WATER HYGIENE AND SAFETY Pockets of warm water 60 l Percentage below required temperature 50 40
Such poor designs and installations had hampered the efficacy of the storage water temperatures in the control of Legionella, and had created significant pockets of warm water, where the trace amounts of Legionella that had managed to reach them were able to grow and proliferate.
30 20 10 0 14/1 to 31/3 1/4 to 5/7 6/7 to 10/8
Figure 2: Percentage of DHWS temperatures below required temperature. Date period (2014)
Site-level risk assessments and detailed root cause analysis exercises have revealed several technical issues that fall into each of these categories. A great deal of effort and expense has been expended on ‘fire-fighting’ positive Legionella spp. results by many healthcare organisations. However, it is important to now make more decisive actions for both the short- term and the medium term.
Case study 1
During 2014, I was commissioned to audit the management of water services at a large acute hospital that had six distinct principal water systems. The majority of the systems appeared to control Legionella adequately, but one in particular had experienced a significant increase in the frequency and count of positive Legionella sample results (see Fig 1) over a five-month period. I undertook a detailed root cause analysis of all events and activities associated with the water services during the previous 12-month period. Analysis of domestic hot and cold storage temperatures showed that these had been suitable during the period, with all storage temperatures being at the acceptable levels. However,
analysis of the water distribution temperatures showed a significant drop in compliance, beginning approximately 4-5 months earlier.
During the period there had been no significant change of use from the outlets. However, it soon became apparent what the contributory factor was – the area had undergone several quite significant alterations to the water pipework services, resulting in the creation of some preferential draw to certain areas, and reduced flow and distribution to others. Most notable was the decision to install several effectively very long legs of pipe, the longest of which was over 50 metres long.
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Most of the instances of increased Legionella growth in this case study could be linked back to the inadequate designs and installations
Most of the instances of increased Legionella growth in this case study could be linked back to the inadequate designs and installations. The Capital Projects team and contractors were all trained in accordance with HTM 04-01 Part A and Part B, and a set of minimum design standards was created. The problems have now been engineered out of the systems affected, and the site continues to receive good water quality.
Case Study 2
During 2013, I was commissioned to complete a similar root cause analysis of the increasing frequency of inadequate domestic hot water outlet temperature management at another large acute hospital. Here there were eight distinct principal water systems in use. Once again, most of the systems appeared to control Legionella adequately, but two had experienced a significant decrease in the percentage of adequate domestic hot water sentinel temperatures (see Fig 2) over the period April-August 2014. During this period domestic hot water temperature compliance had fallen from 92% to a level where just 50% of the outlet temperatures were compliant. I again completed a detailed root cause analysis of all events and activities associated with the water services during the previous 12-month period. The initial concern expressed by the client was that the outsourcing of the estates management service to a large service- provider approximately 11 months earlier had seen a reduction in the quality of service provided. However, the service- provider had the required management systems and planned preventive maintenance in place, and good
January 2019 Health Estate Journal 61
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