https://www.wmsoc.org.uk/knowledge/publication/262
On 13 May 2024, the Water Management Society published the second part to its guidance on the use of remote monitoring technology. Remote monitoring, for those that may not know, involves the use of small temperature probes attached to the pipework and taps of water systems that allows temperature readings to be taken without the need for someone to be there in person to measure them using a thermometer. Importantly, the probes are able to detect temperature changes across the water system that provide information, not only on the temperature of the water but, on whether water is flowing through the system and when water outlets are used.
he new guidance is intended to help those who have decided to use this type of technology to interpret and manage the often voluminous amount of data that these systems generate, and follows on from Part 1, published in January 2023, which was intended to explain some of the advantages of using this technology and the things that should be considered when deciding whether or not to adopt it.
Both pieces of guidance were produced in conjunction with colleagues working at the Health and Safety Executive (HSE), and with contributions from our Technology and Consultancy Director, Rob Nicoll, and our Technical Director, Paul McDermott
Amongst other things, Part 2 explains how remote monitoring technology can assist in the process of conducting risk assessments for Legionella in hot and cold water systems – their use provides valuable information on the ways in which water systems operate day-to-day over prolonged periods, which is something that conventional approaches to this type of risk assessment usually lack.
Once installed, the importance of these systems in the overall scheme of control for the water system is discussed, highlighting the ability of the technology to detect changes that occur in the water system and its use that might otherwise go unnoticed. Where necessary, this can allow remedial actions to be taken in a timely way, e.g., identifying water outlets that require flushing to avoid risks due to stagnating water, and areas of low, or no, flow of water within a system that could also lead to stagnation and the growth of Legionella to harmful levels.
Because these systems operate continuously, they generate significantly more data on the usual functioning of water systems than was previously possible using conventional manual approaches to monitoring. The new guidance gives advice on how users of the system, including service providers like ourselves at HSL, can manage the volume of information generated and advises on how alerts should be set to avoid information overload.
Perhaps most significantly, the guidance signals a seed change in the way the safety of water systems should be monitored, moving away from a reliance on simply measuring water temperatures at tap outlets, where the temperatures reached might be achieved artificially by running the outlet for a period that is often longer than when the outlet is opened in normal use. The new guidance emphasises the importance of movement of water within a system as a key factor in control, as well as temperature when appraising the overall safety of the system.
At HSL, we are at the forefront of remote monitoring technology and our remote monitoring arm of the business, Plexus Innovation, is already applying these principles in the delivery of this technology to our customers.
https://www.hse.gov.uk/pubns/priced/hsg274part1.pdf
In March 2024, the HSE revised and reissued its technical guidance on managing risks from Legionella arising from the operation of evaporative cooling systems, such as cooling towers and evaporative condensers. This new edition replaces the now superseded version published in 2013.
There are some notable new elements to the guidance, perhaps most important being additional advice on a reagent called DPD No 1, which is used commonly to measure and monitor the concentration of halogenated biocides used to control microbial activity, including the growth of Legionella, in these types of systems. The new guidance advises on the effect that pH can have on the levels of active biocide present in the water and therefore its potency in controlling bacterial growth.
There is also additional information on the application of new and emerging technologies in the control and detection of Legionella in evaporative cooling systems. For example, the new guidance provides some advice on the use of ‘hydrodynamic cavitation’ as a control measure used instead of, or in conjunction with, conventional application of biocides. Although used rarely in the UK, hydrodynamic cavitation relies on the installation of a device that causes local reduction in water pressure that causes tiny bubbles to form which then increase in size before collapsing violently, apparently killing bacteria in the process.
In addition, new techniques for the detection of Legionella in cooling system water using a molecular genetic technique, known as polymerase chain reaction (PCR), are discussed. The advantage of PCR over conventional culture techniques is that results of testing are available in less than a tenth of the time, allowing remedial actions to be taken more quickly when needed. There are disadvantages to the use of PCR, however, not least the difficulties in interpreting the results. This is because PCR and culture methods measure different things and the current action levels given in HSG274 Part 1 are geared towards the latter, rather than the former. There is also some additional guidance on the limits of detection of different variations of the conventional culture method, i.e., how sensitive these are in detecting Legionella in cooling tower water samples.
Important health and safety advice when sampling cooling systems in high-risk situations, e.g., during an outbreak investigation, or from systems that have yielded high Legionella counts previously, is included in the 2024 guidance, along with the need for assessing the risk in such situations to ensure additional control measures are used when needed.
The changes to the guidance have been discussed at our Health and Safety Committee and Technical, Environmental and Quality Committee meetings and we are making sure that, where these are relevant to the services we provide to customers operating evaporative cooling plant, these are incorporated into our method statements and that appropriate advice is given to our customers.
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