Centralized or Onsite Testing? Examining the Costs of Water Quality Monitoring in Rural Africa

John T. Trimmer, Caroline Delaire, Katherine Marshall, Ranjiv Khush, and Rachel Peletz (2024) Centralized or Onsite Testing? Examining the Costs of Water Quality Monitoring in Rural Africa. Environmental Science & Technology. DOI: 10.1021/acs.est.4c01916

Abstract

Rural water systems in Africa have room to improve water quality monitoring. However, the most cost-effective approach for microbial water testing remains uncertain. This study compared the cost per E. coli test (membrane filtration) of four approaches representing different levels of centralization: (i) one centralized laboratory serving all water systems, (ii) a mobile laboratory serving all systems, (iii) multiple semi-centralized laboratories serving clusters of systems, and (iv) decentralized analysis at each system.

Four approaches to water quality monitoring considered in this study. Each diagram provides an illustration of what sample collection might look like on a given day, as shown by the arrows and changing locations of the mobile laboratory.

We employed Monte Carlo analyses to model the costs of these approaches in three real-world contexts in Ghana and Uganda and in hypothetical simulations capturing various conditions across rural Africa.

Centralized testing was the lowest cost in two real-world settings and the widest variety of simulations, especially those with water systems close to a central laboratory (<36 km). Semi-centralized testing was the lowest cost in one real-world setting and in simulations with clustered water systems and intermediate sampling frequencies (1–2 monthly samples per system). The mobile lab was the lowest cost in the fewest simulations, requiring few systems and infrequent sampling. Decentralized testing was cost-effective for remote systems and frequent sampling, but only if sampling did not require a dedicated vehicle. Alternative low-cost testing methods could make decentralized testing more competitive.

In collaboration with USAID and Conrad N. Hilton Foundation.