Improving safe sanitation practices using groundwater transport modelling and water quality monitoring data

Abstract

In many developing countries, poorly constructed pit latrines are the primary source of groundwater contamination. Approaches are needed to identify site-specific separation distances between domestic wells and pit latrines. In this study, tracer transport simulations are combined with water quality monitoring data to identify separation distances in peri-urban Dar es Salaam. Bivariate correlation and linear regression models were used to find the relationships between (1) simulated tracer and distances from the wells to the nearest pit latrines (2) simulated tracer and observed contaminants (nitrate, E. coli, and total dissolved solids). The results showed a strong correlation between tracer with nitrate and E. coli, with Pearson coefficient (r) values of 0.80 and 0.79, but a weak correlation with TDS (r=0.23). A strong correlation between tracer and distance for shallow and deep wells (r=−0.96, −0.76) was found. Based on the soil type and aquifer properties in the area, wells must be placed at least 34 m from a pit latrine to minimize contamination. With recent advances in sensor technologies and the availability of low-cost sensors, linking simulated tracer with observed contaminant levels may provide an alternative first approach to quickly assess human health risks associated with groundwater contamination.

Microbial Contamination of Groundwater Self‐Supply in Urban Indonesia: Assessment of Sanitary and Socio‐Economic Risk Factors

“…Results from this study should be interpreted with caution since some data on sanitation systems such as setback distance and sub‐surface design attributes were self‐reported by households or estimated by enumerators. Further studies into sanitation‐groundwater interactions in urban Indonesia might also consider groundwater flow and transport modeling (Ngasala et al., 2021), monitoring networks with new installed sanitation systems and piezometers (Ravenscroft et al., 2017), and spatial GIS databases (Martínez‐Santos et al., 2017).…”

A Review on In-Situ Denitrification Technology for Consideration in Jaffna Peninsula Aquifer Remediation

“…Activities leading to nitrate leaching are prohibited within the protection zones (UK Environment Agency 2009). For the second problem (pit latrines), a 34 m distance should be maintained between septic tanks and groundwater sources (Ngasala et al 2021).…”