This study examines the case of Ekpoma community, Edo State, Nigeria, where roof-harvested rainwater is the primary source of water for drinking and domestic purposes. Eight potentially toxic elements (PTEs) namely aluminum, chromium, copper, iron, manganese, nickel, lead, and zinc, were detected in rainwater samples collected and analyzed from 54 sampling locations across the community. The elemental concentrations were quantified using atomic absorption spectrophotometry and compared using the regulatory standards of the World Health Organization, United States Environmental Protection Agency, and Nigerian Drinking Water Quality Standards. The PTEs detected in the rainwater samples can be attributed to the nature of the materials used in the roof catchment systems, storage tank conditions, anthropogenic effects from industrial and agricultural processes, and fossil fuel emissions. However, only 20% of the evaluated samples contained PTE concentrations below the allowable regulatory limits. Spatio-temporal health risk analysis conducted using HERisk software showed that children in the development phase (1–18 years) are most vulnerable to health risks in the community. After age 18, the risk increased by approximately 10% and remained constant until old age. In addition, the evaluation of the studied sites showed that 33% of the evaluated sites had negligible carcinogenic risks, while the other 61% were sites with low carcinogenic risks to residents.

  • The study examines the water quality and human health risk from drinking and using roof-harvested rainwater in Ekpoma community.

  • Eight chemical species were detected and analyzed.

  • Only 20% of the samples tested contained PTE concentrations within allowable limits.

  • Samples from the studied sites presented carcinogenic risks (61%) for residents.

  • Water ingestion route provided 98% risks for all resident

Graphical Abstract

Graphical Abstract
Graphical Abstract
This content is only available as a PDF.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (

Supplementary data