3.4.3 Corrective action

Summary of actions

• Establish and document procedures for corrective action to control excursions in operational parameters.

• Establish rapid communication systems to deal with unexpected events.

Procedures should be developed for immediate corrective action to re-establish process control following failure to meet target criteria or critical limits. The procedures should include instructions on required adjustments, process control changes and additional monitoring. Responsibilities and authorities, including communication and notification requirements, should be clearly defined.

After implementing a corrective action, its effectiveness will need to be verified. This usually requires additional monitoring. Secondary impacts of the corrective action, and whether adjustments or action is needed further along in the supply system, should also be considered.

Examples of possible corrective actions include:

• selection of an alternative raw water source if available and able to meet the health-based targets;

• altering the plant flow rate (e.g. reducing loading);

• jar testing for coagulant control and optimisation;

• altering the mixing intensity;

• changing treatment chemicals;

• using auxiliary chemicals such as coagulant aids, flocculant aids, filtration aids;

• adjusting pH;

• varying chemical feed rates and feed points;

• adjusting filtration loading rate or operation;

• increasing disinfectant dose;

• secondary or booster disinfection;

• mains flushing, cleaning and localised disinfection.

Where possible, the underlying cause of the problem should be determined and measures implemented to prevent future occurrences. Analysis of the causes may identify possible solutions, such as modifying an operating procedure or improving training. Details of all incidents should be recorded and reported.

While advance planning is important, it will not always be possible to anticipate every type of event. Rapid communication systems should be established to deal with these events.

Incident and emergency responses should be prepared for times when normal corrective actions cannot re-establish operational performance quickly enough to prevent drinking water of unacceptable quality from reaching consumers.

Section 10.2 provides more discussion of corrective actions and incident and emergency responses.