Groundwater contamination occurs when hazardous substances dissolve in the water that has soaked into the soil. It can affect the health of animals and humans when they drink or bathe in contaminated groundwater or when they eat organisms that have been affected by groundwater contamination (see the animation below) .
Groundwater can become contaminated by:
- rain water or surface water mixing with contaminated soil while seeping into the ground, carrying the contamination from the soil to the groundwater
- liquid hazardous substances soaking through the soil or rock into the groundwater
- contact with long-term sources of ground water contamination that are pooled within the soil or bedrock, contaminating other groundwater sources as they flow through the soil or rock that contacts them
Contaminated groundwater can only hurt animals, plants, or humans if it is removed from the ground by:
- manmade process - in many parts of the world, groundwater is pumped out of the ground so it can be used as a source of water for drinking, bathing, other household uses, agriculture, and industry
- natural processes - groundwater can reach the surface through natural pathways such as springs.