Usually if your tap is dripping from the spout then you need to
Change the valve: Hot or Cold (or both) – if you have a Two Lever Tap
or Cartridge ( if you have a Single lever tap)
Which Valve is faulty?Hot or Cold?
The definitive way to check is to isolate each water feed in turn and thereby establish exactly which Valve (or both) is dripping. The following tip is only where you are unable to do this so it is rudimentary and not exact. Without removing the valves to see if there is any thing obvious on your valve to indicate that it is worn, you could run the hot water in your tap. Then turn it off and see if the drip continues to be warm or turns cold. If it turns cold then it is most likely the cold valve that is the problem. If it remains hot then it is most likely your hot valve.
A triflow tap has 3 valves , one for the hot side, one for the mains cold side and one for the filtered cold side. Usually the filtered cold valve and the mains cold valve are the same. If you have a filtered tap with 3 valve and you have narrowed it down to a problem on the cold side then it is far harder to distinguish which cold valve is at fault i.e. mains cold valve or filtered cold valve. What you could do is buy both valves and try the new one in both i.e. test it in one and if drip continues test it in the other one and see which ‘cold’ valve needs replacing. Remember that if you fit a new valve then it is ‘used’ and can’t be returned for a refund if not required.
Summary of useful guides:
Our complete section of Guides / Plumbing Tips can be found in the Helpful Tips section. These have been written with the home DIY person in mind so we have tried to keep technical information to a minimum.