Legionella Detected in Your Water System?
A Step-by-Step Guide to Action | PTS
Receiving a water test result indicating the presence of Legionella bacteria can be a serious concern for any Duty Holder. However, a positive detection doesn’t need to cause panic. Instead, it signals the need for prompt, informed action to manage potential risks and ensure your water system is safe and compliant. Pipe Testing Services (PTS) provides expert guidance and comprehensive services across the UK to help you effectively respond when Legionella is detected.
Our experienced water hygiene consultants are here to help you understand your results, navigate your legal responsibilities under ACOP L8, and implement the necessary corrective measures to bring your system back under control. This guide outlines what a positive result means and the steps you should take.
Understanding Your Legionella Test Results:
What Do the Numbers Mean?
When you receive a Legionella testing certificate from a UKAS-accredited laboratory, the results are typically reported in Colony Forming Units per litre (CFU/L). Understanding these levels is key to determining the appropriate response, as guided by the HSE’s HSG274 Technical Guidance Part 2 (for hot and cold water systems):
- Legionella <100 CFU/L: Generally considered an acceptable level in many systems. Your current control measures are likely effective. You should continue with your routine monitoring and risk assessment schedule.
- Legionella ≥100 CFU/L but <1000 CFU/L: This indicates that Legionella bacteria are present and multiplying. Your control measures should be urgently reviewed. A resample is typically recommended to confirm the reading. If levels are consistently in this range, a system clean and disinfection may be necessary.
- Legionella ≥1000 CFU/L: Requires immediate action. Your system is not under control. The Legionella Risk Assessment must be reviewed, control measures immediately checked and rectified, and the system will likely require cleaning and disinfection. Further investigation to find the source of contamination is crucial.
It’s important to note that different types of water systems (e.g., cooling towers, covered by HSG274 Part 1) or specific environments (like healthcare premises, following HTM 04-01) may have different or stricter action thresholds. Any detection of Legionella pneumophila serogroup 1, the most virulent strain, should always be taken very seriously, regardless of the count.
Immediate Steps if Legionella is Detected at Actionable Levels
If your test results show Legionella at levels requiring action, a swift and structured response is essential. Firstly, do not ignore the result. While not every detection means an immediate outbreak, it does indicate that your control measures need urgent attention.
If your test results show Legionella at levels requiring action, a swift and structured response is essential. Firstly, do not ignore the result. While not every detection means an immediate outbreak, it does indicate that your control measures need urgent attention.
Consult your current Legionella Risk Assessment; it should outline procedures for when control limits are breached. It’s also highly advisable to seek expert advice from a competent water hygiene specialist, such as Pipe Testing Services. We can help interpret the results in the context of your specific system. For very high counts, or if the affected outlets are in high-risk areas (e.g., showers used by vulnerable individuals), you may need to consider temporarily restricting access until the situation is assessed and managed. Crucially, review your current control measures: are daily and weekly tasks like flushing and temperature checks being performed correctly and recorded?
How PTS Helps You Respond to a
Positive Legionella Detection
Pipe Testing Services provides a comprehensive, step-by-step approach to help you manage the situation effectively and compliantly:
- Expert Result Interpretation & Consultation: Our consultants will review your Legionella test certificate and discuss its implications with you, considering your specific water system design and the findings of your Legionella Risk Assessment.
- Urgent Review of Control Measures & Risk Assessment: We help you investigate why Legionella was detected. This often involves an immediate review of your current control scheme, temperature logs, flushing records, and the existing risk assessment to identify potential failings or new hazards.
- Targeted Re-sampling (if necessary): In some cases, particularly for borderline results, re-sampling specific outlets or areas might be advised to confirm the extent of the issue before proceeding with extensive remedial action. See our Legionella Testing Services.
- Implementing Effective Legionella Remedial Works: Our qualified engineers can undertake a wide range of necessary actions, including:
- Full water system cleaning and disinfection (often to BS 8558 standards using Chlorination Services).
- Cleaning, descaling, and disinfection of cold water storage tanks and hot water calorifiers.
- Thorough cleaning, descaling, and disinfection of shower heads, hoses, and affected outlets.
- Removal of dead legs or redundant pipework promoting stagnation.
- Servicing or installation of Thermostatic Mixing Valves (TMVs) to ensure safe hot water temperatures while allowing system disinfection.
- Post-Remediation Verification: After remedial works and disinfection, further water sampling is usually essential to verify that the actions have been effective in reducing Legionella counts to acceptable levels.
Why Choose PTS When Legionella is Detected?
Discovering Legionella in your water system requires a swift, competent, and reliable response. Pipe Testing Services offers the expertise and resources needed to manage the situation effectively. Our team understands the urgency and provides prompt guidance and support. Moreover, our qualified engineers have extensive experience in diagnosing system faults and implementing effective remedial solutions in line with ACOP L8 and HSG274.
We provide comprehensive solutions, from helping you interpret your initial test results and reviewing your risk assessment, through to carrying out necessary remedial works and post-remediation verification sampling. Our focus is not just on immediate fixes but on helping you implement robust control measures to prevent recurrence. With nationwide coverage, PTS is your trusted partner for managing positive Legionella detections and ensuring long-term water safety.
Understanding the Costs of Addressing a Positive Detection
The costs involved in responding to a Legionella detection will vary based on several factors. These include the size and complexity of your water system, the level of Legionella contamination found, and the specific remedial actions identified as necessary by the updated risk assessment. For instance, simple system flushing and a precautionary disinfection will cost less than extensive pipework modifications or tank replacement.
PTS always provides transparent, itemised quotations for any recommended works. It is important to remember that prompt and effective action following a positive detection is often more cost-effective in the long run than delaying, which can lead to higher contamination levels, more extensive remedial works, and increased risk to health and potential legal consequences.
Urgent Action Required?
Contact PTS for Legionella Detection Support
If you’ve received positive Legionella test results, don’t delay. Contact Pipe Testing Services for expert advice, effective solutions, and support in bringing your water system back to a safe and compliant state.
Our specialist water hygiene team is ready to assist you nationwide:
- Phone – 01922 451646
- Email – enquiries@pipetestingservices.co.uk
- Address – Unit 27 Birchbrook Industrial Estate, Shenstone, Lichfield, Staffs, WS14 0DJ
Let PTS help you navigate this challenge and ensure the ongoing safety of your water systems.
Legionella Detected - FAQs
As the Duty Holder, your immediate legal duty is to take reasonably practicable steps to control the risk. This involves reviewing your Legionella Risk Assessment, implementing corrective actions identified (which may include system disinfection and remedial works), and keeping records. You must protect people from exposure.
This depends on the levels detected, the specific outlets affected (e.g., showers vs. handwash basins), and the vulnerability of the people using the water. For high counts or high-risk outlets, PTS may advise temporary restrictions on use until the system is treated and re-tested. Always seek expert advice.
PTS understands the urgency. We aim to provide a prompt response for consultation and, if necessary, to schedule site visits and remedial actions as quickly as possible. Contact us immediately to discuss your situation.
Not always. Many remedial actions, like targeted flushing or outlet disinfection, can be done with minimal disruption. Larger scale disinfections or pipework modifications might require planned, temporary shutdowns of parts or all of the system, which we would schedule with you to minimise impact.
Effective remedial works and system disinfection will significantly reduce or eliminate Legionella. However, ongoing adherence to your reviewed Legionella Risk Assessment and written control scheme, including regular Legionella Monitoring (temperature checks, flushing etc.), is crucial to prevent re-colonisation.