Groundwater contamination is a situation which arises when groundwater becomes polluted by substances of human origin. Since groundwater is generally regarded as safe to drink, groundwater contamination can become a serious issue, as people may drink the water, not realizing that it has become dangerous to consume. There are a number of potential sources of groundwater contamination, making regular testing of groundwater supplies critical to ensure that the water is still clean.
Groundwater is water which is stored underground. It forms when water from lakes, rivers, streams, snow melt, and rain trickles underground, becoming trapped there. When a deposit of groundwater is large enough to sustain human consumption, it becomes known as an aquifer. There are two primary types of aquifers: confined and unconfined. In a confined aquifer, the groundwater is surrounded by an envelope of impermeable rock, while an unconfined aquifer is surrounded by permeable materials, putting it at risk of contamination.
Chemicals, road salt, bacteria, viruses, medications, fertilizer, and fuel can all cause groundwater contamination. Some common sources of contamination include: leaking storage tanks, the use of chemicals in farms, landfills, poorly controlled hazardous waste sites, and septic systems. Groundwater contamination can also occur when factories dump materials into surrounding waterways, and when polluted runoff from storm drains reaches the aquifer.
Many nations have strict laws concerning the release of pollutants, to prevent groundwater contamination and other environmental problems associated with pollution. However, regular inspection of the thousands of potential sources of pollution is simply not possible, and nations rely on individual citizens and companies to exercise caution when it comes to handling and disposing of materials which could cause groundwater contamination.
Once the aquifer is contaminated, it is very difficult to clean up. Sometimes, the water can be cleaned with filtration systems, but in other cases, it may be rendered useless. Since much of the world's supply of drinking water comes from groundwater, this makes groundwater contamination a serious problem. Especially in a community which cannot afford to ship in clean sources of water, people may be forced to drink the contaminated groundwater, because there is no alternative.
The issue of groundwater contamination is one reason why artesian wells are so popular. Artesian wells are wells which have been sunk into confined aquifers, accessing water which is locked safely inside a layer of impermeable rock. The water from such wells tends to be pure, and sometimes very flavorful, thanks to the dissolved minerals from the surrounding rock.