Tap diffusers require regular maintenance and in some cases replacement as they can soon become blocked 
with limescale and consequently biofilm build up with Legionella and Pseudomonas
This sort of environment is also prone to back contamination as airborne water vapour droplets rise up from the basin and drain to further contaminate the outlet. The quickest easiest and most cost effective permanent solution to this problem is tho fit a Challis Ag+ Sentinel tap valve. Our patented technology combines our self sealing non return valve with our copper/silver mesh bullet which effectively prevents back contamination and disrupts the cell wall of micro organisms effectively solving your Legionella and pseudomonas problems.
The Sentinel Tap valve comes complete with a selection of adaptors including M24 M22 and M21.5. If you prefer you can use your old tap diffuser shrouds/thread. Once cleaned you can insert the new Sentinel tap valve internals into the old shroud to provide a perfect fit.
In order to identify if your tap needs a thread adapter and what size the thread adapter needs to be the quickest and most reliable method is to remove the current diffuser and measure the Outside OD diameter or Inside ID diameter in mm using either a ruler or digital callipers. 
Taking a photo of the diffuser next to a ruler and sending it to us is also a reliable option.
If we can be of any assistance please do not hesitate to call our Technical Team on 01628 529024 or email info@challisms.com. To Read More about how the Challis Ag+ Sentinel Tap Valve can help stop Legionella and Pseudomonas in your taps Click Here