An assessment of quality of water from boreholes in Bindura District, Zimbabwe

Abstract

This study assessed the water quality of 144 boreholes in Bindura District in Mashonaland Province of Zimbabwe as part of a borehole rehabilitation project implemented by a local NGO. In previous studies it has been observed that some boreholes are not used for domestic purposes because of consumer perceived poor water quality. Consequently, communities have resorted to unsafe alternative water sources thus creating health risks. The study was carried out in June 2005. The objectives of the study were to assess the levels of parameters associated with the aesthetics of the water and to compare them with guideline values for drinking water. The study also investigated the relationship between some of the measured water quality and the consumer perceived water quality. Measured water quality parameters included pH, temperature, electrical conductivity (EC), turbidity, calcium (Ca), magnesium (Mg) and iron (Fe). All parameters were measured in the field except Ca, Mg and Fe, which were measured in a laboratory using a spectrophotometer. Consumer perceptions on water quality were investigated through interviews with the consumer community. Turbidity was found to be 0.75–428(20.8 ± 59.2; n = 144) NTU, pH 5.7–9.3 (6.88 ± 0.46; n = 144), temperature 18–26.8 (22.6 ± 2.1; n = 144) °C. EC 26–546 (199 ± 116; n = 144) μS/cm, Ca 6–71.6 (26.9 ± 14.1; n = 81) mg/l, Mg 1.2–49.6 (12.3 ± 10.0; n = 81) mg/l and Fe 0.08–9.60 (0.56 ± 1.15; n = 81) mg/l. Some 23% of the samples had pH outside the recommended range of 6.5–8.5, whilst 59% of the samples had turbidity values exceeding the 5NTU WHO limit. For EC, all samples had values less than the WHO derived limit of 1380 μS/cm. All Ca and magnesium values were within the common and recommended levels of 100 mg/l and 70 mg/l respectively. Iron had values greater than the WHO and SAZ limit of 0.3 mg/l in 36% of the samples. Water quality was deemed satisfactory for taste and soap consumption by 95% and 72% of the respondents respectively. Satisfaction was higher for drinking compared to soap consumption meaning that generally hard waters may still be acceptable for drinking purposes. The water quality met the stipulated standard or guideline value from a minimum of 41% (turbidity) to a maximum of 100% (EC, Ca and Mg). There was no correlation between taste and conductivity as some 5% of the respondents suggested the water was unsatisfactory although all EC values were far below the maximum limit. Again there was no correlation between iron and taste as iron had 36% of the samples above the threshold of 0.3 mg/l whilst objectionable taste perception was only in 5% of the cases. It is recommended that priority in future projects should be given to repairs of boreholes whose water quality is acceptable according to consumer perceptions obtained at project planning stage. Low cost household treatment aimed at improving quality should be investigated.