Your Trusted Partner for Legionella Testing
✔ UKAS accredited laboratory analysis
✔ Fully compliant with HSG274 and ACOP L8
✔ Trusted by commercial and public sector clients
✔ Serving the North West and beyond
Keeping your water system safe is a legal responsibility, not just best practice. Regular legionella testing helps confirm that your control measures are working, supports compliance with HSG274 and ACOP L8, and provides the documented evidence you need to demonstrate due diligence.
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At Titan Water, we carry out professional water sampling from agreed outlets, tanks, and plant throughout your building. Samples are sent to a UKAS accredited laboratory for microbiological analysis. You receive clear, written results with plain-English interpretation and practical advice on next steps.
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Whether you manage a commercial property, a healthcare facility, a care home, or an industrial site, regular legionella testing can form part of a safe and compliant water hygiene management programme.
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What Does Legionella Testing Involve?
Legionella testing involves collecting water samples from key points within your building's water system. Common sampling locations include hot and cold outlets, cold water storage tanks, calorifiers, showers, and thermostatic mixing valves.
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Samples are collected by our trained engineers following recognised procedures in line with BS 7592, which governs sampling for legionella bacteria in water systems. They are then sent to a UKAS accredited laboratory for culture analysis or PCR testing.
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Results are typically returned within 7 to 10 working days and include a written report detailing findings, the level of any bacteria detected, and recommended next steps. Where results indicate a problem, we can advise on and carry out the appropriate legionella remedial works.​​​​​​
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Nationwide Service
Reliable Expertise Wherever You Are
Our management team works from Titan Water's head office near Liverpool. From there, our engineers carry out legionella water sampling for clients across the North West and wider UK.
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We carry out water sampling for hotels, healthcare sites, care homes, commercial buildings, leisure facilities, and industrial systems. If you need routine sampling, follow-up checks after a positive result, or support after a system change, we can help you plan the right next step.
Your Questions Answered
What Is Legionella Sampling
Legionella sampling checks water for the presence of Legionella bacteria. Samples are taken from selected points in your water system and sent to an accredited laboratory for analysis.
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This helps show whether your control measures are working. It can also highlight hidden problems that may not be obvious from temperature checks, flushing records, or visual inspections.
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Legionnaires' disease can be serious and potentially fatal, particularly for vulnerable people. That is why accurate sampling and clear follow-up action matter. You can read more about the risks in our guide to Legionnaires' disease.
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Why Test for Legionella
Legionella bacteria can occur naturally in water. They can multiply in man-made systems when water is warm, stagnant, or poorly circulated.
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If contaminated water becomes airborne in fine droplets, people may breathe it in. This can lead to Legionnaires' disease. You can read more about the conditions that allow bacteria to spread in our article on what causes Legionnaires' disease in buildings.
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Sampling helps identify developing problems before they become harder to control. You may need to sample if:
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Your building serves vulnerable users
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There are complex or ageing water systems
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There has been a significant change in how the system is used
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Temperature or flushing checks fall outside acceptable ranges
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Refurbishment or maintenance work may have affected water quality
Testing is often part of an ongoing monitoring programme. For more on the wider control measures involved, see our water hygiene monitoring services page.
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When Should Legionella Sampling Be Carried Out?
The right sampling frequency depends on your system, risk level, and control measures. Your legionella risk assessment should guide the schedule.
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Sampling may be needed more frequently if:
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You manage a higher risk site such as a hospital, care home, or leisure facility
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Your system includes spa pools, cooling towers, or complex water systems
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There have been poor temperature results or failed control measures
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Work has recently been carried out, including cleaning, disinfection, or remedial works
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A previous test returned a positive result
For many commercial buildings, sampling may be carried out every 6 to 12 months. Higher risk sites may need checks more often.
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Who Needs Legionella Testing?
Any organisation that operates a water system has a duty of care under the Health and Safety at Work Act 1974 and the Control of Substances Hazardous to Health Regulations.
Legionella testing is particularly relevant for:
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Hotels, care homes, and hospitals where vulnerable people are present
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Commercial office buildings and multi-occupancy premises
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Facilities managers responsible for multiple sites
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Landlords of residential properties with complex water systems
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Schools, leisure centres, and public sector buildings
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Industrial sites with cooling towers or evaporative condensers
If you are unsure whether your building needs legionella testing, a legionella risk assessment is the best starting point. It will identify your risk level and set out a monitoring schedule appropriate to your system.​​​​
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How The Sampling Process Works
Water samples should be taken using the correct method. ​This helps avoid contamination and makes the results more reliable.
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The two most common laboratory methods are culture analysis and PCR analysis.
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Culture Testing
Culture analysis is the recognised method for compliance.
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Samples are processed in a UKAS accredited laboratory. Any live Legionella bacteria present are allowed to grow on selective media.
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Results are measured in colony forming units per litre.
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This method takes longer, but it gives the type of evidence auditors and regulators usually expect.
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PCR Testing
PCR analysis is a faster method.
