Field-testing solutions for drinking water quality monitoring in low- and middle-income regions and case studies from Latin American, African and Asian countries

This work highlights the need for a global approach to drinking water monitoring that involves facing several critical issues. Field tests that perform to very high standards of indicator microorganisms’ detection and confidence and, at the same time, being available in rural and isolated locations of low-income settings are urgently needed. Commercially available field-testing solutions for Escherichia coli determination based on hydrogen sulfide and defined substrate methods were critically reviewed, considering their capabilities and limitations, compliance against the UNICEF Target Product Profile (TPP), technology performance, availability, and cost. None of the available tests meets the standards set by the UNICEF TPP, the biggest limitation being the requirement of a power source. They need at least 18–24 h of incubation, hence they have not significantly decreased the amount of the time needed to complete an assay; and their applicability is generally limited by the sample volume. Additionally, there is still need for more accurate and standardised validation studies that open new opportunities for low-cost testing solutions in the field. On the other hand, traditional methods are the only ones legally authorised by national regulations in the case study locations, with a range of resources and technologies limitations. Despite the use of field kits is beginning to gain acceptance, its implementation in the field strongly relies on their availability and cost locally. Most field kits price exceed the maximum of 6 USD set by UNICEF, and they even cost significantly more when acquire from local distributors in developing countries.