Les Szabo, NSW (New South Wales) State manager at Australian water treatment specialist, HydroChem, discusses work to implement an effective Legionella risk management and prevention strategy for the hot water system at a Sydney hospital. Among the key steps taken to address the existing protocols’ shortcomings were establishing a proper sampling protocol, implementing a monthly maintenance programme for chlorine dosing, taking samples from locations on each floor – with a focus on showers, and installing a chorine dosing unit equipped with remote telemetry.
installing a chorine dosing unit equipped with remote telemetry. Legionnaires’ disease, and the control of Legionella bacteria in potable water systems, are challenges particular to healthcare facilities for two main reasons:
1 Hospitals require the delivery of warm water for the use of patients at handbasins and showers.
2 Patients in hospitals have a higher risk of developing illness than the general population.
Hot water delivered from either instantaneous or stored water boilers is usually maintained and delivered to outlets at approximately 60 °C. At this temperature there is a risk of scalding. As a result, it is a general requirement in hospitals that the water delivered at outlets is mixed with cold water to deliver water at a temperature no higher than 45 °C.
A difficult balance
Unfortunately, maintaining water at a safe level to prevent scalding is the ideal temperature to promote the proliferation of Legionella bacteria. The genus Legionella, which comprises over 50 different species, has evolved to survive in the natural environment in soil, rivers, and lakes. Legionella cannot fulfil its lifecycle without invading a host, taking nutrients from the host, and then multiplying. Typically, a warm, swamp-like environment is the ideal location where Legionella can multiply in the presence of other microorganisms like slimes and amoeba.
While in nature, the temperature variations between seasons and overnight help to mitigate the rate of bacterial multiplication, in our highly controlled environments we often create a constant temperature range that is perfect for certain microorganisms. Legionella will generally remain dormant below 20 °C, and will die above 60 °C. The ideal temperature for proliferation is the same as the target temperature for warm water systems.
Given that Legionella have evolved over millions of years, and survive in the natural environment, it is highly likely that most of us have been exposed to the bacteria without becoming ill. Legionnaires’ disease is predominantly identified in patients with weakened immune systems or other underlying health conditions. The proximity of such patients in the hospital environment increases the likelihood of an outbreak should the bacteria contaminate the water distribution system.
Compliance
The control of warm water to prevent scalding is mandatory in all states and territories of Australia. The regulators recognise the increased risk of Legionella bacteria and, as a result, water hygiene within the hospital environment is also either regulated or stipulated through guidelines issued to the healthcare industry, including aged care facilities. For operational managers within healthcare facilities, one of the major impetuses for taking steps is the requirement to ensure compliance with regulations, to the letter of the expectation. Prima facie, this will satisfy the duty of care, and mitigate any claims of negligence. In my experience, the first step taken by operational managers is often seeking to meet the requirements stipulated. At times, this step is taken without the understanding of how each individual component fits together to achieve an outcome
Case study
I will now step you through a case study involving a small Sydney hospital with a recirculating warm water system, where the aforementioned approach resulted in the following actions being implemented:
A Legionella risk management plan (RMP) developed by a general ‘corporate-style’ risk management firm.
A chlorine dosing unit installed on the warm water system.
Sampling initiated with an independent party
Prior to having the risk management plan prepared, the hospital had engaged an independent microbial testing contractor to take samples and analyse for Legionella and the Heterotrophic Colony Count (HCC) of the water distribution system. As there was no formal sampling protocol to follow, this resulted in:
The water sampling technician taking samples from the most easily accessible outlets – as opposed to those identified as a higher risk.
An inordinate number of samples being taken from basins, that present a relatively low risk of dissemination compared with showers which may produce aerosols (which can be inhaled).
An unwarranted focus on HCC – which does not present a Legionella health risk per se, and is not stipulated as mandatory.
In addition to the testing undertaken by the independent contractor, the Health Department undertook periodic sampling and testing on an unannounced frequency. The hospital was receiving positive Legionella detections at every round of testing by either party
Disinfection system maintenance
The hospital installed a chlorine dosing system purchased through the HVAC water treatment contractor. The unit was provided by a reputable manufacturer, and was being maintained by the hospital’s ‘in-house’ plumber. With reduced staffing levels, and lack of training or support, this meant that the dosing system was often going into fault due to blocked injectors, chemical dosing tanks running empty, ORP probes not calibrated, and dosing pumps losing prime.
To keep the system operating, the supplier recommended a new chemical dosing pump be installed, although the existing pump was still operating correctly. This resulted in the purchase of a piece of equipment which was not necessary. Unfortunately, this did not solve the issue that there was no continuous or reliable source of chlorine being dosed to the system. Effectively training staff on how to overcome a loss of prime, or cleaning the injector using a weak acid, may have gone some way to rectifying the loss of disinfection.
