Assessment of nitrate concentration in drinking water sources in rural areas of Ethiopia Adugnaw Tadesse 1 , Mamaru A. Moges 1 , Debebe Lijalem 1 , Dessalegn C. Dagnew 1 , Tewoderos Taffese 1 , Mulugeta A. Belete 1 , Seifu A. Tilahun 1 , and Tammo S. Steenhuis 1,2* 1 School of Civil and Water Resources Engineering, Institute of Technology, Bahir Dar University, Ethiopia 2 Department of Biological and Environmental Engineering, Cornell University, Ithaca, USA Abstract—Access to drinking water in Ethiopia has improved over the past ten years. However how safe the water is, is not known since the quality is not monitored. There is a concern for nitrate contamination from the increasing levels of farmer applied fertilizers and the high cattle density. The objective of this study is to assess the nitrate level of drinking water sources. Fifty six randomly selected potable water systems were selected located in Farta, Estie and Andabet woredas of the south Gondar zone, northern Ethiopia. Approximately 85% of samples were collected from hand dug wells and the remaining 15% from developed springs. The results indicate that nitrate levels range between 0.1 mg/L and 16 mg/L. The average concentration in hand dug wells was 3.8 mg/L and in developed springs was 0.3 mg/L. Nitrate concentrations in potable water systems surrounded by agricultural fields were more than twice grazing and forest land. Topographically, average concentration of nitrate were1.4 mg/L in the upslope, 5 mg/L in the mid slope and 2.4 mg/L at the lower slope indicating that denitrification is occurring in the periodically saturated lower slope areas the nitrate levels that exceed the WHO standards of maximum contaminant limits for drinking water (10 mg/L No - 3 -N) were found in five percent of the sampled hand dug wells and none in the developed springs. Key words: Nitrate concentration, Water quality, rural water supply, Ethiopia I.INTRODUCTION Groundwater historically has been the preferred source for potable water because of its superior quality. However, Improper waste management, agricultural activties such as application of chemical fertilizers, poor sanitation, low level of hygiene in Ethiopia are threathening its quality [1]. Nitrate (NO 3 - ) is one of the several inorganic pollutants contributed by nitrogenous fertilizers, organic manures, human and animal wastes. Increasing the level of nitrate has degraded drinking water quality [2]. Nitrate is the most frequently introduced pollutant into the groundwater system [3]. High levels of nitrates in groundwater, originating mainly from agriculture activities, have been encountered in almost all regions of the world [4]. Drinking water contamination by nitrate is public health concern because nitrate can undergo endogenous reduction to nitrite and nitrosation of nitrites can form N-nitroso compounds which are potent carcinogens [5]. Risks associated with high level of nitrate in the drinking water on human health includes but is not limited to the dysfunction of thyroid gland, gastric cancer, decrease the capacity of blood to transport oxygen known as metahemoglobinemia for infants below six months old [6, 7] and also poses health problems for pregnant women [8]. In addition to human health effects, excessive nitrates in groundwater can cause health problems in ruminate animals and environments [9, 10]; [11-15]. Nitrate levels in the groundwater of the world have been annually increasing from 1-3 mg/L [16] and several studies in different parts of the world showed that groundwater contamination with nitrate is a serious problem [3, 17-19]. A significant portion of these locations are agricultural areas where large amounts of nitrogen used to fertilize crops and intensification of agriculture [9]; [20]; [21]; [22]; [23]. Other greater threats to the groundwater quality are high density of cattle [22]; [24]. A study in Europe showed that nitrate concentration of groundwater is increasing due to intensively fertilized grazing land [24]. Studies conducted in European Economic Community countries showed different results. For example, in Germany the nitrate level in some areas is above 5.6 mg/L in groundwater; significant portion of areas are unprotected aquifers and areas with intensive agriculture. In France, in 1981 around 2% of the total population was supplied with water that had a nitrate content exceeding the WHO limit. In Belgium; in the southern parts of Brussels, intensive agriculture together with cattle and pig farm areas, nitrate level found in