Anthropogenic pollution such as urban and industrial wastewater is the major factor increasing groundwater contamination in most cities. Effluent discharges on in-stream or near-stream surface waters can potentially transport not only water but wastewater-contaminants to shallow unconfined aquifer systems. In addition, on-site septic system discharges containing nutrients and organic compounds also represent a high threat to groundwater affecting its quality and its availability for drinking.
In some countries, wastewater is used for agricultural irrigation and in arid areas as groundwater recharge. The use of wastewater for irrigation could provide economic means and may reduce the use of fertilisers. However, wastewater often contains a high concentration of minerals, heavy metals and microorganisms that could potentially be transported to the aquifer.
The use of treated wastewater for groundwater recharge appears to be an alternative to address water demand as it is considered a resource that is globally steadily increasing.