What is BS-8558
Last updated 28/05/26 | Updated by Helen – H2O Comply
What is BS-8558?
BS-8558 is the British standard for the design, installation, and maintenance of services supplying water within buildings. It was developed to provide complementary guidance to the BS EN 806 series of standards, and together these documents set out best practice for the design, installation, alteration, testing, operation, and maintenance of hot and cold water services in buildings.
In plain terms, BS-8558 is the practical guidance that helps you keep the water systems in your building safe, clean, and working as they should.
If you are a duty holder, this matters to you directly. Whether you own, manage, or are responsible for a property, you have a legal duty to make sure the water supply is safe for the people who use it. BS-8558 gives you a recognised framework for doing exactly that. It covers everything from how a system should be installed in the first place, through to the ongoing checks, cleaning, and testing needed to keep it in good order over its lifetime.
Following BS 8558 does more than tick a box
It helps you reduce the risk of waterborne issues such as Legionella, protect the people in your building, and demonstrate that you have taken reasonable steps to manage water safety should you ever need to show it
Reduce risk
Lowers the chance of waterborne issues such as Legionella in your water systems.
Protect people
Keeps the water safe for everyone who uses your building, including staff, tenants and visitors.
Show diligence
Demonstrates you took reasonable steps, should you ever need to prove it.
Part of a joined-up approach to water hygiene
For most duty holders, BS 8558 sits alongside your wider legal obligations.
Health and Safety at Work Act
Your overarching legal duty to keep people safe.
ACoP L8 guidance
The approved code of practice for controlling Legionella in water systems.
Who is BS-8558 relevant for?
The standard should be applied by:-
- Anyone involved in the design, installation, testing, operation, and maintenance of services (businesses with water storage facilities)
- Water companies
- Product manufacturers
- Installers of water supply services in the UK
Why should you use BS-8558
The BS-8558 Standard is an effective tool in the safe maintenance of water systems for companies and domestic buildings.
It provides UK guidelines for the water supply services industry on all aspects of sampling and monitoring of hot and cold water services.
It also gives guidance on underground pipework within the curtilage of a building.
BS 8558 & Legionella
BS8558 recognises the need to control Legionella bacteria in onsite domestic wastewater systems and provides guidance on how this can be achieved.
It is important to note that while BS 8558 does not specifically cover rainwater harvesting systems, these are often included as part of onsite water management systems. As such, it is important to ensure that any rainwater harvesting system is designed, installed and maintained in accordance with BS 8558.
Tank Cleaning and BS 8558
It is a requirement of BS 8558 that all onsite domestic wastewater treatment systems must be cleaned and serviced at least once a year by a suitably qualified professional.
Water tank cleaning is an important part of maintaining an onsite water system. It helps to remove any build-up o and ensure water is safe for consumption.
A water tank cleaning company will have the necessary expertise and equipment to carry out this work safely and effectively. They will also be able to provide advice on any other maintenance that may be required to keep your system operating correctly.
You will also be provided with a chlorination certificate, this document will contain detailed information about the chlorination procedure, including the date and time of the chlorination, the type and concentration of disinfectant used, and the duration of the chlorination process.
Water Testing and BS 8558
If you own or operate a business that uses water, then you need to make sure that you are in compliance with the latest water regulations.
You can do this by arranging for a legionella water testing company to check your water quality. Samples will be taken from your water tanks and sent for laboratory testing.
H2O Comply Tank cleaning and Water sampling are undertaken in line with BS8558 Guidance, if you need help with any aspect of your water quality standards, tank cleaning or water testing please get in touch with a member of the team for more information.
