How to install an under-sink water filter

• Adjustable spanners (two)
• Drill and bit for the tap hole, if needed
• Tube cutter or sharp knife
• Towel, bucket and torch

Before you start, lay everything out on a soft surface (the flattened box works) and check it against the parts list in your manual.

• Filter head and cartridge
• Tee valve or feed adaptor
• Push-fit tubing
• Filter tap, if supplied
• Mounting bracket and screws

1. 1

   Step 1: Turn off the cold isolator valve under the sink, or the main stopcock, and open the cold tap to drain the pressure.

2. 2

   Step 2: Undo the cold tap's flexible hose from the isolator, fit the tee valve onto the isolator, and reconnect the hose to the tee, using the washers supplied.

3. 3

   Step 3: Screw the filter bracket to the cupboard side at the height the manual gives, leaving room below to twist the cartridge out later.

4. 4

   Step 4: Fit the filter tap in a spare sink hole, or drill one if the sink material allows it, and tighten it from below.

5. 5

   Step 5: Cut the tubing squarely, push it fully into each push-fit connector until it stops, and follow the flow arrows on the filter head.

6. 6

   Step 6: Twist the cartridge into the head, then turn the water back on slowly and look for drips at every joint with a torch and dry tissue.

7. 7

   Step 7: Run the filter tap for the flushing time the manual gives before drinking the water, then write the date on the cartridge.

• Cutting the tube at an angle, so the push-fit connector weeps.
• Fitting the filter against the flow arrow.
• Skipping the flush, which leaves carbon fines in the first water.