BSRIA Water Treatment for Closed Heating and Cooling Systems BG 50/2021
![]() |
Contents |
[edit] Introduction
In November 2021, BSRIA published the second edition of its Water Treatment for Closed Heating and Cooling Systems (BG 50/2021). This updated version supersedes BG 50/2013 and is available to purchase from the BSRIA Bookshop. It is also being offered to BSRIA members as a free download.
[edit] Background
Water treatment is essential in closed heating and cooling systems. Without it, there is far greater risk of biological fouling (also known as biofouling), corrosion and scale. These problems can lead to poor performance, system failures and costly remedial works.
BSRIA first published guidance on water treatment in 1993. A major overhaul of this older guide, including a change of scope, occurred in 2013, at which point it was renumbered and renamed: BG 50/2013 Water Treatment for Closed Heating and Cooling Systems.
This guide became widely used in the industry; however, it became clear that it needed an update to bring it in line with current technology and practices and updated standards and guidance. In particular, this revised edition is consistent with Pre-Commission Cleaning of Pipework Systems (BG 29/2021), which was published in February 2021.
The technical content of the publication was written by Dr Pamela Simpson with the help of a steering group, including representatives from the British Chemicals Association (BCA), the Closed Systems Control Association (CSCA), the Industrial and Commercial Heating Equipment Association (ICOM), the Institute of Corrosion (ICorr), the Institute of Workplace and Facilities Management (IWFM) and the Water Management Society (WMSoc).
[edit] What does BG 50/2021 cover?
At present, chemical water treatment is the dominant water treatment technique for closed heating and cooling systems in the UK. Therefore, this technique is covered in depth in the guide. Other techniques are also available, and a number of these are covered in the guide, including:
- Pre-treatment of fill water.
- Removal of dissolved gases.
- pH management.
- Solids removal and filtration.
- Galvanic anode cathodic protection/electrochemistry.
- Bacteria and biofouling inhibition by biocides.
Expanded guidance has been provided on the roles and responsibilities of those typically involved with water treatment in closed systems: planners of water treatment programmes, maintenance water treatment specialists, day-to-day system operators, building owner/operators and remedial cleaning specialists.
The suggested water quality analyses and guidelines have been updated, including the addition of corrosion rates. Additional guidance has been provided on corrosion monitoring and on-site testing, including the use of test kits.
This article originally appeared on the BSRIA website under the headline, 'BSRIA launches update to Water Treatment for Closed Heating and Cooling Systems'. It was published in November 2021.
--BSRIA
[edit] Related articles on Designing Buildings
- Biological fouling.
- BSRIA articles on Designing Buildings Wiki.
- Chilled water.
- Closed system water treatment: BG 50 & VDI 2035.
- Commissioning building systems.
- Heating ventilation and air conditioning.
- Pipework.
- Training for pre-commissioning cleaning of pipework systems.
- Water treatment.
[edit] External resources
Featured articles and news
Combating burnout.
The 5 elements of seiri, seiton, seiso, seiketsu and shitsuke.
Shading for housing, a design guide
A look back at embedding a new culture of shading.
The Architectural Technology Awards
The AT Awards 2025 are open for entries!
ECA Blueprint for Electrification
The 'mosaic of interconnected challenges' and how to deliver the UK’s Transition to Clean Power.
Grenfell Tower Principal Contractor Award notice
Tower repair and maintenance contractor announced as demolition contractor.
Passivhaus social homes benefit from heat pump service
Sixteen new homes designed and built to achieve Passivhaus constructed in Dumfries & Galloway.
CABE Publishes Results of 2025 Building Control Survey
Concern over lack of understanding of how roles have changed since the introduction of the BSA 2022.
British Architectural Sculpture 1851-1951
A rich heritage of decorative and figurative sculpture. Book review.
A programme to tackle the lack of diversity.
Independent Building Control review panel
Five members of the newly established, Grenfell Tower Inquiry recommended, panel appointed.
Welsh Recharging Electrical Skills Charter progresses
ECA progressing on the ‘asks’ of the Recharging Electrical Skills Charter at the Senedd in Wales.
A brief history from 1890s to 2020s.
CIOB and CORBON combine forces
To elevate professional standards in Nigeria’s construction industry.
Amendment to the GB Energy Bill welcomed by ECA
Move prevents nationally-owned energy company from investing in solar panels produced by modern slavery.
Gregor Harvie argues that AI is state-sanctioned theft of IP.
Experimental AI housing target help for councils
Experimental AI could help councils meet housing targets by digitising records.