Water quality

SA Health and SA Water work cooperatively to ensure the continued protection of public health in relation to the supply of drinking water across the state. SA Water complied with all requirements under the Safe Drinking Water Act 2011 including the notification of incidents under the interagency Water/Wastewater Incident Notification and Communication Protocol.

During 2022-23, SA Water conducted 46,089 tests for analytes in drinking water supplies throughout the state for compliance with the Australian Drinking Water Guidelines (2011) (ADWG). These results were reported to SA Health in line with agreed reporting protocols. Compliance with the ADWG for E. coli was achieved in 99.97 per cent of metropolitan Adelaide samples and 99.96 per cent of regional samples. Overall compliance with the ADWG for health-related parameters was 99.98 per cent for metropolitan systems and 99.85 per cent for regional areas.

The total number of incidents notified by SA Water during 2022-23 (179) was higher than in 2021-22 (136) but most of this was due to an increase in Type 2 incidents. There were 2 Priority Type 1 incidents during 2022-23 for enteric protozoa detected in treated water samples. Both of these incidents were managed appropriately to prevent risks to drinking water quality.

The impact of the River Murray flooding event in December 2022 resulted in an increase in incidents particularly related to elevated levels of cyanobacteria, and physical parameters such as high turbidity. The flood waters contributed to overall poor water quality in the River Murray resulting in treatment and disinfection challenges at water treatment plants fed by River Murray water. Incidents relating to disinfection by-products also increased.

High rainfall events led to a significant increase in the detections of enteric protozoa (Cryptosporidium and Giardia) in drinking water catchments and source waters. There were 42 Type 2 incidents involving detection of enteric protozoa in the catchment following rain events or at the inlets to drinking water treatment plants. No faults were detected from the continuous monitoring of treatment plant performance during the periods when the protozoa were detected in the source water.

The number of incidents (9) related to recreational use of reservoir reserves was lower than in 2021-22 (20). The incidents did not have a measurable impact on drinking water quality.

There was a small increase in the number of detections of E. coli in drinking water samples in 2022-23. Appropriate remedial action was taken to minimise the impact to public health. Overall compliance of E. coli monitoring remained very high.

All water quality incidents were notified by SA Water in a timely manner. Appropriate remedial actions and responses were implemented following incidents to ensure the protection of public health was maintained at all times. No incidents required public notification during the reporting period.

The 85 drinking water supplies we operate serve customers across metropolitan and regional South Australia. This year we have merged what was previously reported as country and remote Aboriginal communities into one category (regional).

To maintain quality, we have SA Health-approved drinking water quality monitoring programs with samples collected and analysed throughout all aspects of the water supply system, including catchment and source water, treatment processes, and the distribution network up to the water meter on individual properties.

We monitor for health and aesthetic compliance and to optimise water quality. Samples are collected by our trained field workers to make sure they are taken correctly, and field results have a high degree of integrity. Laboratory analyses are carried out by our Australian Water Quality Centre in accordance with ISO 9001 Quality Systems and NATA requirements.

In 2022-23, we demonstrated robust management of water quality by consistently providing safe, clean drinking water to our customers despite the challenges posed by the flood event in the River Murray.

Percentage of routine results at customer tap sample locations within drinking water systems which comply with the ADWG health limits (including E. coli).

Direct exceedances of the ADWG were used rather than the 95th percentiles for compliance of individual chemical parameters.

Prior to calculating per cent compliance for health-related chemicals, individual results are rounded to the same number of significant figures as the guideline value in the ADWG (as prescribed in the ADWG and agreed with SA Health).

We analysed 46,089 test analytes from our drinking water supplies (customer tap sample locations) throughout South Australia to determine health-related compliance. We achieved 99.96 per cent E. coli compliance across customer tap sample locations with exceptions in one metropolitan and 3 regional systems. Compliance with ADWG health-related parameters across customer tap sample locations was marginally below target at 99.89 per cent. This result can be largely attributed to the flood event which saw a short-term rise in disinfection by-products in several of the systems fed directly from the River Murray.

Although we aim for 100 per cent compliance all the time, the ADWG recognises that occasional exceedances may occur with most guidelines for chemicals based on a lifetime of exposure. In accordance with the guidelines and the interagency Water/ Wastewater Incident Notification and Communication Protocol, all detections were immediately communicated to SA Health, investigated by us and corrective actions implemented as agreed with SA Health.

SA Health has confirmed that drinking water provided to customers by us was safe and that appropriate responses and corrective actions were implemented for all exceedances and these mitigated any risks to public health.