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28440 Ag+ AntiMicrobial Logo HI RES CMYK

Challis Ag+ Sentinel Valve

Kills 99% Legionella, Pseudomonas, E coli*

"The facemask for taps"


*Independent Testing ASTM E 2149-20

How to Protect Your Tap Outlet From Pseudomonas & Legionella

Various reports over recent years have identified tap outlets and diffusers as a primary source of biofilm build up and subsequent proliferation of micro organisms such as Pseudomonas Aeruginosa and Legionella in tap diffusers and tap spouts.

This proliferation seems to be caused by two factors. Firstly the restriction of flow through diffusers and aerators encourages the build up of biofilm. Secondly the aeration effect of the aerator diffusers combined with splash back from the sink and drain hole facilitates vapour contamination of the tap outlet and subsequent back contamination of the tap spout.


Over the last few years various manufacturers have developed innovative, imaginative, complicated and expensive solutions to these problems.  From dramatic re-design of the sink, re-positioning the sink drain, right through to the complete re-design of the wash station with UV and digital readout. All these concepts overlooked the fundamental simplicity of the problem; how to prevent contaminated aerosol from back contaminating the tap outlet?

Why not physically seal off the outlet when it's not being used?


This is where Challis Ag+ simple approach to any problem resulted in a cost effective simple solution in the form of our patented Challis Ag+ Sentinel Valve™.  Our simple tap insert replaces the internals of your current tap diffuser. The Challis Ag+ Sentinel Valve™ is designed to enable the outlet to stretch open when water flow passes through and then seals shut when water flow ceases.

This innovative action means that the tap outlet is effectively closed and sealed when the water flow ceases, preventing any back contamination of the tap outlet or spout, by aerosols.

The Challis Ag+ Sentinel Valve™ is designed to be replaced every 6 months and combines seamlessly with our Challis Ag+ Shower Replacement Scheme or our Challis Ag+ Sentinel™ Shower Head & Hose.

A simple cost effective solution that can be quickly and easily retro fitted to any Tap, providing 24/7 anti microbial protection across your estate.

The Challis Ag+ Sentinel Valve™ is made from Food/ Medical grade Silicone which has the following properties:

  • Antimicrobial additive protection reducing risk of bacterial growth

  • High steam sterilisation resistance so can be autoclaved

  • Colour Coded (coming soon) to support improved compliance management

  • Patented Sentinel™ wire mesh 'bullet' providing additional antimicrobial properties

  • Excellent bio-compatibility already widely used in hospitals and medical devices such as catheters, implants and surgical reconstructive components.

  • Low chemical reactivity so can be safely cleaned with the broadest range of chemicals

  • Low toxicity

  • Superior resistance to heat and cold -30ºC to +350ºC

  • Durable with a high flex fatigue resistance for a long working life

  • High limescale resistance preventing biofilm build up

tap diffuser showing bacterial

Biofilm build-up on a tap-diffuser

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Tap comp flat image .jpg
Sentinel Valve Internal.jpg

No biofilm build-up on Sentinel™ mesh

Challis Ag+ Sentinel Valve. 
How Does It Work?

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19mm x 1.5mm o-ring.png
M22 & M21.5 adaptor.png
Silver Bullet.png
M24 & M22 Shroud.png
M24 & M22 adaptor ring.png

Sillicone 'O'Ring for use with

M22 & M21.5 Adaptor

M22 (external) & M21.5 (external)


Sentinel™ 'Bullet"


Sentinel™ Valve

M24 (external) & M22 (internal)

Chrome Plated Shroud

M24 (internal) & M22 (internal) Chrome Plated Adaptor Ring

Sentinel non-return Valve.png


24/7 Protection

Easy to fit

Antibacterial Medical Grade Silicone

Easy to Clean

Limescale Free

UV Proof

Cost Effective

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