What is BG04?

BG04, known as Guidance on Industrial Boiler Water Treatment, was developed by the Combustion Engineering Association (CEA).

It sets out the responsibilities of owners, managers and operators to ensure that water quality is consistently monitored, treated and maintained to prevent damage and safety risks. This includes having effective testing regimes, using the correct treatment chemicals, keeping dosing equipment in good working order and making sure operators are trained and competent to carry out daily checks and corrective actions. By defining clear lines of accountability, BG04 ensures that water treatment is recognised as a vital part of boiler safety and efficiency rather than an afterthought.

What does BG04 cover?

The guidance gives clear, practical recommendations on:

  • Water treatment for both steam and hot water boilers (including generators)
  • Preventing scale formation and controlling corrosion
  • Correct use of dosing systems and treatment chemicals
  • Monitoring and testing regimes for ongoing compliance
  • Legal frameworks and operator responsibilities
  • Carrying out risk assessments for water treatment systems
  • Record keeping to support safe operation and audits

Why BG04 matters

BG04 is not legislation, but it is recognised as introductory guidance for boiler water treatment in the UK. Following it helps operators demonstrate compliance with PSSR and other health and safety requirements.

Without proper water treatment, boiler systems can become unsafe, inefficient and costly to repair. BG04 gives operators a proven framework to reduce these risks and extend equipment life.

Download the latest version of BG04

The current edition of BG04, Edition 4, was published in March 2019 and is available to download from the CEA’s official document store.

At Dunphy, we help customers manage safe and efficient boiler operations, including support for water treatment which is included within our BOAS courses. Get in touch with our team today to find out more.

For more information, see our blogs on BG01: what’s new for steam boilers regulations? and BG02: what hot water boiler operators need to know? & BG03: safe operation of blowdown systems for industrial steam boilers.