- Borehole water contained higher fluoride concentration than water from springs.
- Some water sources (14% of samples) contained fluoride levels higher than 1.5 mg/L, the WHO guideline value for drinking water.
- High fluoride levels correspond to high TDS values at near-neutral pH.
- A modified Galagan equation was used to calculate the optimum fluoride in water for Sukulu Hills, and was found to be 0.4 mg/L. All water samples contained fluoride >0.4 mg/L.
This study was carried out to assess fluoride (F?) concentration and to determine its upper permissible limit in groundwater from Sukulu Hills, a phosphate mining area in Tororo District, Uganda, where groundwater is the main source of drinking water. Water samples were collected from boreholes and protected springs within a three-kilometer radius from the foot of the Hills. The physico-chemical parameters and F? concentration were analysed using potentiometric methods. The water samples collected had a pH range of 6.0–7.2, electrical conductivity of 148–750 µS/cm, and TDS values of 75–378 mg/L; and these parameters were within the WHO normal range for drinking water. F– concentration in groundwater from boreholes ranged from 0.4 to 3 mg/L, whereas in springs it was from 0.2–2.4 mg/L. High F– levels corresponded with higher TDS values at near-neutral pH. The WHO and Uganda National Bureau of Standards (UNBS) guideline value of 1.5 mg/L F– was exceeded by groundwater from spring S3 and boreholes B3 and B7 (14% of samples) in the study. Given the five-year average weather conditions of Tororo, a modified Galagan equation was applied to calculate the recommended F? level in drinking water for the area, and was found to be 0.4 mg/L. All water sources studied contained average F? levels higher than 0.4 mg/L. These findings imply a possible risk to the local population which depends on this water being exposed to dangers of high F– intake.