How we assess water safety: A critical review of sanitary inspection and water quality analysis

Sanitary inspection is used in low-, medium- and high-income settings to assess the risk of microbial contamination at water sources. However, the relationship between sanitary inspection and water quality is not well understood. We conducted a critical literature review and synthesized the findings of 25 studies comparing the results of sanitary inspection and microbial water quality analysis. Most studies used sub-standard sanitary inspection and water quality analysis methods, and applied simplistic comparisons that do not characterize the complexity of the relationship. Sanitary risk score was used to represent sanitary inspection results in 21 (84%) studies; of which 12 (57%) found a significant association between score and microbial water quality and nine (43%) did not. Participatory sanitary inspection (12%) and reporting results back to communities (24%) were uncommon. Most studies relied on laboratory-based water quality analysis as an independently sufficient measure of safety, but reported inadequate quality control (52%) and/or sub-standard sample processing methods (66%).

We found that sanitary inspections could contribute to improving water safety through four mechanisms: guiding remedial action at individual water sources, allowing operators and external support programs to prioritize repairs, identifying programmatic issues, and contributing to research. The purpose of the sanitary inspection should be considered when planning sanitary inspection execution, data analysis, and reporting to ensure appropriate methods are employed and results are fit for purpose. Further exploration should recognize that sanitary risk factors represent sources of contamination, pathways for contaminants to enter water supplies, and breakdowns in barriers to contamination. These different sanitary risk factor types have different and inter-dependent effects on water quality.