GUIDANCE · OCTOBER 2026
If you’ve been told water mist is “no longer accepted”, or that the standard behind it has been scrapped, here’s what actually happened — in plain English, with sources you can check.
Illustrative image.
What happened
On 7 July 2025, BSI withdrew BS 8458:2015, the code of practice for the design and installation of residential and domestic watermist systems.
BS EN 14972-17:2025, a European fire-test protocol for watermist systems in residential occupancies, now takes its place as the current BSI standard. It’s a real change — but a narrower one than some headlines suggest.
What it means
A withdrawn standard is one BSI no longer maintains. It doesn’t ban the technology it describes, and it doesn’t retrospectively invalidate systems that were designed and installed to it.
What changes is the benchmark going forward. BS EN 14972-17 is a fire-test protocol, so the emphasis shifts towards systems and components with evidence of performance in standardised residential fire tests.
In Scotland
In Scotland the question that matters is what the building standards guidance cites, because that’s what your verifier works from. The guidance for Standard 2.15 in the Scottish technical handbooks has continued to name BS 8458:2015 for watermist design, alongside BS 8663-1 for watermist nozzles.
The handbooks are revised regularly — the current domestic edition applies to building warrants submitted from 6 April 2026 — so every design should be checked against the edition in force when your warrant goes in. We do that as part of every design.
Conflicting claims
Some firms have used the withdrawal to claim water mist is no longer accepted by building control. That isn’t what a withdrawal means, and it isn’t what the Scottish guidance says.
Acceptance of any suppression system on a warrant is a matter for your verifier, based on the design case put in front of them. That’s why the documentation matters as much as the hardware. If someone tells you otherwise, ask for their source.
What to do
If you already have a system designed to BS 8458, nothing changes.
If you’re planning one now, it should be designed to the standard cited in the handbook edition that applies to your warrant, using components with the test evidence your verifier will expect. That’s how we work — and if you’re not sure where your project stands, send us the details and we’ll give you a straight answer.
Residential and domestic water mist systems, designed to the standard Scotland’s building standards cite.
Fitted and commissioned by qualified plumbers, backed by 19 years of frontline firefighting.
Design and consultancy for architects, builders and developers.
Tell us about the building and we’ll tell you which standard applies and what your verifier will expect to see.
