Category 5 Tanks 

Cat 5 Tanks, also known as Type AB Airgap Break Tanks (Category 5 Backflow Prevention)

Nicholson Plastics are a water storage & regulations experts, we provide a full range of water storage solutions that provide backflow protection for Fluid Category 5 risks.

Category 5 risks are fluids that pose a serious health risk due to the concentration of pathogenic organisms or extremely toxic or radioactive elements present with them including any fluid which contains; faecal material or other human waste: butchery or other animal waste: or pathogens from any other source.


Uses for Category 5 tanks:

  • Urinals
  • Laboratories
  • Drain cleaning plants
  • Industrial cisterns and bin
  • Chemical cleaners/contractors
  • Butchery and meat trades
  • Bedpan washers
  • Hospital dialysis machines
  • Vegetable washing
  • Laboratories
  • Dish washing machines in healthcare premises

Water Supply (Water Fittings) Regulations 1999 in England and Wales and Scottish Water Byelaws state the installation of cold water storage tanks, connected to the public water supply must comply with the UK water fitting regulations. In order to meet these requirements Category 5 Break Tanks must be used.

AB Airgap & Overflow

A non-mechanical backflow prevention arrangement of water fittings complying with Type AA, except that the air gap is the vertical distance from the lowest point of the discharge orifice which discharges into the receptacle, to the critical water level of the rectangular weir overflow. WRAS Type AB – Air gap

Read Guide to the UK Water Supply Regulations