Abstract:
Ground water is one of the most important sources of drinking water in rural areas of Elfeta
district, Oromia, Ethiopia; hence, it is important to assess and evaluate the quality of these water
sources. The objective of this study was to investigate the levels of some selected
physicochemical parameters and heavy metals, and assess associated health risks in protected
dug well water sources of Elfeta district of Oromia, Ethiopia. For this purpose, from seven
different protected dug well in seven rural villages, water samples were collected using
composite sampling technique during the wet season to serve as the subject of the study. Level of
nine heavy metals and twelve physicochemical in water were determined using Flame Atomic
Absorption Spectroscopy and standard analytical methods respectively. The observed mean
values of the physicochemical analysis were in the range of 6.4 ± 0.2- 6.9 ± 0.03, 14.5 ± 0.2 -
16.9 ± 0.3 °C, 59 ± 4 - 715 ± 4.1 μS/cm, 0.013 ± 0.001 - 0.03 ± 0.02 mg/l, 7.3 ± 0.5 - 33 ± 3 mg/l,
7.1 ± 0.01 -12.9 ± 0.02 mg/l, 38. ± 2.4 - 435 ± 10.8 mg/l, 38 ± 3 - 62 ± 4 mg/l, 31 ± 0.9 - 77 ± 1.9
mg/l, 2.15 ± 0.3 - 8.8 ± 0.8 mg/l, 0.01±0.002- 0.06 ± 0.002 mg/l and 0.7 ± 0.1 - 4.3 ± 0.3 NTU
for pH, temperature, conductivity, nitrite, nitrate, sulphate, total dissolved solid, total hardness,
total alkalinity, chloride, phosphate and turbidity, respectively. The concentrations of heavy
metals (mg/l) in the water samples were found within the range of 0.07± 0.003 - 0.22 ± 0.008,
0.0078± 0.0004 - 0.0091 ± 0.0001 and 0.04 ± 0.001 - 0.13 ± 0.004 for Fe, Cd, and Zn,
respectively. The heavy metals including Pb, Co, Cu, Ni, Cr and Mn were not detected. The
concentration levels of all the studied heavy metals, except Cd, were below the permitted limits
for drinking water established by the WHO and Ethiopian Standard Agency (ESA). The results of
the non-carcinogenic human health risk assessment for individual and mixture of the studied
heavy metals indicated that the examined heavy metals were can pose negligible human health
risk (i.e., total hazard quotients (i.e., HQ < 1 and HI < 1). However, the incremental lifetime
cancer (ILCR) risk assessment result showed that the observed concentration level of Cd can
cause severe cancer risk (ILCR > 1x10-4) to the consumers
