Your Trusted Partner for Legionella Investigations
If you’re here, there’s a good chance you’ve received a positive Legionella result - or you’re dealing with persistent failures that won’t go away. It’s a stressful moment for any duty holder, and knowing what to do next is essential.
You’re in the right place. At Titan Water, we specialise in Legionella investigations that identify the root cause of contamination and provide clear, practical steps to restore safety and compliance. Our team carry out detailed engineering surveys, assess control measures, review monitoring records, and examine system design to understand exactly why the problem has occurred.
We take a calm, methodical approach. No assumptions - just clear evidence, expert engineering insight, and a plan that gets your system back under control. Whether it’s a single positive sample or ongoing failures across a complex site, our investigations provide the clarity you need and the guidance required to protect people and meet HSE expectations.
Nationwide Service
Reliable Expertise Wherever You Are
Our experienced management team operate from our head office near Liverpool, but our investigative work takes us across the whole of the UK. From healthcare facilities and commercial buildings to industrial sites and educational campuses, our engineers carry out Legionella investigations wherever they’re needed.
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Whether you’ve had an isolated positive result or recurring system-wide contamination, we’ve dealt with cases just like yours - and we understand the urgency, technical complexity, and compliance pressures involved.
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If you need immediate support or expert guidance following a positive result, the team at Titan are always ready to help.
What Are Legionella Investigations and When Are They Needed?
A Legionella investigation is a detailed examination of your water system designed to identify the root cause of a positive Legionella result. When bacteria are detected - even at low levels - HSE expects duty holders to act quickly and carry out a competent investigation.
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Investigations are required when:
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Routine sampling identifies Legionella - read more about Legionella sampling in our recent blog - Legionella Sampling Guidance
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Multiple positive results occur over time
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A risk assessment highlights significant non-conformities
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Temperature or control failures are repeatedly recorded
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A system has been unused, altered, or poorly managed
An investigation establishes why the contamination occurred and what corrective actions are needed to restore safe operation.
What Is Included in a Legionella Investigation?
A professional investigation typically includes:
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Engineering survey – Inspection of tanks, calorifiers, plant, pipework, and system layout.
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Temperature checks and operational testing – Verifying key control measures.
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Review of monitoring records – Assessing whether routine checks have been effective.
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Sampling strategy review – Identifying whether sampling frequency or locations need adjusting.
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Risk assessment verification – Checking whether the existing document is accurate and up to date - read our blog "What is a Legionella Risk Assessment?" to learn more about these important documents.
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Root cause analysis – Identifying the most likely reasons for Legionella growth.
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Corrective action plan – Providing clear, practical recommendations with priority ratings.
You’ll receive a detailed investigation report documenting findings, evidence, and next steps - written clearly so both technical and non-technical stakeholders can understand it.
What Happens After a Legionella Investigation?
Following the investigation, Titan Water will provide a clear set of recommended actions tailored to your site. These may include:
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System flushing or shock disinfection
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Tank or calorifier cleaning - Visit our Water Tank Cleaning page for more insight on the process.
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Pipework modifications
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Improved flushing regimes
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Updating the Legionella risk assessment
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Adjusting sampling frequency
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Remedial works or system upgrades
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Training for staff responsible for routine monitoring
We can also carry out follow-up sampling to verify that corrective measures have been successful and the system has returned to safe control.
Frequently Asked Questions
What should I do immediately after receiving a positive Legionella result?
You should review recent temperature records, flush affected outlets, and notify the responsible duty holder. Avoid making major changes until an investigation is carried out, as this may disrupt the evidence needed to identify the cause.
Who is responsible for arranging a Legionella investigation?
The duty holder or responsible person named in your Legionella management system must ensure investigations happen promptly. This may be a building owner, facilities manager, compliance lead, or appointed contractor.
Do I need to shut down parts of my system during an investigation?
Not usually. Most investigations can be carried out while the system remains in normal operation. Only in severe cases - such as very high results or confirmed system misuse - would isolation or temporary restrictions be recommended.
How quickly should a Legionella investigation be completed?
Ideally within a few days of receiving results. HSE guidance expects duty holders to act promptly, and delays can allow further bacterial growth or increased risk. Titan Water typically completes investigations within 1–3 days depending on site size.
Can an investigation help prevent future Legionella problems?
Yes - a good investigation highlights weaknesses in system design, monitoring routines, or day-to-day operation. Addressing these prevents repeat failures and strengthens your overall water safety plan.
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​Visit our Learning Centre an explore a wide range of related articles to help you keep your water systems safe and compliant.
Explore Our Full Range of Services
Case Studies
When Legionella is detected, the root cause is almost always a mechanical issue. Our team here at Titan specialise in supporting our clients in 'engineering out' those issues that allow Legionella to proliferate.
Take a tour through our 'Legionella Remedial Works Case Studies' pages to explore some of the 700+ projects we deliver every year, offering a glimpse into the challenges we've faced and the innovative strategies our team have employed to deliver excellence for our customers.
Our Clients
Appointed on our reputation, retained on our results!
With over 75 years of water management experience, Team Titan have become trusted partners to some of the UK's leading corporate brands.
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