Notifying the Regulator

Under sections 102 and 102A of the Water Supply (Safety and Reliability) Act 2008, Council is required to immediately inform RDMW if the quality of water supplied from the drinking water service does not comply with the water quality health criteria as specified in the ADWG, or if Council becomes aware of an incident as prescribed under a regulation. Council made five notifications to RDMW during the reporting period, summarised in Tables 34-37 below.

Table 34: Boil Water Notice at Mirriwinni due to water shortage event.

Boil Water Notice for Mirriwinni due to water shortage Scheme Parameter Incident date Regulator notified Event description

Corrective and preventative actions Mirriwinni NR 23/12/2020 – 31/12/2020 23/12/2020 | 11:50 AM Water demand in the Mirriwinni scheme had increased to greater than the rate that water could be produced causing a decline in reservoir storage level. To avoid running out of water, production rate needed to be increased and sourcing water from neighbouring schemes was not a viable option, therefore a planned removal of bag filters from the Mirriwinni treatment system took place (pre-filtering, UV and chlorine disinfection remained in place). A pre-cautionary Boil Water Notice was issued for the scheme on 23 December 2020 while the bag filters were not in place, though no water quality issues were identified throughout the event. Sampling in the reticulation system was conducted once the bag filters were reinstated and before the Boil Water Notice was removed to ensure E. coli met the guideline value of <1 CFU/100mL. Both samples collected met the guideline value which led to the Boil Water Notice being lifted on 31 December 2020 while Level 1 water restrictions remained in place for a period of time to prevent the issue from occurring again. Various work is underway or planned to prevent this type of event occurring in the future including leak detection, mains replacements, possible filter upgrades pending trial results, and a rural water security planning study for the future.

Table 35: E. coli incident in Trinity Park

E. coli detection in Trinity Park Scheme Parameter Incident date Regulator notified Incident description

Corrective and preventative actions Copperlode/Behana E. coli 05/01/2021 06/01/2021 | 5:08 PM Estimated 1 CFU/100mL E. coli was detected in a routine verification monitoring sample at sampling point on Roberts Drive Trinity Park. The chlorine residual at the time of sampling was 0.73mg/L Free Chlorine and 0.78mg/L Total Chlorine and all other parameters tested were compliant. Chlorine levels at the sampling point and the feeding reservoir were investigated finding that disinfection was normal. Potential causes such as main breaks were investigated and none found. Two follow up samples were collected on 6th and 7th January which both tested <1 CFU/100mL E. coli complying with the E. coli guideline value. Due to this no further actions were taken and it was noted the most likely cause was environmental contamination of the sample from rainfall at the time of sampling.

Boil Water Notice for Bartle Frere due to water shortage Scheme Parameter Incident date Regulator notified Incident description

Corrective and preventative actions

Table 37: Chlorine exceedance in Forest Gardens Bartle Frere NR 02/03/2021 – 11/03/2021 02/03/2021 | 11:11 AM The event was triggered by weather associated with Cyclone Niran which impeded water production rate by increasing raw water turbidity, in turn the increase in turbidity caused an increase in demand on the town water supply. Alongside pre-established leaks in the system and power and communication issues with SCADA due to the weather, the water reservoir dropped to critical levels and production rate needed to be increased to avoid running out of water, therefore a planned removal of bag filters took place (UV and chlorine disinfection remained in place). A pre-cautionary Boil Water Notice was issued on 2 March 2021 for the scheme while the bag filters were not in place. A sample collected while the filters were removed found that colour and turbidity were elevated however no health guidelines were exceeded. Sampling in the reticulation system was conducted once the bag filters were reinstated and before the Boil Water Notice was removed to ensure E. coli met the guideline value of <1 CFU/100mL. Both samples collected met the guideline value which led to the Boil Water Notice being lifted on 11 March 2021. Various work is underway or planned to prevent this type of event occurring in the future including leak detection, mains replacements, possible filter upgrades pending trial results, and a rural water security planning study for the future.

Chlorine exceedance in Forest Gardens Scheme Parameter

Incident date

Regulator notified Incident description

Corrective and preventative actions Copperlode/Behana Chlorine

25/05/2021

25/05/2021 | 9:14 AM

A free chlorine result of 5.6mg/L (5.9mg/L total) was measured in the reticulation network at Forest Gardens - Monsoon Terrace verification monitoring sampling point. Chlorine concentration in the feeding reservoir where chlorine was dosed was normal in the period leading up the exceedance, though verification monitoring also detected elevated chlorine in the reservoir. The Regulator was notified as further investigation was done to determine why the sample exceeded. The sampling site, feeding reservoir and other sites in the same reservoir catchment were tested for chlorine, finding concentrations were normal. Investigations concluded the issue was caused by faults with the use of the chlorine meter used to test the sample, therefore the elevated results were anomalous and there was no risk to public health.