Ecological and geological materials for drinking water treatment in Tanzania: A review of sustainable local resources

Tanzania continues to face persistent drinking water contamination, particularly from geogenic fluoride in the Rift Valley regions such as Arusha, Manyara, and Singida and from heavy metals and microbial pollution in other affected areas. Heavy metals from mining, volcanic soils, and anthropogenic sources further compromise water quality, elevating risks of dental and skeletal fluorosis and heavy metal toxicity. This review synthesizes evidence on the use of locally available ecological and geological materials, such as Moringa oleifera seeds, bone char, volcanic rocks, bentonite, and pumice, as sustainable alternatives for drinking water treatment in Tanzania. A search of Scopus, Web of Science, and AJOL identified 120 peer‑reviewed studies published between 1990 and 2025. By discussing their treatment performance, availability, and practical limitations, the paper identifies pathways for decentralized, low-cost, and culturally acceptable water treatment solutions. Laboratory findings highlight the strong potential of bone char to achieve fluoride adsorption capacities of 5–10 mg/g, moringa seeds remove > 99% turbidity through coagulation, and pumice demonstrates microbial filtration capacity. Indigenous ecological and geological materials thus offer promising pathways toward safe drinking water in Tanzania. However, community-scale adoption remains limited by supply constraints, production quality, and sociocultural acceptance. Community‑led scale‑ups, aligned with national water policy, could enable decentralized, low‑cost treatment solutions. Long‑term sustainability should be advanced through pilot testing of hybrid systems and supportive policy frameworks. The review highlights the need for pilot-scale validation, policy support, and locally adapted implementation strategies to advance safe and sustainable drinking water treatment in Tanzania.