Fluorosis has been prevalent in the great East African Rift Valley (EARV) since before this region was given a name. In the Tanganyika days, Germans reported elevated fluoride concentrations in natural waters. In the 1930s, the clear relationship between high fluoride level and mottling of teeth was established. Since then, the global research community has engaged in the battle to provide fluoride-free drinking water, and the battle is not yet won for low-income communities. An applicable concept for fluoride-free drinking water in the EARV was recently presented, using the Kilimanjaro as a rainwater harvesting park. The Kilimanjaro concept implies that rainwater is harvested, stored on the Kilimanjaro mountains, gravity-transported to the point of use, eventually blended with natural water and treated for distribution. This article provides a roadmap for the implementation of the Kilimanjaro concept in Tanzania. Specifically, the current paper addresses the following: (i) presents updated nationwide information on fluoride contaminated areas, (ii) discusses the quality and quantity of rainwater, and current rainwater harvesting practices in Tanzania, (iii) highlights how low-cost water filters based on Fe0/biochar can be integrating into rainwater harvesting (RWH) systems to provide clean drinking water, and (iv) discusses the need for strict regulation of RWH practices to optimize water collection and storage, while simplifying the water treatment chain, and recommends strict analytical monitoring of water quality and public education to sustain public health in the EARV. In summary, it is demonstrated that, by combining rainwater harvesting and low-cots water treatment methods, the Kilimanjaro concept has the potential to provide clean drinking water, and overcome fluorosis on a long-term basis. However, a detailed design process is required to determine: (i) institutional roles, and community contributions and participation, (ii) optimal location and sizing of conveyance and storage facilities to avoid excessive pumping costs, and (iii) project funding mechanisms, including prospects for government subsidy. By drawing attention to the Kilimanjaro concept, the article calls for African engineers and scientists to take the lead in translating this concept into reality for the benefit of public health, while simultaneously increasing their self-confidence to address other developmental challenges pervasive in Africa.

This study investigated the levels of Pb, Hg, Cr, Cd, and As in water and sediments from the tributaries of the Mara River, Tanzania. Pollution risk of water and sediments was investigated using seven indices and five metals. During the dry period, the highest concentration of Pb, Hg, Cr, Cd, and As in sediments was 17.45 ± 1.22, 0.01, 1.56 ± 0.5, 1.3 ± 0.09, and 30.81 ± 0.02 mg/kg, respectively. During the wet period, the highest concentration of Pb, Hg, Cr, Cd, and As in sediments was 4.37 ± 0.28, 0.012, 2.58 ± 0.57, 2.25 ± 0.35, and 53 ± 0.02 mg/kg, respectively. For surface water, the respective highest concentrations of Pb, Hg, Cr, Cd, and As were 0.76 ± 0.09, 0.04, 0.68 ± 0.09, 0.74 ± 0.1, and 0.47 ± 0.06 mg/L for the dry period. The wet period max concentrations for Pb, Hg, Cr, Cd, and As in surface water were 0.56, 0.03, 0.55 ± 0.03, 0.48 ± 0.03, and 0.4 ± 0.03 mg/L, respectively. Principal component analysis results indicated dominant loadings for Pb and As in sediments during the dry period. Comparison of sediment concentrations with sediment quality guidelines revealed that As and Cd were enriched. Correlation coefficient results indicated that As had a strong negative correlation with the rest of the elements in sediments during the dry period. In the wet period, As had a significant correlation with Cd (r = 0.92, p < 0.01) in sediments. The analysis of environmental risks indicated significant enrichment of sediments with As and Cd. It is important to put in place relevant control mechanisms targeting metals in the studied tributaries, with a focus on As and Cd.

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