What is a Type AUK 3 tap gap?

A Type AUK 3 tap gap is suitable for high risk installations (fluid category 5 or lower). It is a specific minimum distance between the lowest point of a tap spout, shower head or other fitting and the spillover level of the high risk appliance or receptable it supplies.

A Type AUK 3 tap gap is rated by the Regulators as suitable backflow protection against the highest level of contamination, fluid category 5 but for back siphonage only.

The requirements for a Type AUK3 tap gap are :

1. The tap gap is measured vertically from the lowest point of the outlet, which includes any aerator or flow straightener fitted, and the spillover level of whatever receptacle it supplies.

2. The gap required must be not less than 20 mm or twice the diameter of the inlet pipe supplying the installation whichever is the greater.

Where an AUK3 tap gap cannot be maintained, for example where the tap gap is compromised as a result of:-

• the tap being lowered in any way;

• adjustment to the spout which reduces the distance between the tap outlet and spillover level of the sink; or

• the operation of a pull out hose attachment

An alternative form of fluid category 5 backflow protection is required.