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Legionellosis Risk Assessments

The L8 (Fourth edition) Published 2013

This fourth edition of the ACOP and guidance on regulations contains revisions to simplify and clarify the text. The main changes are removing Part 2, the technical guidance, which is now published separately in HSG274 (PART 1, 2 & 3).

Carrying out a legionella risk assessment and ensuring it remains up to date is required under health and safety law and is a key duty when managing the risk of exposure to legionella bacteria.

If the risk assessment concludes there is no reasonably foreseeable risk or the risks are insignificant and are managed properly to comply with the law, the assessment is complete. Although no further action may be required at this stage, existing controls must be maintained. The assessment of risk is an ongoing process and not merely a paper exercise. Dutyholders should arrange to review the assessment regularly and specifically when there is reason to suspect it is no longer valid. An indication of when to review the assessment and what to consider should be recorded and this may result from, eg:

  • a change to the water system or its use;
  • a change to the sue of the building where the system is installed;
  • new information is available about risks or control measures;
  • the results of checks indicating that control measures are no longer effective;
  • changes to key personnel;
  • a case of legionnaires’ disease/legionellosis associated with the system.

Any water system that has the right environmental conditions could potentially be a source for legionella bacteria growth. There is a reasonably foreseeable legionella risk in your water system if:

  • water is stored or re-circulated as part of your system;
  • the water temperature in all or some part of the system may be between 20–45 °C;
  • there are deposits that can support bacterial growth, such as rust, sludge, scale and organic matter;
  • it is possible for water droplets to be produced and, if so, whether they can be dispersed;
  • it is likely that any of your employees, contractors, visitors etc could be exposed to any contaminated water droplets.
“If no such assessment has been carried out; or if there is reason to suspect it is no longer valid, we would advise that this undertaking be instigated as a matter of urgency.”

Legislation – Health and Safety Law – Legionellosis Risk Assessment

Legionnaires’ disease: The control of legionella bacteria in water systems. Approved Code of Practice gives specific information on the health and safety law that applies. In brief, general duties under the Health and Safety at Work etc Act 1974 (the HSW Act)2 extend to risks from legionella bacteria, which may arise from work activities. The Management of Health and Safety at Work Regulations 1999 provide a broad framework for controlling health and safety at work. More specifically, the Control of Substances Hazardous to Health Regulations 2002 (COSHH)3 provide a framework of duties designed to assess, prevent or control the risks from hazardous substances, including biological agents such as legionella, and take suitable precautions

Under general health and safety law, dutyholders, including employers or those in control of premises, must ensure the health and safety of their employees or others who may be affected by their undertaking. They must take suitable precautions to prevent or control the risk of exposure to legionella. They also need to either understand, or appoint somebody competent who knows how to identify and assess sources of risk, manage those risks, prevent or control any risks, keep records and carry out any other legal duties they may have.

The HSE advice is that Dutyholders make reasonable enquiries to satisfy themselves of the competence of contractors in the area of work before they enter into contracts for the treatment, monitoring, and cleaning of the water system, and other aspects of water treatment and control. An illustration of the levels of service to expect from Service Providers can be found in the Code of Conduct administered by the Legionella Control Association (LCA).9
We would recommend using an LCA registered service provider for Legionella Risk Assessments or undertaking tasks relating to Legionella control. A list of approved contractors can be obtained by searching on the LCAs own web site https://www.legionellacontrol.org.uk/directory/ 

BS 8580-1:2019 – Risk Assessments for Legionella Control

In January 2019, BSI Standards Limited released the new, updated ‘BS 8580-1:2019 Water Quality – Risk Assessments for Legionella Control – Code of Practice’. This code of practice applies to risk assessments undertaken on premises, plant and systems and where control measures may have been implemented. First published in 2010, the document provides guidance to duty holders, responsible persons, competent persons and risk assessors on the assessment of risk from man-made water systems, ensuring a suitable and sufficient risk assessment is undertaken.

This revision now aligns the standard with HSE ACoP L8 and its associated guidance documents.

Legionella risk assessment is a legal requirement, making this standard invaluable to anyone responsible for the safe management of water systems, especially within hospitals, the wider healthcare industry, leisure centres and schools.

ph Water Technologies ‘Legionella Risk Assessments’ ensure compliance with current UK regulation and incorporate the requirements of the BS 8580-1:2019.

The BS8580-1:2019 takes on and aligns with the information provided in L8 as part of a general update but there are a number of key changes:

COMPETENCE OF THE RISK ASSESSOR – Section 5.1. The competence of the risk assessor is of ‘paramount importance and should match the complexity of the systems being assessed’. Risk assessors are expected to have no commercial, financial, or other pressures that could compromise their integrity and the risk assessment findings. A risk assessor can decline to undertake or issue a report if insufficient information has been provided to assess risk successfully; reports can be issued in draft if needed. It is the responsibility of the duty holder to check the competence and independence of the risk assessor and ensure that all information available and access is provided to all water systems to allow the risk assessment to be completed.

