Arboles UK, AUK 3 Category 5 and you – a quick guide.

Do I need to be aware of AUK 3 Category 5?


Are you planning a new laboratory, responsible for an existing laboratory? Then in short the answer is ‘Yes, yes you do!’. This doesn’t mater whether it’s private enterprise or within the education sector or anything in between – you need to know this!


The ramifications of non compliance can disrupt productivity for industry, disrupt vital experiments for education, if the laboratory is condemned then it’s stress you do not need and ultimately, the worst case scenario is that it can cost you a lot of money and aggravation!


Where did the AUK3 Category 5 regulation come from?


The regulation came into force under the Water Supply (Water Fittings) Regulation 1999. This has been kicking around for a good few years now and ultimately it is there to protect the water supply from contamination from experiments by the rare occurrence of something called ‘back siphonage’. This is where a chemical or other contaminant (such as bodily fluids) can be introduced back into the water supply by an influx of air by a sudden drop in mains pressure thus contaminating it. It is rare, BUT it has happened.


Category 5 in short:


The below is designed to offer an introduction to what is required and offer some basic understanding into the standard.


All laboratories must comply with the National Water Supply Regulation. Within these regulations laboratories must be protected by AUK3 category 5. It is worth a mention that AUK3 category 4 is not acceptable and this has been recently clarified by the national water companies in conjunction with WRAS.


Action is required if there isn’t a dedicated supply present via a break tank. The appropriate statutory air gap should also be incorporated within the tank. It is imperative to liaise with the local water inspectors to ensure compliance before starting any remedial work.


If the above break tank arrangement is not available then the below should be taken in the following circumstances:


  • Serrated nozzle taps suitable for the connection of rubber hoses are connected directly to the mains supply.
  • If a secondary room which is not a laboratory has been connected to the same supply.


The following options are available if any of the above applies.


  • Install a dedicated Break tank with the statutory air gap.
  • Change the nozzles from serrated to aerated to ensure rubber hoses cannot be fitted. Our aerated nozzle is here
  • Install an Arboles fully approved anti-siphon nozzle to all taps.


Arboles UK - Anti Siphon Nozzle - 900100-W

Arboles UK – Anti Siphon Nozzle – 900100


Our anti siphon nozzle is designed specifically to protect the water supply from back-siphonage EVEN when a hose is fitted. Some manufactures are offering “DC” pipe interrupters as AUK3 Category 5 compliant with WRAS approval. Strictly to the letter this is true, however, great care should be taken to ensure rubber hoses are not connected to these products, as “DC” pipe interrupters no longer comply.


Other considerations:


Are the existing taps compatible with our Anti Siphon Nozzle?

The anti siphon nozzle (product code 900100) requires a ½” male BSP thread to connect to. If you’re unsure what is compatible here have a look at these two favourites:

Swan neck tap (cold water feed) 902103

Pillar bib tap 900121


Arboles UK - Pillar Bib Tap with Anti Siphon Nozzle (900100)

Arboles UK – Pillar Bib Tap with Anti Siphon Nozzle (900100)


Putting our money where our mouth is – here.


If you have any questions please feel free to give us a call on 01204 388 814 or get in touch via our contact page here.


Arboles UK - WRAS Approved Material Logo