Assessment of Water Quality of Earth Dams in Chepalungu Sub-county, Bomet County, Kenya

Abstract

An assessment of water quality from six selected earth dams in Chepalungu Sub-County, Bomet County was carried out by determining the levels of pH, TDS, TSS, nitrate, ammonia, fluoride, phosphorus, copper, lead, zinc, cadmium and chromium. The objective of the study was to determine water quality from the six selected earth dams and compare with WHO (2011) drinking water guidelines. These earth dams are the alternative source of household water since large population in Chepalungu Sub-County are unable to get access to chlorinated drinking water supply. Three water sampling points were identified in each of the six earth dams. The total number of sampling points were 18. Samples collection was done in July, 2016 (dry) and April, 2017 (wet) seasons. Total of 36 earth dam water samples were collected in duplicate. 6 soil samples in duplicate, 2 fertilizers samples in duplicate and 2 rain water samples in duplicate were also collected. Metals were analyzed using Atomic Absorption Spectrophotometer. Nitrate, ammonia and phosphate were analyzed using UV/VIS spectrophotometer. pH and fluoride were analyzed using ion selective electrode meters. TDS and TSS were analyzed using gravimetric method. From the study, pH level and total suspended solids were within the recommended range by WHO (2011) drinking water guideline. Total suspended solids had range of between 8.91±0.64 mg/L and 175.9 ±4.91 mg/L which was higher than the allowable level of 30 mg/L. Nitrate ranged between 2.71±0.03 mg/L and 11.50 ±0.017 mg/L which was lower than maximum recommended level by WHO (2011). Copper ranged between <0.003 mg/L and 0.89±0.031 mg/L which was below maximum recommended level by WHO (2011). Zinc ranged from 0.07±0.01 mg/L to 4.92±0.040 mg/L and was higher than the maximum recommended level by WHO (2011). Chromium was detected during dry season in two earth dams only Cheboloigo and Kapewot with concentration of 0.46±0.055 mg/L and 1.98±0.053 mg/L respectively. Fluoride was higher than the maximum recommended level of 1.5 mg/L drinking water guideline except for Kapewot (1.25±0.031 mg/L) and Kaposur (1.42±0.02 mg/L) earth dams during dry season. The range of fluoride was between 1.25±0.031 mg/L and 5.33±0.05 mg/L. The level of the selected parameters in rain water were within the recommended levels. From the study high fluoride levels in water may have been from soils leaching in the area, soil from this area had high concentration of fluoride with a range of between 125±1.00 mg/L and 683±3.06 mg/L. The study reveals that water from these earth dams should be treated to avoid long term health effect of high concentration of fluoride.