Drinking Water Quality Risk Management Plan

Purpose. This plan identifies the hazards to drinking water quality from catchment to tap, assesses the risks, and sets the preventive measures, critical control points, monitoring, incident response and improvement program required by the Safe Drinking Water Act 2003 (Victoria).

1.System description

The Kialla supply draws river water through a screened offtake to a raw water storage dam, then through the Kialla plant (coagulation, clarification, dual media filtration, hypochlorite disinfection, fluoridation, lime pH correction) to a clear water storage and 14 service reservoirs supplying eight towns. The northern supply draws groundwater from a bore field, disinfects with hypochlorite and supplies three towns through five reservoirs. Both systems are monitored from the control centre.

2.Hazard identification

The hazard register lists microbial, chemical, physical and radiological hazards and the hazardous events that can introduce them at each step. The highest rated hazards are pathogens from catchment stock and septic runoff after rain, blue-green algae toxins in the storage in summer, filtration breakthrough after backwash, loss of disinfection from pump or analyser failure, backflow from unprotected commercial connections, and contamination during mains repair.

3.Risk assessment matrix

Risks are rated by likelihood (rare, unlikely, possible, likely, almost certain) and consequence (insignificant, minor, moderate, major, catastrophic) with public health as the primary consequence measure. Very high and high residual risks must have a critical control point or an equivalent preventive measure with monitoring. Medium risks are managed through procedures and verification. Low risks are reviewed annually.

4.Preventive measures and critical control points

Catchment surveillance, the storage dam as a buffer, algae monitoring and offtake depth selection, coagulation, filtration, disinfection and reticulation residual are the preventive measures. Coagulation, filtration, disinfection at both plants and reticulation residual are the critical control points recorded in the Critical Control Points Register with their limits and corrective actions. Backflow prevention devices on medium and high hazard connections are tested annually.

5.Operational and verification monitoring

Operational monitoring is continuous online for turbidity, chlorine, pH and fluoride with alarms to the control centre and shift bench tests. Verification monitoring collects samples for E. coli, disinfection by-products, fluoride, metals, pesticides and aesthetic parameters from the plant outlets, reservoirs and reticulation sites on the schedule approved by the health regulator, analysed by an accredited laboratory and recorded in the Water Quality Sampling Register.

6.Incident and emergency response

Water quality incidents are managed under the Water Quality Incident Response Procedure with the Control Centre and Water Quality Manager as incident controller. The plan is linked to the business emergency management plan for flood, bushfire, power failure and chemical supply failure.

7.Improvement program

Improvements scheduled for 2026 to 2027 include a second online turbidimeter on filter 3, ultraviolet disinfection design for the bore field, replacement of the raw water storage algae monitoring buoy, backflow device audits on all food processing connections and confined space rescue training for reservoir entry.

8.Review and audit

This plan is reviewed annually by the drinking water quality committee, after every level 2 or level 3 incident and before each regulatory audit. Audit findings are recorded with actions, owners and dates.