BS 8489 is the British Standard series for industrial and commercial watermist systems, spelled as one word the way BSI spells it (BSI). Its residential counterpart, BS 8458, was withdrawn in July 2025, and the European fire test protocol for residential occupancies replaced it in the UK. A specification written before mid-2025 may therefore cite a withdrawn standard.
What does BS 8489 cover?
BSI lists five parts in the series:
- Part 1, code of practice for design and installation. Published on 31 May 2016 and current, it superseded DD 8489-1:2011 (BSI).
- Part 4, fire performance tests and requirements for local applications involving flammable liquid fires. Current since 31 May 2016 (BSI).
- Part 5, fire performance tests and requirements for the protection of combustion turbines and machinery spaces with volumes up to and including 80 m³.
- Part 6, fire performance tests and requirements for the protection of industrial oil cookers.
- Part 7, tests and requirements for the protection of low hazard occupancies. Withdrawn on 8 July 2025 (BSI).
The series pairs a code of practice for design and installation with fire tests for named applications. That is the same split found in the US and European frameworks: NFPA 750 requires a system designed to a listing based on fire tests (NFPA 750 explained), and EN 14972 carries application-specific fire test protocols (EN 14972 explained).
What happened to BS 8458?
BS 8458:2015, Fixed fire protection systems — Residential and domestic watermist systems — Code of practice for design and installation, was published on 30 November 2015 and withdrawn on 7 July 2025 (BSI).
BS EN 14972-17:2025, published on 31 July 2025, is "the UK implementation of EN 14972-17:2025" and states that it supersedes BS 8458:2015 (BSI). It specifies fire testing requirements for water mist systems protecting domestic and residential occupancies up to a maximum ceiling height of 5.5 m, with examples that include houses, apartment buildings, blocks of flats and care homes. Its European foreword set January 2026 as the latest date for withdrawing conflicting national standards.
For anyone holding an older residential specification, the reference has moved from a British code of practice to a European fire test protocol.
Where does BS EN 14972 fit?
European Standards are published in the UK as BS EN documents, and BSI's membership of CEN and CENELEC continued after Brexit, confirmed from 1 January 2022 (BSI). BS EN 14972-1:2020+A1:2025, the design, installation, inspection and maintenance part of the European water mist series, was published on 31 August 2025 with a revised national annex and national foreword (BSI).
BSI lists BS 8489-1:2016 as current alongside it. They are different documents, so a specification that names both should say which governs where they differ, and which fire test evidence the design relies on: a BS 8489 test part, an EN 14972 protocol or an LPCB standard.
Does Approved Document B accept water mist?
It does not name it. Neither volume of Approved Document B — dwellings, and buildings other than dwellings — mentions water mist, BS 8489 or BS 8458 (Volume 1, Volume 2).
What both volumes reproduce is Requirement B3(3) of the Building Regulations: where reasonably necessary to inhibit the spread of fire within a building, the measures taken must comprise either or both of sub-division with fire-resisting construction and the installation of suitable automatic fire suppression systems. Whether a water mist system is "suitable" is a question of evidence for the building in question.
What does LPCB approval involve?
LPS 1283, Requirements and test methods for the approval of watermist systems for use in commercial low hazard occupancies, is a Loss Prevention Standard owned by BRE Global (LPS 1283). Issue 1.1, dated January 2014, specifies the requirements and test methods for LPCB approval of fixed watermist systems in commercial low hazard occupancies within buildings. It is underpinned by DD 8489 Part 1 and DD 8489 Part 7:2011 and adds requirements of its own.
The standard says installers of LPS 1283 approved systems should be approved to LPS 1284, to verify their competence for design, installation and maintenance. LPCB's Red Book, its list of approved products and services, has a dedicated part for watermist systems (Red Book Part 5).
What should a UK water mist specification include?
- the design standard, BS 8489-1 or BS EN 14972-1, and which governs where they differ;
- the fire test evidence for the occupancy: the relevant BS 8489 part, an EN 14972 protocol, or LPS 1283 for commercial low hazard occupancies;
- for homes, flats and care homes, evidence to BS EN 14972-17 rather than a reference to the withdrawn BS 8458;
- the installer's competence scheme, such as LPS 1284 where the LPCB route is used;
- the evidence the building control body will accept, agreed early rather than at completion.
Where Mistelix stands
Mistelix designs its water mist systems with reference to NFPA 750. Full-scale fire testing, FM Approval and UL listing are planned. Our live status against every standard we work to is in our approvals ledger.
Sources: BSI, BS 8489 series, BS 8489-1:2016, BS 8489-4:2016, BS 8489-7:2016, BS 8458:2015, BS EN 14972-17:2025, BS EN 14972-1:2020+A1:2025 and CEN and CENELEC membership; GOV.UK, Approved Document B Volume 1 and Volume 2; BRE Global, LPS 1283 Issue 1.1 and LPCB Red Book Part 5.