Legionella Risk Assessment and Water Hygiene Management

Legionella in Brief

Assess legionella risk in water systems under L8 and HSG274
Implement a written scheme of control with temperature monitoring and cleaning
Keep records of monitoring, inspection and remedial action

Managing Legionella Risk

Legionella bacteria can cause Legionnaires' disease - a potentially fatal form of pneumonia contracted by inhaling water droplets containing the bacteria. Anyone responsible for premises that have a water system has a duty to assess and manage the risk of Legionella.

Legionella risk is higher in certain conditions: water temperatures between 20 and 45 degrees Celsius, where water is stored or stagnant, and where there is any organic matter present that provides nutrients for the bacteria to grow. The risk of infection increases when water is aerosolised into breathable droplets - which can occur through showers, taps, spray nozzles, humidifiers, cooling towers and decorative fountains.

In most typical workplaces with normal water use, the risk is low. However it requires active assessment - not an assumption. Where the risk is higher, a documented management plan with regular controls is required.

Water System Risk Review and Risk Assessment

The starting point is a Water System Risk Review to establish a full understanding of the water system on the premises. This should cover: any dead legs or areas where water is not flowing, the temperature of water at outlets, whether water is stored in tanks, any outlets that are used infrequently, and whether any high-risk systems are present such as showers, eye wash stations, cooling towers or water features.

Following the risk review, a Legionella risk assessment should be completed. This assesses the likelihood and severity of Legionella risk based on the findings of the review and identifies the controls needed. The risk assessment should be completed and reviewed by a competent person.

Legionella Management Plan

Where Legionella risk is identified, a Legionella Management Plan should be put in place. The plan should document all control measures, monitoring arrangements, testing requirements, the responsible person, and actions to be taken if a problem is found. It should also include a schematic or description of the water system.

Common control measures include regular flushing of infrequently used outlets - which may need to be done weekly - cleaning of shower heads, typically quarterly, maintaining hot water storage at 60 degrees Celsius, inspection and cleaning of any water tanks, and flushing the system after periods of inoccupancy. Where testing of water temperatures or sampling is required, this should be documented.

Legionella is one of those risks that is easy to overlook because the water system is largely invisible and nothing usually goes wrong. But if someone contracts Legionnaires' disease from your premises the consequences are serious - both for the individual and for the organisation. The risk review and risk assessment are not difficult to complete for most premises, and once the management plan is in place the ongoing controls become routine. The key is making sure it is done by someone who knows what they are looking at, not just ticking a box.

Practical Compliance Guidance

Managing Legionella risk requires a documented approach covering risk review, risk assessment and an ongoing management plan with regular checks. Firstly, you should establish if your work in a premises that has a legionella risk. If this is the case, a documented risk assessment can be carried out to highlight any controls that should be in place, where water sources are located and where the risk lies. Controls may include frequent tests carried out when running water, and the risk depends on the age of the building you occupy.

The alphaZ document suite includes specific Legionella forms to support this. Section 3.2 of IMS1 covers the management of premises and should reference the Legionella arrangements in place.

For complex water systems or higher-risk premises, it is worth engaging a specialist water hygiene contractor to carry out the initial risk review and assessment, and to advise on the management plan. For straightforward premises with simple water systems, a competent person within the organisation may be able to complete the review with reference to the HSE's Approved Code of Practice on Legionella (L8).

alphaZ document	How to use it
ISO 9001/14001/45001 Management System Toolkit	The complete toolkit for implementing an ISO-compliant integrated management system. Includes the IMS1 manual, all policies, procedures, registers and audit checklists.
GG-7-22 Legionella Safety Guidance	General guidance on Legionella, the associated risks and how to manage them. Includes specific guidance on completing the Legionella Risk Review.
F-HS36 Legionella Risk Review	Use to document the initial water system risk review - covering water system layout, temperatures, storage, infrequently used outlets and any high-risk systems present.
RA-HS62 Legionella Risk Assessment	Example Legionella risk assessment. Complete following the risk review to formally assess and record the level of risk and the controls in place.
F-HS37 Legionella Management Plan	Use to document the Legionella management arrangements - controls, monitoring schedule, responsible person, testing requirements and actions to take if a problem is identified.

Note - all the above files can be downloaded with an alphaZ subscription.

Frequently Asked Questions

Does every workplace need a Legionella risk assessment?

Yes. Under the Control of Substances Hazardous to Health Regulations 2002 (COSHH) and the HSE's Approved Code of Practice L8, anyone responsible for premises with a water system has a duty to assess the risk of Legionella. This applies to all workplaces - the assessment may conclude that the risk is low and no further action is needed, but the assessment itself must be done and documented. Simply assuming the risk is low without completing an assessment is not sufficient.

We only have a basic cold mains water supply with no tanks or showers. Do we still need to do anything?

A simple water system with a direct cold mains supply and no water storage, no showers and regular water use at all outlets typically presents a low Legionella risk. However a brief documented risk review confirming this is still good practice - it records that the assessment was considered and demonstrates the basis for concluding that risk is low. If circumstances change - a shower is installed, premises are unoccupied for a period, or a water tank is added - the assessment should be reviewed.

How often should Legionella checks be carried out?

The frequency depends on the risk level and the specific control measures in the management plan. Infrequently used outlets typically need to be flushed weekly. Shower heads typically need cleaning quarterly. Water temperatures at a sample of outlets should be checked periodically. Water tanks need periodic inspection and cleaning. The management plan should specify the frequency for each control measure based on the risk assessment findings, and records of all checks should be retained.

UK Legislation

The following UK legislation and guidance is directly relevant to the management of Legionella risk. Organisations outside the UK should identify the equivalent legislation and guidance applicable in their jurisdiction.

Further Resources