The water supplied to the hospital is via Sydney Water mains delivered to the site boundary before being held in two bulk storage tanks. The RMP contained a photo of the storage tank and a schematic of the plantroom with no legend. There was no critical assessment of the arrangement.
Despite attempting to satisfy the requirements of local regulations, the outcomes for the hospital were poor. That is, the sampling of outlets continued to return both high HCC and adverse Legionella detections. We can break down the simplified process described above to address Legionella risk as a flow chart, shown in Figure 1.
When asked to review the current RMP and outcomes at the hospital, we first noticed something very common in the industry. The actual order of actions undertaken did not follow the flowchart. In this instance, the sampling occurred first, followed by the installation of a chlorine dosing unit in response to poor results, and only recently had the RMP been completed. One may describe this approach as putting the ‘cart before the horse’. It is a common occurrence, as facility managers are trying to satisfy all the requirements of the regulations in one fell swoop.
At this hospital, the problem was further compounded by the fact that each action was undertaken in isolation, without strong lines of communication. The proper implementation of the required steps fell through the gaps. The gaps occur at the arrows of the flow chart, and are a result of each party lacking ‘skin in the game’.
Review of the RMP document
HydroChem was engaged in March 2022 to review the RMP document competed in October 2021. The remit was to improve the outcomes of testing, being the poor Legionella detection rate. A new RMP was not commissioned, so HydroChem provided a desktop review of the RMP, as well as a site audit to review the dosing equipment and sampling protocols.
The RMP developed by the firm comprised 30 pages, the first full page being a statement of limitations – the focus of which was acknowledging that the firm was relying on information provided by the client, and that it accepted no liability for completeness. The completion of remedial actions was not verified by the RMP. There were no records of responses to high Legionella or HCC detections prior to retests.
The document listed several hazards to investigate, which are available from the guidance material provided by regulators. However there was very little in actual validation of the current state of each hazard at the hospital. Moreover, most of the recommendations were motherhood statements highlighting that the hazard ought to be reviewed and considered.
There was no empirical data establishing:
The current mains water system supply and water quality.
The efficacy or maintenance of the chlorine dosing system.
A suitable sampling protocol.
The RMP recommended that suitably qualified contractors be engaged to determine the aforementioned items.
Gap 1: Sampling Protocol
HydroChem commenced the review by addressing the generic recommendations of the RMP. A site audit was undertaken, and a detailed schematic of the water distribution system prepared – see Figure 2. Testing of the mains water and storage tanks revealed that there was nil disinfectant being maintained in the storage tanks. Although Sydney Water treats mains supply water, the level of disinfectant at the boundary will vary depending on the distance from the treatment plant, as well as the condition of pipework leading to the building. Storage tanks will also allow the water to sit idle and dissipate the free disinfectant level over time. Any fouling in the tanks may contribute to the presence of bacteria.
Interestingly, the Australian Drinking Water Guidelines do not provide a limit for either Legionella or HCC, meaning that Sydney Water does not provide testing of these parameters
The independent contractor was sampling 10 locations per month. However, due to the lack of a sampling protocol, these were taken from ad hoc locations. It was also common for the handbasins to be tested. This is often the case, as it is easier for a water sampling technician to take a basin sample because they are less likely to get wet, or indeed to bother patients, in the process.
HydroChem suggested that a protocol of eight samples per month would meet the local regulatory requirements, and provided a satisfactory overview of the water distribution system health.
HCC testing could cease, as this is not mandatory in New South Wales, nor according to the EnHealth guidelines (which are generally accepted as ‘best practice’). HCC sample results and followup actions detracted from the major hazard – Legionella. Furthermore, the sampling protocol ought to be distributed across all floors, and focused on showers, rather than basins.
Handbasins do not present a risk of creating aerosols – a pathway for infection. Most people only utilise handbasins for a few seconds, which means that the water may be stagnant for extended periods. By comparison, showers are commonly operated for at least 5-10 minutes, flushing sufficient water to allow the residual disinfectant to take effect. Handbasins tend to form significant biofilms at the outlet and at the aerators, giving a false representation of the wider recirculating system. Accepting that healthcare providers (as most industries) have competing financial pressures, our goal was to get the ‘best bang for the hospital’s buck’. Funds spent taking more samples than needed, and testing for something unnecessary, were better redirected toward other measures that helped in achieving acceptable Legionella results.
