235-12 Understanding the extent of Groundwater Pollution with Fluoride, Arsenic, and Other Geogenic Contaminants in Rwanda

Session: Advancing the Understanding and Management of Groundwater Pollution with Arsenic and Other Geogenic Contaminants Using Geospatial Tools, Machine Learning, and Data Science, Part I

Presenting Author:

Authors:

Abstract:

Groundwater remains the primary source of drinking water for most people in rural Rwanda. However, naturally occurring geogenic contaminants pose growing risks to public health, particularly in areas with complex volcanic and metamorphic geology. To address the lack of baseline data and systematic monitoring, a nationwide Rapid Assessment of Drinking Water Quality (RADWQ) was conducted in 2018 by the Rwanda Utilities Regulatory Authority (RURA), with support from UNICEF and in collaboration with the University of Rwanda. The study assessed 602 rural water supply sources and analysed water samples from 296 households that rely on these sources, with a focus on springs, boreholes, and piped systems. The findings revealed significant geochemical pollution challenges. Arsenic was identified as a high-priority contaminant. Six percent of water sources exceeded Rwanda’s maximum permissible level (10 μg/L), with the Northern Province showing the highest prevalence, affecting 21% of piped systems and 31% of springs. An estimated 420,000 people are at risk of arsenic-related illnesses, including skin disorders and cancers. Fluoride exceeded national guidelines (1.5 mg/L) in 10% of sources, primarily boreholes and springs in the Western Province. This places an estimated 760,000 people at risk of dental or skeletal fluorosis. Manganese levels were elevated in 57% of rural sources. While mainly an aesthetic concern, 7% exceeded the WHO health-based guideline (0.4 mg/L), affecting over 530,000 people, with potential neurotoxic effects in children. Iron exceeded the national limit (0.3 mg/L) in 15% of supplies, impacting taste and turbidity but posing no direct health threat. Mercury, particularly in the Eastern Province, surpassed the Rwandan standard (1 μg/L) in 26% of supplies. Though fewer samples (6%) exceeded the WHO guideline (6 μg/L), the affected population (~320,000) faces serious risks to kidney and nervous system health. These findings emphasize the urgent need for prioritizing safe source selection, pre-distribution testing, and targeted mitigation of arsenic and fluoride exposure. Expanding aquifer characterisation and delineation and deploying low-cost water treatment technologies or alternative water sources will be critical in safeguarding public health and achieving water safety targets in rural Rwanda.

Keywords: Groundwater, Geogenic Contaminants, Aquifer Characterisation, RADWQ

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11091

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.