Microbiological Testing - Legionella Testing

Legionella bacteria present a serious risk to health if allowed to proliferate in water systems, resulting in a potentially fatal form of pneumonia known as Legionnaires disease. Responsible duty holders are legally required to manage this risk under the Health and Safety at Work etc. Act 1974, the Control of Substances Hazardous to Health Regulations (COSHH), and the guidance contained in ACoP L8 and HSG274 Part 2.

At Envirochem, we provide UKAS-accredited (testing laboratory No. 1227) Legionella testing and analysis, helping you verify the effectiveness of control measures and maintain compliance following Legionella risk assessments. Our services combine accurate reporting and expert interpretation that ensures you can act quickly on results, safeguarding both your facilities and your clients’ reputations.

Where We Test

Legionella bacteria can colonise many types of water systems, including domestic hot and cold-water supplies, cooling towers, spa pools, and storage tanks. Envirochem analyses samples from a wide range of systems, including:

Hot and cold-water outlets and storage vessels
Showers, taps, and thermostatic mixing valves (TMVs)
Spa pools, hydrotherapy pools, and leisure facilities
Decorative fountains, evaporative condensers, and air-handling units
Ships, ferries, and other vessel water systems

Testing identifies and quantifies Legionella pneumophila and related species using culture-based methods aligned with recognised standards such as BS 7592 and ISO 11731:2017, ensuring results are accurate and traceable.

Our Process

Each Legionella testing programme begins with a discussion to understand your water system design, control scheme, and existing risk assessment findings. We can also provide guidance on sampling frequency and safe sample collection.

Samples are analysed within our UKAS-accredited laboratory (No. 1227) using validated culture techniques. Results are issued clearly, with colony-forming unit (cfu) counts and interpretation against action and alert levels recommended by HSG274 Part 2. Where elevated counts are identified, our team can advise on appropriate next steps, including system disinfection, review of control measures, or re-sampling after remedial action.

For domestic or small-scale systems, Envirochem also offers Legionella self-sampling testing and analysis kits through our online store, allowing you to safely collect samples and return them to our UKAS-accredited laboratory (No. 1227) for analysis.

When is Legionella Testing Required?

Legionella bacteria thrive in water temperatures between 20–45 °C, making consistent temperature control and regular monitoring essential. Legionella testing is a key part of demonstrating effective control and is often required:

Following a Legionella risk assessment that identifies potential exposure
As part of routine monitoring for healthcare, leisure, and accommodation providers
After significant system alterations, maintenance, or periods of stagnation
When temperature control alone may not reliably prevent bacterial growth
In high-risk settings, such as hospitals, care homes, and spa facilities

As per HSE guidance, open water systems such as cooling towers, evaporative condensers and spa pools should be tested at least quarterly, with frequency adjusted according to system type, risk assessment, and guidance under ACoP L8 and HSG274 Part 2.

Compliance and Risk Considerations

Failing to monitor and control Legionella effectively can have significant health, legal and reputational consequences. The bacteria thrive in water systems where temperatures, stagnation, or poor maintenance allow biofilms to form. Legionnaires' disease, a potentially fatal form of pneumonia, is contracted by inhaling small droplets of water suspended in the air that contain the bacteria. Because it is so dangerous, even a single case of this disease linked to a site can trigger public health investigations, enforcement notices, and lasting damage to client confidence.

From a compliance standpoint, duty holders must manage Legionella risk in line with the Health and Safety at Work etc. Act 1974, the Control of Substances Hazardous to Health Regulations (COSHH), and the guidance set out in ACoP L8 and HSG274 Part 2. Healthcare premises are additionally governed by HTM 04-01, which sets more stringent requirements for water safety and verification.

These frameworks establish the legal expectation that every organisation understands the condition of its water systems and can evidence ongoing control. Routine testing offers early detection of bacterial growth, verifying that maintenance measures are effective, and demonstrating compliance to regulators, insurers and clients.

Why Choose Envirochem?

Envirochem has over 30 years of experience supporting organisations with Legionella testing. All analysis is carried out in our in-house UKAS-accredited laboratory (No. 1227), giving clients complete traceability and confidence from sample receipt to reporting.

Our team brings together microbiologists, chemists and field consultants who understand the operational realities of water management. We help you interpret your results, assess control effectiveness, and plan next steps in line with your duty-of-care obligations under ACoP L8, HSG274 Part 2 and HTM 04-01.

Because we work across chemical, microbiological and occupational hygiene disciplines, we provide joined-up advice that considers the full picture of compliance, maintenance and risk. Whether you are validating the outcome of a recent risk assessment, implementing routine monitoring, or responding to a positive result, Envirochem offers a responsive, technically grounded service that supports safe and compliant water systems.

Speak to Our Team

If you require Legionella testing or need to verify compliance following a risk assessment, get in touch with our team. We’ll work with you to interpret results and recommend next steps to keep your systems compliant and your users safe.