# 3.11.1 Long-term evaluation of results Summary of actions * Collect and evaluate long-term data to assess performance and identify problems. * Document and report results. The systematic review of monitoring results over an extended period (typically the preceding 12 months or longer) is needed to: * assess overall performance against numerical guideline values, microbial health-based targets, regulatory requirements or agreed levels of service * identify emerging problems and trends * assist in determining priorities for improving drinking water quality. There will inevitably be occasions of non-conformance with operational criteria or numerical guideline values. Each event will need to be assessed and responses determined. Mechanisms for evaluation of results should be documented, with responsibilities, accountabilities and reporting requirements defined. Useful tools to enhance the interpretation of data sets include statistical evaluation of results and graphs or trend charts using a ‘control chart’ format (see Information Sheets 3.1 to 3.4). Evaluation of results should be reported internally to senior executive, and externally to consumers, stakeholders and regulatory authorities in accordance with established requirements (see Section 3.10.2). Providing assurance that data are reviewed regularly and that improvements are made in response to identified problems will contribute to consumer confidence. Section 10.3 provides further guidance on assessing long-term system performance. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-1/chapter-3/3.11-evaluation-and-audit-element-11/3.11.1-long-term-evaluation-of-results.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.