Abstract: Water samples were collected along the tributaries of a drinking water source catchment for analysis in line with the procedure for risk assessment of the USEPA, and environment health risk of phthalic acid esters (PAEs) was assessed by taking into account the parameters of the region. Results show that (1) all the samples were found to have PAEs like pollutants, including Di (2-ethylhexyl) phthalate (DOP), diethyl phthalate (DEP), di-n-butyl phtalate (DBP), among which DOP was higher than the other two, displaying an order of DOP > DEP > DBP. (2) The concentrations of DOP, DEP and DBP in the water catchment were all higher than their respective ones in other drinking water source catchments in the region and could also be sorted into the moderate or upper level of contamination in similar areas in the country and others. DOP was designated the primarily controlled contaminant of the water source catchment.(3) In areas less affected by anthrogenic disturbance, environmental health risk of pollutants in rivers was low, while in areas densely populated and concentrated with industry, the risk was high. Along a river, the risk was low in the upper reaches, high in the middle reaches and low again in the lower reaches or the reservoirs.Therefore, it can be concluded that the environment health risk of PAEs like contaminants in headwater catchment has not yet exceeded the criteria of USEPA, but among similar regions the world over, this region is moderate or high in concentration of PAEs like contaminants and does have some potential health risks. It is, therefore, essential to track potential source of PAEs in the region and take corresponding countermeasures to control the sources in environmental risk management of the region.