Why a Legionella Risk Assessment Is Non-Negotiable for Your Property

Whether you manage a commercial building, a rental property, or a large industrial facility, one legal and moral duty sits at the top of your water safety obligations and understanding and controlling the risk of Legionella bacteria. Yet despite the well-documented dangers, Legionella risk assessments remain one of the most overlooked areas of property compliance in the UK.

What Is a Legionella Risk Assessment?

A Legionella risk assessment is a systematic evaluation of a property's water systems to identify conditions that could support the growth and spread of Legionella bacteria. It is the foundational document underpinning your entire Legionella control programme.

A thorough assessment will typically cover:

• A full inventory of water systems - including hot and cold water storage tanks, calorifiers, pipework, outlets, and any ancillary equipment such as cooling towers or humidifiers

• Identification of risk factors - such as water temperatures outside safe ranges, dead legs in pipework, infrequently used outlets, and scale or biofilm build-up

• Assessment of those at risk - with particular attention to vulnerable individuals such as the elderly, immunocompromised people, or anyone with respiratory conditions

• Recommended control measures - including temperature monitoring regimes, flushing programmes, descaling, and disinfection where necessary

• A written scheme of control - a live document detailing ongoing responsibilities, monitoring frequencies, and corrective actions

  
  

The result is a clear picture of the risk level in your building and a practical roadmap for managing that risk going forward.

Who Is Required to Have One?

Under the Health and Safety at Work Act 1974, the Control of Substances Hazardous to Health (COSHH) Regulations 2002, and the Approved Code of Practice L8 (ACoP L8) published by the Health and Safety Executive (HSE), there is a clear legal duty on anyone responsible for a premises to assess and control the risk from Legionella.

This includes:

• Landlords  both residential and commercial who have a duty of care to tenants

• Hotel and hospitality operators

• Healthcare facilities

• Local authorities and housing associations

• Office building managers and facilities teams

• Leisure facilities, including gyms, spas, and swimming pools

• Industrial and manufacturing sites with cooling water systems

How Often Should a Risk Assessment Be Carried Out?

A Legionella risk assessment is not a one-time exercise. The HSE's ACoP L8 guidance states that assessments should be reviewed regularly and whenever there is reason to believe the original or current assessment may no longer be valid. Common triggers for a review include:

• Changes to the water system or building layout

• A change of use of the premises

• New information about risks or control measures

• A suspected or confirmed case of Legionnaires' disease linked to the building

• Changes in the population of occupants (for example, a care home taking in more vulnerable residents)

  
  

As a general rule of thumb, a full review is recommended at least every two years, though many responsible dutyholders choose to carry out annual reviews as best practice.

What Happens During an Assessment?

A qualified Legionella risk assessor will visit your site and carry out a thorough inspection of all water systems. This will typically involve:

1. Site survey and system mapping — documenting pipework runs, tank locations, outlet points, and system configuration

2. Temperature checks — measuring hot and cold water temperatures at storage and outlets to check against safe thresholds (cold below 20°C, hot above 50°C at outlets)

3. Visual inspection — looking for signs of scale, corrosion, stagnation, or biofilm

4. Review of existing records — checking whether previous monitoring, flushing, or treatment has been carried out correctly

5. Identification of risk areas — highlighting any dead legs, infrequently used outlets, or system deficiencies

6. Remedial recommendations — advising on any immediate corrective actions needed

Following the visit, you will receive a comprehensive written risk assessment report, along with a recommended action plan and, where appropriate, a written scheme of control.

Common Risks Found in Buildings

Some of the most frequently identified risk factors during assessments include:

Stored hot water below 60°C. Water that is stored at lower temperatures creates ideal conditions for Legionella growth. All calorifiers and hot water cylinders should store water at 60°C or above.

Cold water above 20°C. Cold water pipework running close to heat sources, or stored in warm areas such as loft spaces, can allow temperatures to rise into the danger zone.

Dead legs and infrequently used outlets. Sections of pipework with no flow, or taps and showers that are rarely used, allow water to stagnate and bacteria to multiply. Regular flushing programmes are essential.

Poorly maintained or unmaintained tanks. Cold water storage tanks that lack secure lids, are contaminated with debris, or haven't been inspected in years are a significant risk.

Lack of documentation. Even where control measures are in place, a lack of written records means there is no way to demonstrate compliance,  a legal risk in itself.

Yorkshire and the North: Local Expertise Matters

If your property is based in Yorkshire or the wider North of England, working with a locally based specialist brings real advantages. A team with knowledge of local water quality, the specific challenges of older building stock common across Yorkshire, and familiarity with local authority requirements can provide a faster, more responsive service than a national provider.

For professional Legionella risk assessments in Yorkshire, Absolute Water provides expert assessments carried out by experienced, qualified assessors, helping businesses and landlords across the region meet their legal obligations with confidence.

What to Look for in a Legionella Risk Assessor

Not all risk assessors are equal. When choosing a provider, look for:

• Relevant qualifications — assessors should hold recognised training such as City & Guilds, BOHS, or equivalent water hygiene qualifications

• Experience with your property type — residential, commercial, and industrial systems each have their own characteristics

• Clear, actionable reports — a good assessment report doesn't just identify risks; it tells you clearly what needs to be done and in what priority order

• Ongoing support — the best providers offer a relationship beyond the initial assessment, supporting you with monitoring, remediation, and re-assessment as needed

• Insurance and accreditation — ensure your provider carries appropriate professional indemnity insurance

  
  

Taking Action: Your Next Steps

If you haven't had a Legionella risk assessment carried out or if your last one is more than two years old now is the time to act. The legal duty is clear, the risks are real, and the consequences of non-compliance can be severe.

Here's a simple checklist to get started:

1. Identify your water systems — hot and cold storage, calorifiers, cooling systems, outlets

2. Check your records — when was your last assessment? Is it still current?

3. Commission a new assessment if needed from a qualified specialist

4. Implement recommended control measures — and document everything

5. Set up an ongoing monitoring programme — temperature checks, flushing logs, tank inspections

6. Review regularly — and update your assessment whenever circumstances change

Legionella control is not just a box-ticking exercise. It is a genuine duty of care — to your tenants, your staff, your visitors, and anyone else who uses water in your building. A proper risk assessment is the starting point for everything: without it, you cannot know what controls are needed, whether they are working, or whether you are meeting your legal obligations.

The good news is that with the right expertise on your side, compliance is straightforward. A well-conducted assessment, a clear written scheme of control, and a consistent monitoring programme will keep your building safe and your mind at rest.

If you're in Yorkshire and need expert guidance, get in touch with a specialist who understands both the technical requirements and the local landscape. Your duty of care starts with knowledge and knowledge starts with a risk assessment.