What is the difference between point-source and nonpoint-source water pollution?
Point sources come from discrete pipes flowing into a river for example. Non-point are more diffuse sources that don't come from one single pipe or outlet.
Explanation:
Point sources are for example, water discharging from an industrial plant of some kind or a waste water treatment plant. Non-point sources include run-off from agricultural lands that may wash fertilizer or other chemicals into lakes or rivers this may occur over thousands of square kilometres.
From an environmental perspectives, it is usually easier to deal with point source emitters than non-point.