HC Legionella is a water hygiene specialist focused on resolving Legionella control issues. Here, authorising engineer Claire Jackson shares an example of her team’s work in addressing temperature issues at a high-risk site that posed a threat to vulnerable individuals
HC Legionella is a water hygiene specialist who is an expert in resolving Legionella control issues. We don’t just say we manage through to resolution; we live it. Our knowledgeable team includes an authorising engineer and expert plumbers. This means you get an industry expert looking at your challenges while our plumbers can give you the mechanical mindset to resolve any issues.
A Legionella control issue can be as simple as a non-compliant water temperature. Still, the root cause behind this loss of control can range from a lack of insulation on the pipework to full-on mechanical failure of a circulating loop. No matter the problem, we will work with your estates team to resolve the matter.
On a recent project, HC Legionella was called upon to provide our expertise when the estates team identified a building with temperature issues on a high-risk site with highly susceptible people. Our team mobilised within moments of taking the enquiry and arranged to meet the estates team on site the following morning. In the meantime, past site data was shared with our AE to gain a broader understanding of the site and plot a plan of attack with our lead plumbing engineer.
Upon reviewing the site records, it was clear that something had been going wrong on this site for some time. At this point, the key focus of the HC Legionella team is to protect patient safety, and the discussion turned to initial risk mitigation through the use of Point of Use (Pou) filters. These units break the infection pathway at the outlet to stop any waterborne pathogens, be that Legionella, Pseudomonas or other pathogens, from coming into contact with patients. Providing the perfect short-term risk mitigation solution while the site is investigated, PoU filters were deployed here to give us time to review the system, records, and risks and investigate. Risk mitigation gave us time to develop a plan and root for a solution.
Before installing the PoU filters, the HC Legionella approach meant that we took some Legionella samples (to confirm if the hazard had come to pass) and submitted them to our UKAS-accredited laboratory for testing. This process takes ten to 12 days from receipt to reporting. We understand that testing takes time; if a site requires three negative results to be signed off, then this can take between 45 and 55 days; build in weekends, time to meet and discuss the next steps, then it’s clear to see how 90 days can quickly come to pass.
The plumbing team installed the PoU filters within a couple of days. The time afforded by installing PoU filters gave us respite; the infection pathway was broken, and we had 90 days of protection to investigate the system.
We had already taken pre and post flush Legionella samples to identify the extent of the infection throughout the system, and we could start to look for root causes of issues and be proactive in managing the situation. Until this point, our role was to make the system safe. We can do our best to regain control and manage through to the correct resolution for our client.
Post filter install, we undertook a site-wide temperature profiling exercise and confirmed where control was lost and identified some potential sources of failure, including:
- Poorly performing subordinate loops;
- Less than optimal pumps; and
- Several dead legs.
We were heading down a pathway to a phased resolution for Legionella control
Phase one was easy; all identified dead legs on site were removed, some on the hot, some on the cold system – reducing the risk on both systems and giving the client some assurance that positive progress was being made with reducing risk. The original data search and temperature profiling identified several Thermostatic Mixing Valves (TMVs) that did not have a complete service history recorded, resulting in out-of-specification performance temperatures. These were fully serviced and reinstated, again showing progress on site and positive, proactive steps to reduce the risk and work to a resolution.
The laboratory reported their results as we planned our next steps; this identified a cluster of results delivering >15,000 CFU/L counts of Legionella bacteria present. We were not out of the woods, but we had already made significant progress in removing dead legs and servicing some TMVs while gaining our full temperature profile of the site. With our failing lab results falling on the hot system, we knew where the hazard had come to pass; we knew it was isolated to the hot water system, and we had a strategy to resolve the issue.
Our AE, in discussion with our mechanical plumbers, noticed that when the site was first commissioned, it had ten bedrooms; this had been extended over the years, with pipework tacked on to allow for bathrooms, toilets and en-suites. Within these building changes, the pipework for the flow and return system had been significantly downsized to feed the extension, with flow pipework reducing from 42mm to 22mm, where it was connected to the existing system. This meant that the flow and return pipework were now undersized in an area of the builiding, resulting in lower flow temperatures and poorer returns. This change in pipe size was also found to correspond precisely to the area of the building with significant positive Legionella results. Theoretically, we had a resolution.
With the site’s agreement, the hot water supply was removed for a weekend to allow the work to occur. The flow pipework was the first part of the project, increasing from 22 to 42 mm copper. Once this was completed, we upgraded the return from 15 to 22mm copper pipework. Having taken all of the Saturday to complete the flow pipework installation and cut the returns, we had the Sunday to:
- Install the return leg;
- Reset the boiler;
- Check the pumps; and
- Ensure that the works had the desired effect on the circulation capability of the system.
Flushing all outlets and taking updated temperatures demonstrated that the system was operational again; this first challenge was completed. Our temperature profile of the flow and return showed that, even with excessive use, the hot water temperatures at the boiler had improved to a compliant level. To verify this, we took temperatures at all outlets, pipework temperatures (from the hot and cold feeds) for the TMVs, and temperatures of subordinate and tertiary loops to verify that the system was working and achieving compliant temperatures throughout.
The system was monitored over the next three months, and the PoU filters were removed after a third set of Legionella samples delivered non-detected results to verify that the hazard was removed. Regular review meetings were conducted with localised action groups, including estates, compliance, and infection control, to ensure that the resolution was adequate and the work was satisfactory; the work was signed off – a true example of effectively managing an issue through to resolution.