RISK ASSESSMENT REPORTING – Section 9 has been re-written to further emphasise that risk assessments must be clear, easy to read, free from superfluous information and focus on the systems that have been assessed. BS 8580 states that remedial actions should be high priority, where management roles of the systems being assessed are not being fulfilled. The preparation of a written scheme is not part of the risk assessing process. BS 8580 outlines that a risk assessor must confirm the presence and relevance of the written scheme in place and make recommendations for improvement, but the risk assessment should not include a written scheme. If a client requires one, it must be commissioned separately.

RISK REVIEW & RE-ASSESSMENT – Section 10 has been made clearer outlining that a policy of planned reassessments must be in place – Reassessments must be a new report, and not simply an adaptation of previous reports.

EVALUATION OF RISK – Section 8. A risk assessors must assess if the residual risk is as low as reasonably practicable (ALARP). Control measures that have been put in place must be regularly reviewed to ensure they are not ‘grossly disproportionate’ and unjustified.

ANNEXES – These have been revised and updated to reflect content in HSG274 and HTM04-01. There is more detailed and clearer guidance within Annexe B for Hot & Cold-Water Systems. Annexe C for Open Evaporative Cooling Systems and Annex D for Spa Pools have been completely re-written. In each of these annexes, the competence of the risk assessor is stressed as fundamental to the risk assessing process. Annexe E on Other Systems is more detailed and contains new information on humidifiers and thermal processing in the food industry.

BS 8580 has been renamed to BS 8580-1 as there is a plan to provide a British Standard for Pseudomonas aeruginosa risk assessments, undertaken in high-risk healthcare environments, and this is expected to be named BS 8580-2.

For more information please visit our downloads page, HSE Legionnaires’ Technical guidance, or email us.

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Disinfections

The cleanliness of the system must be maintained as legionella bacteria are more likely to grow in a system fouled with deposits.

Any new water system will require at least flushing and disinfection before being brought into use and the building commissioning process should take into account the size and complexity of the water system.

The risk from exposure to legionella should be controlled by keeping the water system and water in it clean and free from nutrients, including those arising from contamination and corrosion; and maintaining its cleanliness. Hardness scale may also trap nutrients, encouraging biofilm formation and so form a barrier to disinfectants.

Where necessary, hot and cold water services should be cleaned, flushed and disinfected in the following situations, as specified in BS 8558:2011:

  • On completion of a new water installation or refurbishment of a hot and cold water system;
  • On installation of new components, especially those which have been pressure tested using water by the manufacturer (see the manufacturer’s instructions);
  • Where the hot and cold water is not used for a prolonged period and has not been flushed as recommended or the control measures have not been effective for a prolonged period. For example, this could be as little as two or three weeks, but will depend on the ambient temperature, condition of the water system, potential for exposure to aerosols and the susceptibility of users considered in a specific risk assessment;
  • On routine inspection of the water storage tanks, where there is evidence of significant contamination or stagnation;
  • If the system or part of it has been substantially altered or entered for maintenance purposes that may introduce contamination;
  • Following water sampling results that indicate evidence of microbial contamination of the water system
  • During, or following an outbreak or suspected outbreak of legionellosis linked to the system;
  • Or where indicated by the risk assessment.

Ph Water Technologies can provide cleaning and disinfection services in accordance with ACoP L8 and the latest British standards. Our final report will include pre and post clean photographs of the works undertaken.

Disinfections of incoming mains water supply

If your supply is of 50mm internal diameter and above:

Under the Water Supply (water fittings) Regulations 1999 (SI 1999, 1148), you will be required to disinfect your underground pipe work prior to connection.

The disinfection must be carried out to ‘BS 8558:2011’. This is to ensure there is no detriment to public health.

For further details and clarification, please refer to section G13.1 of the Guidance Notes to S1 1999, 1148 and clause 3.1.10 of BS 8558:2011.

New supplies should be swabbed, flushed, filled with chlorinated water not less than 50mg/l and allowed to stand for 1 hour, following which the chlorinated water should be flushed out, the pipe refilled, and a sample taken.

The pipework must be disinfected with a ‘hypochlorite’ solution’.

The following must be submitted to our office prior to the connection being made:

  • A disinfection certificate
  • A method statement of the disinfection carried out
  • The sample results

The ‘certificate’ must indicate the name of the company performing the disinfection, date of disinfection, confirmation that the pipe has been swabbed and flushed prior to disinfection, a ‘hypochlorite’ solution has been used, the chlorine level of the source water, the chlorine level after dosing, the contact time, the chlorine level after contact, and the chlorine level after flushing. It must also detail the onsite test for appearance, odour and taste.

The certificate must clearly state that the disinfection has been carried out in accordance with BS 8558:2011.

The ‘method statement’ must indicate the details of the disinfection carried out, the diameter and length of pipe disinfected, the source of the water used, the sample location point, and a diagram.

The ‘sample results’ must include E-coli, total coliforms, turbidity, and plate counts taken at both 22°C and 37°C. The post flush chlorine level must also be confirmed by laboratory analysis.

