WATER HYGIENE AND SAFETY
Legionella spp. is commonly found in water systems. However, the issue of concern is the avoidance of the conditions necessary for the growth and proliferation of the organism to levels at which it poses a significant risk. These conditions include: n Dirty water systems – the presence of sludge, scale, rust, algae, and organic matter (nutrients for growth and environments to live within);
n Water temperatures in the range 20˚C to 45˚C – Legionella spp. multiplies within this range. It is killed rapidly at water temperatures above 60˚C. Below 20˚C it stays dormant, but will grow if the temperature is raised and other conditions are favourable;
n Stagnation of water, such as within deadlegs or stagnant vessels;
n Poor design, operation, and maintenance, of the water system.
Legal requirements
On 23 November 2000 the Health and Safety Commission approved, with the consent of the Secretary of State for the Environment – under Section 16 of the Health and Safety at Work etc. Act 1974 – an Approved Code of Practice (ACoP) entitled Legionnaires’ Disease – The control of Legionella bacteria in water systems (also known as ‘L8’). On 8 January 2001 the ACoP came into force, giving practical advice with respect to the requirements as regards risks from legionellosis under the Health and Safety etc Act 1974 and the Control of Substances Hazardous to Health Regulations 2002. Both the ACoP (L8) and HTM 04-01 have been updated more recently, and guidance in the form of HSG 274 introduced, which adds more detail on important elements such as risk assessment, the scheme of control, and the roles of the Water Safety Group. The ACoP (L8) identifies the following essential duties: n A person should be appointed to be managerially responsible and to provide supervision for the implementation of the precautions;
n A thorough assessment should be carried out to identify and assess the risk of legionellosis from work activities, water sources, and any necessary precautions;
n An action plan should be produced for the remedial work necessary to minimise the risks identified;
n Precautions to manage and control risk should be implemented;
n Adequate records should be maintained;
Principal strategies
The principal strategies for the control of water hygiene and Legionella spp. include operating the water system at the appropriate temperatures to prevent the proliferation of Legionella spp.
60 Health Estate Journal January 2019 0 Date (2014) Figure 1: Increasing Legionella spp. positive sample results.
Delegates on one of Eastwood Park’s Water Hygiene training courses.
In the healthcare environment. This means maintaining hot water storage temperatures above 60˚C, and distribution and return temperatures at a minimum of 50˚C, and preferably 55˚C. Cold water should, meanwhile, be maintained at below 20˚C. Avoiding stagnation and temperature stratification are both key, while little used outlets should be flushed regularly or removed, so that there are no deadlegs. Water systems should also be kept clean and contamination-free.
Against this backdrop, appropriate design, sizing, layout, construction, commissioning, and ongoing operation and monitoring of the water services to avoid conditions which will promote or
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encourage microbial proliferation (e.g. deadlegs, non-approved materials, poor temperature performance etc.) are all vital. Materials and fittings acceptable for use in the water system are listed in the directory published by the Water Research Centre. Low corrosion materials – for example copper – should be used where practicable, and flexible hoses avoided.
Thorough risk assessment To understand a healthcare facility’s water systems a thorough risk assessment must be completed. This should culminate in the development of an action plan, and a formal written scheme specific to the system. The understanding of both of these requirements has been clarified within the recently improved guidance in HSG274 and HTM 04-01. This plan should consider the factors which influence the growth and proliferation of the bacterium, i.e. design, condition, operation, performance, vulnerability, and exposure. The risk assessment will be used to produce recommendations for the control of Legionella spp., in the form of a Written Scheme of Control and action plan, with prioritised opportunities for improvement (OFI).
Key elements of successful legionellosis risk management include: n Operational – consisting of operational actions that those responsible for the water services should ensure are carried out;
n Remedial works – typically engineering modifications to water systems, in a prioritised programme, managed by those responsible for the water services;
n Systematic risk management – broader recommendations made to those responsible for the water services, dealing with issues such as training, review, etc.
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