Legionella Risk Assessment: Ensuring The Safety of Your Water System

What is a Legionella Risk Assessment (LRA), and Why is it Important?

An LRA is a process used to identify and assess the risks posed by legionella bacteria in water systems. LRAs are essential because they can help to prevent outbreaks of Legionnaires’ disease. Most Legionnaires’ disease outbreaks occur in places where contaminated water is available, such as hotels, hospitals, and cruise ships. In addition, LRAs can also help to ensure that water systems are properly maintained, thereby reducing Legionella risks.

What is Involved in an LRA?

LRAs involve two processes: physical inspection and risk assessment.

The physical inspection involves the following process:

• Assessment and documentation of the site, including water tanks and pipework designs with photographic proof
• Water supply and temperature testing at critical locations throughout the facility
• Conducting water flow and stagnation tests
• Inspection for hazards caused by aerosols
• Testing water samples from different parts of the water system

Risk assessment involves the following process:

• Review of previous assessments and any available water testing data
• Identification of potential sources of Legionella contamination
• Evaluation of the risks posed by these sources
• Determination of the need for additional control measures

A report is then prepared that documents the assessment findings and outlines any recommended control measures.

Is it a Legal Requirement to Have an LRA?

Not all countries require Legionella risk assessment forms or testing. However, it is strongly encouraged by health professionals from different countries, as it can help stop the spread of Legionnaires’ disease. In the US, although there is no federal law requiring property managers and landlords to conduct risk assessments or testing of any sort for Legionella, many authorities have argued that it should be to help promote safer drinking water and protect public health. Officials in some states have taken to conducting their own efforts to help manage Legionella through state-specific laws, particularly for cooling towers, water systems, healthcare facilities, and other related buildings.

However, there are some countries that require legionella testing and risk assessments. These include the following:

• The Netherlands;
• Germany, but only for large facilities that regularly heat drinking water, have an internal water storage capacity of more than 400 liters, and have a pipeline volume of at least three liters;
• UK;
• France;
• Australia; and
• Canada

Who is Responsible for Carrying Out an LRA?

Anyone can perform the LRA. But, the person who understands the facility’s water management systems should perform the LRA. The accountable individual should also have enough power to implement the audit findings. This individual must guarantee conformance and, in the end, prevent Legionella bacteria from developing.

According to ACoP L8 regulations, a guidance document released by the UK’s Health and Safety Executive, the person conducting the assessment and implementing any control measures must have the “necessary expertise, experience, and knowledge.” And they are “properly trained to safely and effectively complete their tasks.”

Landlords with few tenants can perform the LRA themselves-provided they have the proper training. If the property is complex or has many tenants, it would be best to hire a professional to conduct the assessment. This way, they can ensure optimal safety for the people in the building.

When Should You Conduct a Legionella Risk Assessment?

The industry standard was LRA should be conducted at least every two years. However, per advice by the Approved Code of Practice L8 (ACoP L8), assessment must be conducted “more frequently if there is a valid reason to do so.” to keep the assessment updated.

LRA updates may be necessary for the following reasons:

• The presence of vulnerable people with health risks in the building;
• Occupancy of the vacant units;
• Changes in water use or system design;
• A reported case of Legionnaires’ disease;
• Major repair or maintenance work on the water system; and
• Failure of control measures.

In general, any time there is a change that could potentially affect the growth or spread of Legionella bacteria, an LRA should be conducted.

How to Conduct a Legionella Risk Assessment?

Landlords, employers, and property managers can use the following steps as a guide in performing a Legionella risk assessment and in managing Legionella risks:

Step 1: Determine Overall Risk

The first step in carrying out a Legionella risk assessment is to determine if there is a risk. Check if any of the top 3 Legionella-related risk factors are present. Also check for other Legionella-related risk factors such as:

• Water is being stored or re-circulated as part of the water system
• Sources of nutrients for Legionella, such as rust, sludge, scale, organic matter, and biofilms, are present
• Water droplets are being produced or can be produced
• Water droplets can be dispersed over a wide area (e.g., showers and aerosols from cooling towers)
• Any employee, resident, or visitor is more susceptible to Legionella infection due to age or illness, such as a weakened immune system
• If the person who is more susceptible to Legionella infection could be exposed to any contaminated water droplets

If there is currently no risk, determine if there is a possibility that a risk will occur. If there is no reasonably foreseeable risk, according to the HSE, the Legionella risk assessment is complete.

If there is a risk, determine the risk level. If the risk level is low and risk is being properly managed to comply with the law, according to the HSE, the Legionella risk assessment is complete. Indications that the Legionella risk level is low (based on examples given by the HSE):

• Use of hot and cold water systems
• Use of small, domestic-type systems
• Regular water usage and turnover
• No stored water tanks

Step 2: Test for Legionella if Needed

To test for Legionella, the HSE recommends doing the following:

• Use the BS 7592 standard for water sampling
• Neutralize biocide if used and where possible
• Submit water sample to a UKAS-accredited laboratory that takes part in a water microbiology proficiency testing scheme
• Ensure that the UKAS-accredited laboratory applies the minimum theoretical mathematical detection limit of <= 100 legionella bacteria per liter of sample for culture-based methods

Aside from cases where control measures do not seem to be effective, Legionella testing is typically only carried out for cooling tower systems, though it is also recommended for other open systems such as evaporative condensers and spa pools. Although in recent years, it has also been encouraged for establishments in which water is constantly heated and cooled repeatedly and then distributed for human use or consumption. Additionally, the HSE states that these systems should be tested for Legionella at least quarterly. However, take note that UK law does not require a Legionella test certificate, nor does the HSE recognize it.

Step 3: Fulfill Other Duties

Under the UK Notification of Cooling Towers and Evaporative Condensers Regulations 1992 (NCTEC), the local authority must be notified in writing if there is a cooling tower or evaporative condenser on site, and details about where it is located should be included. The local authority must also be notified when such devices are no longer in use.

Under the UK Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR), cases of Legionellosis (Legionnaires’ disease) in employees who have worked on cooling towers or on hot and cold water systems that are likely to be contaminated with Legionella must be reported.

For properties that are left vacant, water should not be allowed to stagnate within the water system and outlets on hot and cold water systems should be used at least once a week. 

Using SafetyCulture in Conducting Legionella Risk Assessment