At the heart of the Australian Drinking Water GuidelinesFramework are critical control points (CCPs). A CCP is an activity, procedure or process that is critical to control a water quality hazard. CCPs must be monitored regularly, ideally continuously, to ensure the effectiveness of barriers. Properly operated CCPs help ensure safe drinking water.
The most important CCPs are filtration (where present), disinfection and maintaining reservoir integrity. Water utilities may establish other CCPs, including fluoridation and selective abstraction of raw water.
A water utility’s drinking water management system should define each CCP including the appropriate target and critical limit. Values need to be set for each CCP:
A water utility must consult with the local Public Health Unit and the Department of Industry Water before changing a CCP, particularly the critical limit. Proposed plant upgrade or modification may require assessment and approval by Department of Industry (DoI) Water. Values from the Australian Drinking Water Guidelines that have been used to set critical limits are shown in the table and agreed between NSW Health and DoI Water.
Standard operating procedures (SOPs) for maintaining CCPs must be easily accessible to operational staff and displayed at the CCP location or control room. SOPs provide guidance on maintaining operation in the target range, responding to adjustment limit and critical limit exceptions, and dealing with changes in raw water quality. Water utilities must respond promptly to adverse signals including operational monitoring results, alarms and weather warnings.
A CCP exception occurs when monitoring shows operation beyond the critical limits. This indicates that the safety of the water may be compromised.
Water utilities must immediately notify their local Public Health Unit of any incident affecting drinking water safety, including CCP exceptions, reservoir contamination and test results indicating possible contamination.
Some drinking water supplies are currently unable to meet the CCP values in the Australian Drinking Water Guidelines. The performance of some water supplies could be improved through optimisation of processes and operational controls. Department of Industry Water and NSW Health can assist with assessing risks and control options, optimising treatment processes, and establishing appropriate targets, adjustment limits and critical limits.
To control health risks, implementation of drinking water management systems should include:
Critical limits and target criteria from the Australian Drinking Water Guidelines should be used to specify performance of new water supply systems and for major upgrades of existing plants.