WATER SYSTEM SAFETY


At-risk locations Legionella is most likely to be a serious risk in large premises with complex water systems – it is rarely an issue in small and domestic settings. Public buildings such as hospitals are more typically at risk of harbouring Legionella, and potentially producing an outbreak of Legionnaires’ disease.


The risk is currently heightened in buildings that have been closed due to the coronavirus pandemic, or premises that have had reduced occupancy over this period. Water stagnation may arise in closed and under-used buildings, so the Legionnaires’ disease risk is increased.


A crucial duty of care


In the past, Legionnaires’ disease has struck with tragic consequences in the UK and around the world, leading to tough legislation and regulation to protect against further outbreaks. Today in the UK the duty of care and those responsible for it are clearly defined by the Health & Safety Executive (HSE).


If you hold one of these positions, you are bound by law to fulfil certain obligations: n You must identify and assess sources of risk.


n You should prepare a scheme to prevent or control the risk.


n You must implement and effectively manage monitoring precautions.


n You should keep complete records of precautions.


n You must appoint a competent person with sufficient authority and knowledge of the installation to help take the measures needed to comply with the law.


The person or team appointed to identify risks and implement solutions to control Legionella will need to have the appropriate authority to make sure that all measures are effective and applied in a timely manner. They will also need to be competent in managing water systems in relation to the risks of pathogens, and to have a thorough knowledge of the system or systems in question.


Essential reading for duty-holders – ACoP guidelines


This article constitutes an overview of some of the issues surrounding Legionella. The Health & Safety Executive’s Approved Code of Practice (ACoP) L8, Legionnaires’ disease: The control of legionella bacteria in water systems, offers practical advice and specific guidance on the control of Legionella bacteria in water systems. Additionally, the ACoP L8 is supported by the Health & Safety Executive’s HSG274, Legionnaires’ disease: Technical guidance document, which provides additional guidance covering the operation and management of the following risk systems,


68 Health Estate Journal November 2021


Accurate monitoring of the temperature of the the hospital water supply is a key element of patient and staff safety.


evaporative cooling systems, hot and cold water systems, and other risk systems. Identifying risks and assessing their sources, preparing a scheme to prevent or control risk, implementing, managing, and monitoring precautions, keeping records, and appointing a competent manager, should all be performed in accordance with the HSE’s guidance.


Practical actions for preventing and controlling the risk There are a number of ways that an existing water system can be improved and made less likely to develop Legionella or other bacterial contamination.


Preventing water from stagnating If water can be kept moving throughout the system, Legionella and other bacteria are much less likely to become established. It is good practice to keep pipe runs as short and direct as possible, and to remove any redundant parts of the system – particularly ‘deadlegs’ in pipework where water can remain permanently still. This is an issue that should be addressed whenever an area is taken out of use.


Any parts of the system infrequently used should have outlets regularly opened; allowing water to flush through once a week can significantly reduce the risk of bacteria becoming established. DVS has developed spouts and sensors which can be programmed to automatically purge water to help reduce the risk of bacterial build-up. This can help guard against infection and reduce maintenance costs. These units can be controlled by handheld programmers which allow easy adjustment of run-on time, range, and purge. Real-time data can also be accessed via the unit’s USB port.


Use appropriate materials Only fittings, materials, and appliances approved for use in the UK water supply system – as defined by the Water Regulations Advisory Scheme – should be included in water systems. Using unapproved materials runs the risk of harbouring bacteria and other microorganisms, or inadvertently providing organic materials which can feed pathogens and help them to become established. Antimicrobial materials and coatings can also be incorporated to water-dispensing products. These provide fast, effective antimicrobial protection for the lifetime of the product. The range of DVS products – these include valves, showerheads and spouts – offers an extra level of protection using Biomaster silver ion technology, which is an integral part of the product.


Keep the system’s water clean In smaller systems, it may be possible to flush fresh water through every part on a regular basis, but more complex and bigger networks will require water treatment to control the growth of microorganisms within acceptable limits.


Record risk assessments, maintenance, and repair work In organisations with five or more employees, the findings of any risk assessment of water systems must be recorded, along with details of maintenance and repair work. These must be kept for two years. Records relating to monitoring and inspection should be retained for five years. It is also good practice to maintain records of any relevant employee training and the activities of any external contractors.


Operational measures Solutions ensuring that the risk of Legionella is prevented or effectively controlled are centred on three important areas: n Water temperature control. n Physical measures – such as regular movement of water in hot and cold water systems, and flushing of outlets and point-of-use (POU) filters. n Biocide treatments.


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