Groundwater is water under the earth’s surface held in soil pores and in cracks in the rocks.

Pollution of groundwater is a major problem that is affecting everyone. Little is being done by people in authority to manage water pollution.

Where does groundwater come from?

Ground water
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After precipitation (rain, snow, hail, sleet), the water seeps into the ground. Some water is used up by plants while some seep deep until it reaches a layer of rocks where it cannot seep further. The water then fills the cracks and empty spaces beneath, forming what is referred to as groundwater.

Why is groundwater significant?

  • According to the US Geological Survey (USGS), 50% of US residents use groundwater for drinking and house chores.
  • The biggest use of groundwater is crop irrigation.


Polluting groundwater has direct effects on humans, animals, crops, and the ecosystem.

So, how is groundwater polluted?

Groundwater is polluted in many ways. The type of pollution can be natural or caused by humans.

Here are some of the leading causes of groundwater pollution

Natural pollution

Natural occurring substances like arsenic, fluorides, chlorides, magnesium, iron, sulfates, and radionuclides pollute water. These natural substances dissolve in groundwater, which then affects humans, plants, and animals. Decaying organic matter also pollute groundwater.

Septic tanks

septic tank

Septic tanks hold toilet waste, detergents, chemicals, bacteria, and viruses. Since most are built in the ground, they often leak, causing pollution of groundwater.

Hazardous waste

Most hazardous wastes need proper disposal by experts. Things like garden chemicals, medicine, batteries, oil, and others should not be emptied in water sources. Often, these pollutants are disposed of in water sources that affect groundwater.

Landfill contamination


Some chemical containers are disposed of in landfill sites. If the chemicals are hazardous, they are washed by rain-water, which affects groundwater.

Herbicides, pesticides, and fertilizers

Farm chemicals often have toxic effects on water sources. A study conducted by EPA between 1985 and 1992 found out that over 3.6% of wells have nitrates concentrations higher than the recommended levels. The study also found that pesticide presence in 14.6% of wells.

Here are the full statistics from the survey. Nitrates occur naturally in the ground, but their levels are increased significantly by fertilizers.



During mining, some harmful chemicals like cyanide are used. Cyanide is used to separate gold from ore, and sulphuric acid is used in iron mining. The leakage of mining chemicals affects groundwater. It is a similar case in the Santa Cruz aquifer, which is filled with leached chemicals. 

What are the effects of groundwater pollution?

Clean-up operation costs are huge. Some level of water pollution is irreversible, which may result in abandonment of the only watercourse available for some communities.

Contaminated water impacts estuaries and ecosystems. Contaminates like nitrogen cause irreversible damages in the habitats and affect plant life. Nitrate pollution causes enormous algae bloom, which blocks sunlight and affects oxygen levels in the water. The lack of oxygen suffocates fish and other water animals.

What is being done about groundwater pollution?

 The government is enforcing some policies to protect water sources. While some laws look hell-bent on undoing them, they are working quite well.


If you suspect your water source is contaminated, you can use the whole home or reverse osmosis water filter to purify your water.