27/06/2017
Cavity walls built to current building regulations should be a minimum of 440mm thick. Our products comply with the requirements of the Water Regulations, but we are also keen to ease constraints associated with all aspects of building compliance. Our Rear Entry Hose Union Tap Boxes (15mm and 22mm) have been upgraded to come complete with 500mm pipe tails, negating the need for a joint within the cavity wall and thus reducing the risk of costly and inconvenient leaks.
Why Cavity Wall Depth Matters for Plumbing Installations
Modern cavity wall construction, built to current building regulations, creates a specific challenge for external tap installations. When a joint is positioned within the cavity itself, any failure — however minor — can allow water to penetrate the wall structure, leading to damp, mould growth, and potentially significant remedial costs. By extending the pipe tails to 500mm, Arrow Valves has effectively eliminated this risk for the vast majority of standard cavity wall installations.
This change means that the joint sits either inside the building or outside the wall face — never within the cavity — which is both better practice and far easier to inspect and maintain.
Compliance with the Water Supply (Water Fittings) Regulations 1999
All Arrow Valves Hose Union Tap Boxes are designed and manufactured to comply with the Water Supply (Water Fittings) Regulations 1999. External tap installations must include appropriate backflow prevention — typically a double check valve — to protect the mains supply from contamination risk associated with hose connections (Fluid Category 3).
Our ongoing product development programme ensures that every component update not only meets regulatory requirements but actively helps installers achieve compliant, durable installations with less effort on site.
Designed for Installers
At Arrow Valves, product development is driven by feedback from specifiers, plumbing engineers, and installers working across residential and commercial projects. Small refinements — such as extended pipe tails — can make a meaningful difference to installation time, long-term reliability, and compliance confidence. We will continue to update our range as building regulations and best practice evolve.
For technical queries about our Hose Union Tap Box range or any other backflow prevention products, contact the Arrow Valves technical team.
