WATER HYGIENE AND SAFETY Figure 2a: post-flush bacterial data trend.
Second injection of ward and
New Cals installed
3000 2500 2000 1500 1000 500 0
strainer strip-outs – hydrogen peroxide
New tanks and booster system installed, new chlorine dioxide system in use
Post flush results
Anisa count SG1 count SG2-15 count
Spp count (not anisa)
restrictions applied by the manufacturer. These were set below the levels required for full pasteurisation. To compound the issues, one of the calorifiers was not achieving the temperature controls outlined in HSG 274 Part 2,2 or the Trust’s Water Safety Plan.
HTM 04-01,4 Post Feb 20 Post Mar 20 Post May 20 Post Jun 20
Post Jul 20
Post Feb 21
Post Mar 21
Post Apr 21
Post May 21
Post Jun 21
Post Aug 21
Post Sep 21
Post Oct 21
Cylinders fixed, new thermostat installed to CAL 1, new destrat pumps installed to CAL 1 and CAL 3, daily flushing, pasteurisation
Removal of
Injection Disinfection of Ward – Hydrogen Peroxide
Cylinders fixed, new thermostat installed to CAL 1, new destrat pumps installed to CAL 1 and CAL 3, daily flushing, pasteurisation – FEB 2020
New Cals installed – MARCH 2020
4500 4000 3500 3000 2500 2000 1500 1000 500 0
3rd Injection Disinfection of Ward – Chlorine
Clo2
dosing increased
plastic pipework and replace with copper
Full investigation into calorifiers A full investigation into the calorifiers discovered that these particular units could not be pasteurised without bypassing all the temperature and pressure control systems. Furthermore, the model that was installed was an old and discontinued product that had been specified and installed by the PPM contractor when previous cylinders reached the end of their useable life. The calorifiers clearly needed to be
Figure 2b: pre-flush bacterial data trend.
New tanks and booster system installed, new chlorine dioxide system in use
Pre Flush results
Anisa count SG1 count SG2-15 count
Spp count (not anisa)
replaced with units correctly specified for the site, as a priority. The result was that a capital expenditure that had been allocated for moving cold water storage tanks out of a 25 metre-high water tower had to be spent on replacing the current calorifiers with new calorifiers capable of delivering thermal control – the primary control measure used by the site. Sadly, the calorifiers were not initially
Pre Jun 20 Pre Jul 20 Pre Feb 21 Pre Mar 21
3rd Injection Disinfection of Ward – Chlorine
Injection Disinfection of Ward – Hydrogen Peroxide
Second injection of ward and strainer strip- outs – hydrogen peroxide
contact time due to the size of the system. Following the systemic disinfection, and in line with HSG274 Part 2,2
paragraph
2.132, sampling was undertaken two days post-systemic disinfection to measure the impact of the process. The first set of post- disinfection samples showed no positive results in either the hot or the cold water system. The second round of post-disinfection sampling was undertaken in January 2020. The system returned negative results for all of the cold system. The hot system, one month after a set of ‘not detected’ post disinfection results, had numerous positive results, indicating that some form of systemic issue remained in the hot water system.
Meeting with Estates team The disinfection not resulting in the desired outcome led to a meeting with Lakeside’s client and its tenants’ Estates team. At the meeting it was discovered that three calorifiers were operating at between 38-42 °C, a fault not noted during the
22 Health Estate Journal March 2022 Clo2
dosing increased
Removal of
plastic pipework and replace with copper
disinfection process due to the requirement to work on a ‘cold’ system in order to prevent the chemical from being oxidised off during the disinfection process. There was no evidence in the site log books or records of monthly monitoring of these assets by the incumbent PPM contractor appointed to undertake this task. It was therefore unclear how long these assets had been operating in the peak zone for Legionella growth, as set out in ISO117313
for Legionella culture plates. With an initial clear cause for Legionella ‘‘
growth identified, a programme of daily flushing was instigated, with every asset on the hospital site included, while the calorifiers were repaired. However, on further investigation it was identified that these calorifiers had temperature
Pre Apr 21 Pre May 21 Pre Jun 21 Pre Aug 21 Pre Sep 21 Pre Oct 21
installed correctly by the plumber. Some deadlegs were created when non- flow-through expansion vessels were incorrectly installed. This was highlighted by the temperature monitoring staff as part of the ongoing daily flushing at the site. Once rectified by the installer, a full pasteurisation of both the water storage and distribution system was undertaken. Had this installation been undertaken by an LCA-registered company then one would have expected a more competent installation, due to having audited management procedures and processes for such installations. The full system was temperature monitored, via the ongoing daily flushing of the site, for a six-week period. The ongoing monthly sampling following new cylinder installations showed that the hot water system now had no positive Legionella results across the site, apart from one ward.
The ward where Legionella didn’t die With the systemic issues resolved, focus was now placed on a single ward. This was flagged as an issue, as it repeatedly provided positive Legionella results in the hot water monitoring programme despite the rest of the site now delivering four consecutive ‘not detected’ Legionella results in the hot and cold water systems. The first approach from Lakeside Water
With an initial clear cause for Legionella growth identified, a programme of daily flushing was instigated, with every asset on the hospital site included, while the calorifiers were repaired
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