Legionella Testing

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Legionella Testing Services

Keeping your water systems safe is a core responsibility for any facilities manager. Legionella testing is an important part of this work and helps you confirm that your water systems remain under control. A structured approach to testing provides reassurance that your building meets Health and Safety Executive guidance and supports your wider water hygiene plan.

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Legionella testing involves taking samples from selected outlets, tanks or water heaters and analysing them in a laboratory to check for the presence of Legionella bacteria. UKAS accredited laboratories use recognised methods to identify whether live bacteria are present so that building operators can take informed action if required. Whether you manage a commercial property, a healthcare facility or an industrial site, regular testing can form part of a safe and compliant water management programme.

Your Trusted Partner for Legionella Testing

If you’re here, there’s a good chance you need Legionella testing - maybe as part of your ongoing compliance programme, or because a recent risk assessment identified a potential issue.

You’ve come to the right place. At Titan Water, we provide professional Legionella sampling and microbiological testing services for all types of water systems. From hot and cold outlets to tanks, calorifiers, and showers - we collect, transport, and analyse samples to the highest UKAS-accredited standards.

We take a practical, transparent approach. Our sampling engineers are fully trained to follow HSE and ACOP L8 guidance, ensuring every sample is taken correctly and securely. You’ll receive clear laboratory results and an easy-to-understand report explaining what they mean - not just a spreadsheet of numbers. Whether you need routine testing or reactive sampling after an incident, Titan Water can give you the clarity and confidence to take the right action.

Nationwide Service
Reliable Expertise Wherever You Are

Our experienced management team operate from the Titan head office near Liverpool, but while our roots are firmly in the North West, our reach goes far beyond it. Our engineers carry out Legionella sampling projects across the UK, supported by a trusted network of regional specialists and accredited laboratory partners. Whether it’s a hotel in Edinburgh, a healthcare facility in Leeds, or a manufacturing site in Bristol, we’ve been there – and we know the importance of reliable, accurate water sampling.

If you need scheduled Legionella sampling, or want confirmation that your existing results are still within safe limits, the team at Titan are always happy to help with practical, straightforward advice.

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What Is Legionella Testing

Legionella testing is the process of assessing water samples for Legionella bacteria. Testing helps identify whether control measures are working and supports compliance with ACOP L8 and HSG274 guidance. It can also offer early warning of issues that may not be visible from routine temperature checks or flushing records.

If you are reviewing your wider water safety responsibilities, you may find it helpful to refer to our dedicated page on Legionella Risk Assessment Services.

Why Test for Legionella

Legionella bacteria occur naturally in water but can multiply in man made systems where water is warm, stagnant or poorly circulated. When bacteria become airborne in fine droplets, people can inhale them and develop Legionnaires disease. Testing helps you spot developing problems and maintain confidence in your control measures.

You may consider Legionella testing if:

Your building serves vulnerable users
There are complex or ageing water systems
There has been a significant change in how the system is used
Temperature or flushing checks fall outside acceptable ranges
Refurbishment or maintenance work may have affected water quality

Testing is often part of an ongoing programme of monitoring. For more on the wider control measures involved, see our dedicated page Water Hygiene Monitoring Services.

When Should Legionella Testing Be Carried Out?

Sampling frequency depends on the type of system and level of risk. HSE guidance recommends sampling:

Routinely, in high-risk environments such as hospitals, care homes, and leisure facilities.
Periodically, as part of an ongoing monitoring programme for cooling towers or complex water systems.
Reactively, following positive Legionella results, major system changes, or when control measures may have failed.
After system disinfection, to confirm that remedial works have been successful.

For many commercial premises, Legionella sampling is undertaken every 6 to 12 months, but higher-risk sites may require more frequent testing. Titan Water can help you build a sampling schedule that fits your specific system and compliance requirements. You can read more about this in our blog BS 7592:2022 Legionella Sampling Guidance | Titan Water

How Legionella Testing Works

Legionella testing should be carried out using established sampling techniques and laboratory analysis. The two most common laboratory methods are culture testing and PCR testing.

Culture Testing

Culture testing is the recognised standard for compliance. Water samples are taken and processed in a UKAS accredited laboratory where any Legionella bacteria present are allowed to grow on selective media. Results are measured in colony forming units per litre and provide clear, quantitative evidence of whether live organisms are present. Although results take longer to produce, they give reliable information that auditors and regulators expect.

PCR Testing

PCR testing is a rapid method that detects the DNA of Legionella bacteria. It provides faster results than culture testing and can be useful when time is a critical factor. Because PCR may detect both live and dead bacteria, it is usually used alongside culture testing rather than as a direct substitute.

