WATER HYGIENE AND SAFETY £3 million,8


for breaches of health and


safety regulations after deaths resulting from Legionnaires’ disease. It is important to note that Legionella can colonise within both small residential and large commercial and public properties, and thus all water management systems, regardless of size, need to ensure that the risk of Legionella is managed effectively.


Legionella and the law As an employer, property controller, facilities manager, or landlord, you must understand and mitigate against the risks of Legionella. The Health and Safety at Work Act 1974 (HSWA) outlines the duties that you have, while the Management of Health and Safety at Work Regulations (MHSWR) lay out the framework for controlling health and safety at work, and the Control of Substances Hazardous to Health Regulations 2002 (COSHH) detail the actions required to assess, prevent, or control, the risks arising from bacteria like Legionella.


When installing and managing water systems, all duty-holders must adhere to the practical guidance from the Health and Safety Executive’s (2013) Approved Code of Practice, Legionnaires’ disease. The control of legionella bacteria in water systems (L8).2


Across the healthcare sector there are two key pieces of legislation which are underpinned by practical guidelines. The safety principles of healthcare estates and facilities are enshrined in the Health and Social Care Act 2008 (Regulated Activities) Regulations 2014, specifically Regulation 12(2)(h) and Regulation 15 of the Act. Failure to comply with these laws can result in a warning notice, prosecution, and/or the cancellation of a provider’s registration.


Practical information for healthcare premise duty-holders, and best practice guidance underpinning these laws, are laid out in the Health Technical Memorandum 04-01: Safe water in healthcare premises.1


Providing a safe system Providing a safe and effective water system means that, in order to ensure that that system is properly mitigated against the risk of Legionella bacteria, the correct steps should be followed.


These include (but are not limited to):


n Selecting the right equipment and materials.


n Preventing biofouling. n Preventing corrosion. n Considering powered alternatives for soft water, and scale prevention for hard water.


n Finishing off the installation with appropriate cleaning, flushing, and disinfection, according to, for example, BS EN 806 and BS 8558 for hot water systems.


46 Health Estate Journal April 2021


the system. Insufficient flow, along with the right temperature range (20-45˚C), could promote Legionella bacteria in any system. Health Technical Memorandum (HTM) 04-01 states: ‘When control of the microbiological safety of water systems cannot be achieved throughout the system by maintaining temperatures, additional control strategies should be considered to reduce the risk of waterborne infection’. These controls include the movement of water through the system.


Preventing slow-flowing or stagnant water


Flowjet


Across all guidance underpinning the law is the need to prevent any opportunities for slow-flowing water, or water sitting for a period in any system design. The HSE therefore states that: n Checks should be routinely carried out by a competent person, and cleaning done in line with risk assessments.


T-piece


The Flowjet valve ensures continuous flow of water through the bladder of the expansion vessel.


Risk in unvented hot water systems When designing and installing an unvented hot water system, special care should be taken in any property – but particularly in healthcare and care facilities – to guard against Legionella. The primary method of risk reduction is to control the system temperature, and the Health and Safety Executive (HSE) guidance,9


including ACOP L8 and


HSG274 Part 2, state that: n Hot water storage cylinders (calorifiers) should store water at 60˚C or higher.


n Hot water should be distributed at 50˚C or higher (thermostatic mixer valves need to be fitted as close as possible to outlets, where a scald risk is identified).


n Cold water should be stored and distributed at below 20˚C.


The specificity of the guidance10 is driven


by the known effect on bacteria at particular temperatures: n At 20˚C, there is little growth in bacteria. n At 37˚C, temperature is optimum for bacteria growth.


n At 50˚C, it takes several hours to kill Legionella.


n At 60˚C, 90% of bacteria are killed within two minutes.


Control of temperature, however, is not always enough to control bacteria within


n ‘Sentinel’ outlets (furthest and closest to each tank or cylinder) must be identified and checked monthly. Hot water storage cylinder temperatures should be checked every month, and cold water tank temperatures at least every six months.


n As stagnant water favours Legionella growth, all deadlegs/dead ends in pipework should be removed, and infrequently used outlets (including showerheads and taps) should be flushed weekly, with showerheads and hoses cleaned and de-scaled quarterly. Cold water storage tanks need to be cleaned periodically, and all water should be drained from hot water cylinders to check for debris or signs of corrosion.


Expansion vessels and the risk of Legionella


Expansion vessels – otherwise known as expansion tanks or hydraulic


accumulators – should be present in most modern unvented, pressurised hot water systems, in accordance with, and to ensure compliance with, The Water Supply (Water Fittings) Regulations 1999. These unvented or closed water heating systems – with a one-way valve – are particularly vulnerable to increases in pressure, and expansion vessels help protect against these changes. Expansion vessels can prevent damage to components of the installation – as well as maintaining pressure and consistency of heat delivery across the system. Usually, expansion vessels are filled with air or an inert gas (such as nitrogen), and water from the heating system. As the water heats and expands into the vessel, the air in the expansion vessel is able to compress to absorb the added pressure and keep the system stable.


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