Gap 2 – Providing disinfection to the warm water system
Reviewing the hospital’s chlorine dosing system revealed that the unit was not calibrated. This meant that despite showing sufficient disinfectant levels, there was nil chlorine present in the recirculating warm water. This loop, at 45 °C, was the ideal location for the multiplication of bacteria. It also should be relatively simple to treat, as it is essentially a closed loop. The site plumbers had little training or support in the operation for the dosing system. This meant that attempts to adjust the system were unsuccessful. We also identified that the sampling probe and injection point were installed sub-optimally. The probe was reading water coming from the water heaters, and the chlorine was injecting disinfectant prior to the heaters. This resulted in a ‘false’ loop. Chlorine tends to ‘flash off’ and become inactive when heated, meaning that the probe was reading a reduced level of chlorine, which in turn dosed more chlorine into the heating loop. Simply switching these two locations meant that the probe could read the level of disinfectant circulating in the water distribution system through the hospital returning to the dosing unit, and then dosing chlorine on its departure from the heater and leading back through the hospital. The result was an improved level of control through the outlets, and a quicker response by the probe
Given that the hospital plumbers had experienced several situations where the chlorine tanks had run empty or the pump had lost prime, a unit with remote telemetry was proposed. While still retaining the existing dosing pump, a controller was installed that allowed alarms sent via SMS or email. This meant that any failure in the treatment system could be identified immediately, and steps taken to rectify them quickly. HydroChem was engaged to undertake monthly services of the chlorine dosing system, reducing pressure on the site staff, and ensuring that the system was calibrated and operating properly.
Gap 3 – Focusing on high-risk outlets
Sampling was adjusted to focus on showerheads, and to distribute the samples across all floors of the hospital. Monthly testing revealed that there was a delay in the movement of the treated warm water to all outlets, and hence a reduced level of chlorine in some areas. This was relayed to the Engineering team for review. Plumbers were engaged to balance the control valves throughout the system to ensure that water flow is shared equally across the whole system.
After the review several steps were implemented, and in summary these included:
Implementation of a monthly maintenance programme for the dosing system commenced in July 2022.
Reversing the dosing point and probe sampling point.
Ceasing testing for HCC.
Taking samples from locations on each floor and focusing on showers.
Testing free chlorine at each outlet during sampling.
Installation of a dosing unit equipped with remote telemetry
Following these changes, the hospital had 10 months of nil Legionella detections. Chlorine was maintained at all outlets, even when utilising the older controller. The site staff were able to contact HydroChem when they noticed any issues on the controller display and prompt a service visit to rectify.
A new dosing controller was installed recently which allows the disinfection system to be reviewed from a computer or mobile phone, as well as receiving alarms when the levels drop below a critical point. The Engineering Department receives these alarms as do HydroChem. Disinfections can be initiated remotely as a remedial action prior to retests. Figure 3 shows a history of the disinfectant levels at the hospital
Forming trusting relationships
Probably the most effective change in the Legionella risk management process at this hospital was the way in which HydroChem was engaged with a clear remit. From the viewpoint of the Engineering Department, they had satisfied the requirements of the local regulations in a general sense, although there were ‘gaps’ between each of the mitigation steps.
When invited to review the process, HydroChem was given a very clear remit: ‘Reduce the number of Legionella detections”.Given that we had prior experience with people working at the hospital, it was not lost on us that HydroChem had to deliver a result. Strong relationships and maintaining a good reputation are paramount in our industry. I would not have accepted the project if I did not have confidence that we could affect a successful outcome. My confidence is built on real-world experience, and an in-depth knowledge of controlling Legionella bacteria in plant water circuits. We have no choice but to put ‘skin in the game’ coming in at this point of the process.
Getting the most from your Legionella management process
Some simple steps that will help achieve satisfactory control of Legionella include:
Start at the beginning. Have a risk management plan completed.
When choosing a provider, ask for references for the individual who will be walking the floor of your facility. Make sure that the person engaged to conduct the risk management plan is a water hygiene expert – as opposed to someone who provides generic risk management advice across broad categories of knowledge.
Request a detailed scope of deliverables – not merely ‘in accordance with a standard’. Make sure it includes the elements you will need, namely an assessment of the incoming water, a schematic of the hot, cold, and warm water systems, and a sampling protocol. There is plenty of guidance material available, and good consultants will help point it out.
Engage an experienced water treatment provider for any disinfection work. Look at its prior experience in dealing with potable water treatment specifically, ensure its involvement beyond simply inspecting the site every month, and make sure that it will be there when things go wrong.
Whether you chose to sample ‘in house’ or engage a sampling/ laboratory provider, make sure you have familiarised yourself with the recommended methods and follow them. Again, a good consultant or water treatment company ought to be able to provide guidance.
Keep in regular communication with the people managing each step. There should at least be a quick review of actions and results each month. You should speak with your sampling and water treatment provider at each service. Ideally the RMP consultant should be included periodically. Confusing compliance with risk management when trying to tame an invisible beast is fraught with risk.
Acknowledgment
This article, titled ‘Legionella in warm water systems – Taming an invisible beast’, was first published in the December 2023 issue of Healthcare Facilities, the official journal of the Institute of Hospital Engineering, Australia, and was produced from the Institute’s National Conference 2023. HEJ would like to thank the author, the IHEA, and the magazine’s publisher, Adbourne Publishing, for allowing its reproduction in slightly edited form here. Thanks also to Iceberg Events for helping facilitate permission to publish the article