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It detects Legionella DNA and can give an early indication when time is critical.
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However, PCR may detect both live and dead bacteria. For that reason, it is often used alongside culture analysis rather than as a direct replacement.
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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.​
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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.
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Common sampling locations include:
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Hot and cold water outlets, particularly those furthest from the source
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Showers and thermostatic mixing valves
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Cold water storage tanks
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Calorifiers and water heaters
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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
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What Happens After Legionella Samples Are Taken?
Once samples are collected, they are labelled and handled carefully.
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They are then transported to a UKAS accredited laboratory for analysis.
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Culture results usually take around 7 to 10 days, depending on the laboratory.
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Your report should show:
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Whether Legionella bacteria were detected
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The level found, where applicable
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What the result means
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Recommended next steps
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 controls are likely to be working.
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You should continue routine checks, flushing and maintenance.
Low Levels Detected
A low result does not always mean a major failure. It should still trigger a review of temperatures, water movement and usage patterns.
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Targeted cleaning, flushing or adjustments may be enough to bring the system back under control.
High Levels Detected
High results need prompt action. ​This may include restricting access to outlets, disinfecting parts of the system or arranging a targeted investigation.
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The key is to stay calm, act quickly and keep clear records.
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If bacteria are found, the next step is usually to review the parts of the system most likely to be contributing.
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Extra flushing
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Temperature checks
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Tank cleaning
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Shower head cleaning
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Further sampling
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Remedial works
In some cases, corrective work is needed to remove the underlying cause.
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Helpful reading:
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https://www.titanwater.co.uk/post/understanding-legionella-remedial-works
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https://www.titanwater.co.uk/post/how-to-prioritise-legionella-remedial-works
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https://www.titanwater.co.uk/post/why-are-legionella-remedial-works-so-important
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If you are managing an investigation following a positive result or a system failure, you may find our Legionella Investigation page useful.
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How Legionella Sampling Supports Long Term Control
Sampling works best when it forms part of a wider water safety plan. It should sit alongside temperature monitoring, flushing, maintenance, and clear record keeping.
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This gives duty holders better evidence that the system is being managed properly, and makes it easier to respond quickly if results change in the future. For more on building a complete compliance programme, visit our water hygiene monitoring services page.
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Speak to an Expert
If you need support with your legionella testing programme, want to discuss the findings from recent sample results, or are unsure what level of sampling is right for your system, speak directly with our team. We can help you understand your obligations and build a testing schedule that fits your building and your budget.
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What Our Clients Say
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Legionella Testing Legal Requirements
There is no single legal duty that requires legionella testing at fixed intervals. However, duty holders have a legal obligation under the Health and Safety at Work Act 1974, the Management of Health and Safety at Work Regulations 1999, and the Control of Substances Hazardous to Health Regulations to assess and control the risk from legionella.
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ACOP L8 and HSG274 provide the practical framework for doing so. Both documents make clear that water sampling should be part of a routine monitoring programme where the risk assessment identifies it as a suitable control measure.
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In practice, this means many organisations are expected to carry out regular testing as part of demonstrating compliance, even if no specific interval is prescribed by law. Where a positive result is found and action is not taken, the legal exposure for duty holders increases significantly.
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Frequently Asked Questions
How long does legionella testing take from sample collection to results?
Most culture results take around 7 to 10 days. This is because the bacteria need time to grow in the laboratory. Faster PCR options may be available when urgent early information is needed.
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What is the difference between legionella testing and a legionella risk assessment?
A legionella risk assessment identifies the potential risks within your water system — its design, condition, and the likelihood of legionella growth. Legionella testing involves physically sampling the water to check whether bacteria are actually present. Both are important parts of a complete water hygiene programme, and one does not replace the other.
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What happens if my water tests positive for legionella?
A positive result does not necessarily mean there is an immediate danger, but it does require prompt action. We will advise you on the appropriate remedial steps, which may include system disinfection, temperature adjustments, or targeted cleaning. We can carry out those remedial works and retest to confirm the system is back under control.
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Do I need to test for legionella if my temperature records are always within range?
Possibly. Good temperatures are important, but they do not always prove bacteria are absent. Sampling gives extra assurance, particularly in higher risk systems or where vulnerable people may be affected.
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Can legionella testing be carried out while the building is in full use?
Yes. Most sampling causes very little disruption. Engineers usually need short access to plant rooms, outlets, or tanks.
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Are your laboratory results UKAS accredited?
Yes. All water samples collected by Titan Water are sent to a UKAS accredited laboratory for analysis, ensuring your results meet the standards required for compliance purposes.
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Do you provide a written report?
Yes. Every legionella test includes a written report detailing the sampling locations, results, and any recommended actions. Reports are provided in digital format and can be stored as part of your water hygiene compliance records.
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How often should a commercial building consider legionella testing?
It depends on the risk profile of the system. Some buildings sample every 6 to 12 months. Higher risk sites may need more frequent checks. Your legionella risk assessment should set the schedule.
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