The sample results must be from a ‘UKAS’ accredited laboratory.

It is also the customer’s responsibility to ensure that the designated disinfection company is aware of Thames Water’s requirements.

If this procedure is not met the relevent “Utility Provider” have a right to refuse the final connection, and the pipework must be re-disinfected to meet their requirements. They will not begin the connection process until they have received these documents complete with all information.

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Acid Descaling

Limescale causes a significant increase in energy input to the boiler to meet the same heat demand it will also insulate the water from the heat source and impair performance and heat transfer. Build up of scale and fluctuating temperatures encourages the growth of bacteria including Legionella which could also pose a serious risk to users of the system

Hot water systems present the greatest risk in environments which allow the proliferation of legionella. In order to comply with section 182 of HSG274 Where inspection hatches have been installed draining the calorifier and checking for debris in the base of the vessel should be carried out annually. The calorifier should then be cleaned if considered necessary.

PH Water can provide bespoke acid descaling solutions that include complete online descaling where hard water has contributed to heavy scale formation within system pipework

Calorifiers will often pose a higher risk of Legionella growth. This is due to high levels of scale and nutrients in a part of the system where water is at a temperature favourable to the growth of Legionella.

In order to comply with the HSE HSG274 Part 2 you are required to inspect your calorifiers annually by removing the inspection hatch or using a boroscope and clean by draining the vessel. The frequency of inspection and cleaning should be subject to the findings and increased or decreased based on conditions recorded.

For free advice on legionela prevention and control please contact us.

What could be lurking in yours?
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Borescope Inspections

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Carrying out visual inspection of plant is often required in order to comply with current legislation and is also a great tool to determine the effectiveness of a water treatment program.

By using a borescope ph Water & Air Technologies can provide you with a convenient way to visually determine if your water treatment program is preventing scale formation, copper corrosion and biological fouling.

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Monitoring & Maintenance of Domestic Water Systems

Cleanliness, water quality and microbiological control are essential factors in the safe operation of engineered water systems, and maintaining good domestic system water quality. As specialists in the field of water hygiene ph Water Technologies Ltd provide not only traditional methods of monitoring, cleaning, disinfection and refurbishment of domestic and process water systems, but also innovative control systems. All systems and practices are designed to meet specific site requirements for industrial, commercial, leisure and healthcare premises. All working methods and control systems comply with the latest Codes of Practice and specifications.

Typically the systems to be considered are:

  • Cold water storage tanks
  • Cooling towers
  • Evaporative condensers
  • Domestic water tanks/systems.
  • Calorifiers and water heaters
  • Air handling units
  • System pipework
Legionella bacteria are common in natural water courses such as rivers and ponds. Since legionella are widespread in the environment, they may contaminate and grow in other water systems such as cooling towers and hot and cold water services. They survive low temperatures and thrive at temperatures between 20°C- 45°C if the conditions are right, e.g. if a supply of nutrients is present such as rust, sludge, scale, algae and other bacteria. They are killed by high temperatures. It is therefore important to control the risks by introducing measures outlined in the Approved Code of Practice & guidance document Legionnaires’ disease – The Control of Legionella Bacteria in Water Systems (L8).
As an employer or a person in control of the premises (eg a landlord), under general health and safety law, you have to consider the risks from legionella that may affect your staff or members of the public and take suitable precautions.
There have recently been a number of high profile cases of Legionnaires disease. All businesses have an obligation to take the correct measures to protect their staff, customers and the public against the risk of Legionnaires disease. The Code of Practice and Guidance called L8 was designed to help businesses meet their legal obligations.
Samples should be sufficient in number to be fully representative of the distribution system, sub-branches, tanks and cisterns as well as the condition to be evaluated, e.g. completion of a cleaning process, efficacy of distribution of disinfectant; and taken at a frequency which is representative of the time series to be demonstrated, e.g. taking into account the growth rate of the organism when designing the monitoring scheme to check for potential microbiological colonization.

Sampling and Monitoring Quality Assurance

Regular sampling practice audits should be carried out to ensure that a responsible person can verify the cleaning process or monitoring programme as part of a building water safety plan (see the WHO’s Water safety in buildings [28]). Water quality sampling practice should be audited in accordance with BS 8550

HSG274 & BS8558 Guidelines for Cold Water Storage Tanks

Regular inspections of the tank and microbiological sampling are specific requirements of HSG 274 and BS8558 (previously BS6700) to remain compliant with the HSE’s ACoP L8.

To help you understand the guidelines ph Water have devised the table below:

*Potable cold water storage tanks are those which feed drinking water outlets
** Annually or more frequent if inspection deems necessary

This table should be used as a guide only. If you are responsible for the health and safety of a water system you should carry out a risk assessment to determine the frequency of any controls or seek professional advice.

The perceived risk level should determine the frequency of sampling and locations. We would recommend that (as a minimum) samples are collected on a six monthly basis and the locations include: incoming main; Cisterns; Calorifiers; showers, sentinel Hot and sentinel Cold water outlets.

For more information and technical guidance, please visit our downloads page.

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