3.4.2 Operational monitoring

Summary of actions

• Develop monitoring protocols for operational performance of the water supply system, including the selection of operational parameters and criteria, and the routine analysis of results.

• Document monitoring protocols into an operational monitoring plan.

Operational monitoring includes the planned sequence of measurements and observations to assess and confirm the performance of preventive measures. Observations could include activities such as regular inspections of the catchment (e.g. for integrity of fences), plant equipment, wellhead protection areas and bore construction. Measurements are of operational parameters that will indicate whether processes are functioning effectively.

The general intent of operational monitoring is different from that of drinking water quality monitoring (see Section 3.5.1). Operational monitoring is used to confirm that preventive measures implemented to control hazards are functioning properly and effectively. Data from operational monitoring can be used as triggers for immediate short-term corrective actions to improve drinking water quality.

Key elements of operational monitoring include:

• development of operational monitoring plans from catchment to consumer, detailing strategies and procedures;

• identification of the parameters and criteria to be used to measure operational effectiveness and, where necessary, trigger immediate short-term corrective actions;

• ongoing review and interpretation of results to confirm operational performance.

Further guidance on operational monitoring is provided in Chapter 9.

Operational parameters

Operational parameters should be selected that reflect the effectiveness of each process or activity, and provide an immediate indication of performance. Typically, operational monitoring should focus on parameters that can be readily measured and enable a rapid response. To fulfil these requirements, surrogates are often used as operational parameters rather than direct measurement of the hazards themselves. For example, turbidity may be used as a surrogate for Cryptosporidium and Giardia. More detail on surrogates is provided in Chapter 9.

Operational parameters should be monitored with sufficient frequency to reveal any failures in good time. Online and continuous monitoring should be used wherever possible, particularly at critical control points (see below). Examples of parameters that can be used for operational monitoring are provided in Table 9.1, Chapter 9.

Target criteria and critical limits

Once operational parameters are identified, target criteria (performance goals) should be established for each preventive measure. These criteria can be quantitative (numerical) or qualitative (descriptive). Any deviation of performance from established targets should be regarded as a trend towards loss of control of the process, and appropriate action should be taken to resolve potential problems.

For preventive measures identified as critical control points for the water supply system, critical limits must also be defined and validated. A critical limit is a prescribed tolerance that distinguishes acceptable from unacceptable performance at a critical control point. When a critical control point is operating within the prescribed limits, performance in terms of hazard removal is regarded as being acceptable. However, exceedance of or deviation from a critical limit represents loss of control of a process and indicates an unacceptable health risk. Corrective actions should immediately be instituted to resume control of the process, and the relevant health authority or drinking water regulator should be notified.

Setting target criteria that are more stringent than critical limits at critical control points will enable corrective actions to be instituted before an unacceptable health risk occurs. Exceedance of a target criterion at a critical control point would generally not require that the relevant health authority or drinking water regulator be notified, providing corrective action successfully prevented deviation from a critical limit.

Chapter 9 provides more explanation of target criteria, critical limits and monitoring at critical control points.

Analysis of results

Results must be reviewed frequently to confirm that records are complete and accurate, and that there are no deviations from critical limits or target criteria. Where results indicate that control has been lost, appropriate corrective actions and process adjustments should be instituted to maintain quality. Those responsible for interpreting and recording operational results should clearly understand how the results should be assessed.

A system should be established for regular reporting of operational monitoring results to relevant staff and departments. Methods such as graphs or trend charts can be used to facilitate the interpretation of operational monitoring results. More guidance on short-term evaluation of results for assessing drinking water safety is provided in Section 10.2.