 3/8"
  • Posi-Screwdriver
  • Bradley or small drill bit for pilot holes

Sources and Citations


Article Info

Categories: Plumbing Drains Waste and Vents