Other Screening Methods

There are also on site tests that help provide an early indication of potential issues. These do not replace laboratory analysis but can support investigation work and pinpoint areas that require further attention.

Where Samples Are Taken

A good sampling strategy is essential for meaningful results. Sampling points should reflect the areas of your system where risks are most likely to occur.

Common sampling locations include:

Hot and cold water outlets, particularly those furthest from the source
Showers and thermostatic mixing valves
Cold water storage tanks
Calorifiers and water heaters
Little used outlets or areas with low flow

During sampling, details such as temperature, location and time of collection are recorded to support a clear audit trail. You can do a deeper dive on this in our blog How to Test for Legionella Bacteria in Water | Titan Water

What Happens After Legionella Samples Are Taken?

Once samples are collected, they’re carefully labelled, temperature-controlled, and transported to a UKAS-accredited laboratory for analysis. Results typically take between 7 to 10 days, depending on the laboratory’s processing times.

You’ll receive a detailed report that includes:

Laboratory findings showing any Legionella species detected.
Interpretation of results based on HSE thresholds.
Recommended next steps, including any disinfection, flushing, or retesting required.

Understanding Your Legionella Test Results

Once analysis is complete, results will help determine whether your system is performing as expected.

No Detection

If Legionella is not detected, your control measures are generally working well. Continue the routines already in place, including temperature checks, flushing and regular system maintenance.

Low Levels Detected

Low positive results do not always indicate a major failure but should prompt a review of your control measures. Check recent temperatures, flow conditions and usage patterns. Targeted cleaning or adjustments may resolve the issue.

High Levels Detected

Elevated results require immediate action. This may include temporarily restricting access to certain outlets, carrying out system disinfection or commissioning a targeted investigation. Clear communication with duty holders and accurate record keeping are essential at this stage.

If results indicate elevated levels of Legionella, your Titan Water Account Manager will work with you to investigate the root cause, implement corrective actions, and confirm the system’s return to safe operation through follow-up testing.

In short, we don’t just take samples - we help you understand them and act on them.

If you are managing an investigation following a positive result or a system failure, you may find our Legionella Investigation page useful.

How Legionella Testing Supports Long Term Control

Legionella testing is most effective when it forms part of a structured water safety plan. A combination of testing, monitoring, maintenance and clear records creates a predictable and well managed system. Facilities managers who integrate testing into their ongoing processes find it easier to demonstrate compliance and respond quickly to any future issues.

Frequently Asked Questions

How long does Legionella testing take from sample collection to results

Most laboratory culture tests take around ten to fourteen days to process because the bacteria need time to grow on selective media. Faster PCR options exist and can provide an early indication within hours, although they are usually used as a supplement to culture testing rather than a replacement.

Do I need to test for Legionella if my temperature records are always within range

Temperature control is an important part of managing Legionella risk, but it does not guarantee that bacteria are not present. Testing offers an additional level of assurance and can confirm whether your control measures are performing as expected. Many organisations choose to test periodically even when routine checks are satisfactory.

Can Legionella testing be carried out while the building is in full use

Yes. Most sampling can be completed with minimal disruption to building users. You may need to provide short access to plant rooms or specific outlets, but systems usually remain operational during testing. Any recommendations following the results will be planned around your building’s needs.

Is Legionella testing required by law

There is no blanket legal requirement to test routinely, although testing may be necessary in certain circumstances based on your risk assessment. The Health and Safety Executive expects employers and duty holders to follow ACOP L8 and HSG274 guidance, which outline when testing is appropriate and what actions should follow.

How often should a commercial building consider Legionella testing

Frequency depends on the complexity and risk profile of your water systems. Sites with vulnerable occupants or more intricate pipework may require more regular testing. Others may test only when triggered by a change in use, failed control measures or refurbishment works. Your Legionella risk assessment should guide the appropriate schedule.

What happens if Legionella is detected during testing

If the results show the presence of Legionella bacteria, the next steps depend on the level detected and the nature of your system. This may involve reviewing control measures, increasing flushing, cleaning storage tanks or commissioning a system wide investigation. Clear communication with your responsible person or duty holder is important.

Can I take Legionella samples myself or does it require a professional

Sampling needs to follow specific procedures to ensure results are reliable and compliant. Using professional, trained personnel reduces the chance of contamination, ensures correct bottle handling and maintains chain of custody for the laboratory. Many duty holders prefer professional sampling for audit and insurance purposes.

Are there signs that suggest my system might need Legionella testing

You may consider testing if water temperatures are inconsistent, outlets are seldom used, tanks show signs of sediment buildup, or there have been significant changes to how the system operates. Unexpected odours, discoloured water or complaints from users can also be reasons to test.

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