Effect of domestic effluents on groundwater quality: A case study

In order to evaluate the effects of seeping septic effluents on the quality of groundwater in a watershed, a number of contaminants such as nitrate, phosphorus, chloride, lead, copper, iron, and manganese, were studied. To determine the extent of contamination, a network of observation wells was established in the drainage area of the septic systems. Groundwater samples from the observation wells were collected in the spring, summer and fall of 1981, 1982 and 1983. The samples were extracted for the determination of various contaminants by standard methods. The results indicated that nitrate, phosphorus, and chloride were coming from septic systems and were moving into groundwater. Nitrate and chloride levels were less than the maximum allowable limits in drinking water, whereas phosphorus was above the limits in 41% of the wells. According to the data obtained, the concentrations of iron and manganese were above the recommended levels in 27 and 50% of the wells, respectively. The concentrations of lead and copper were below the allowable maximum levels in drinking water. The results indicate contamination of groundwater in the study area with phosphorus, which could be attributed to domestic use of detergents, and iron and manganese, which could be attributed to corrosion of household pipes.