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Potential Sources of Groundwater Contaminants 

Written by:
George Simms
Plumber & Contractor

Most of the US population, and nearly every household in rural areas, rely on groundwater for their water supply. However, groundwater is vulnerable to contamination from many human-made and natural pollutants. It can also be challenging and expensive to identify and resolve the problem.

If contaminated groundwater enters the public water supply, it can have severe consequences for consumers. Many pollutants may not be apparent when running your faucet, increasing the chances of drinking unsafe water. Polluted groundwater can also harm wildlife and could be hazardous for crop irrigation and gardens.

Knowing the potential sources of groundwater contamination helps keep the public water supply hygienic and safe.

Natural Groundwater Contamination Sources

Groundwater is present almost everywhere, filling the spaces between soil particles and fractured rock beneath the earth's surface. The water table can rise following rain or snow or lower in the drier months. Because it is part of nature, groundwater comes into contact with many naturally-occurring substances that can cause contamination. 

Different types of rocks and soils contain iron, arsenic, radionuclides, and other substances that can dissolve in groundwater. There may be decayed organic matter that presents as tiny particles in the liquid. While some pollutants can be harmful to health, many foreign bodies are safe for consumption in low concentrations. 

If the concentrations of potentially harmful matter reach unacceptable levels, public water providers exclude that source from drinking water supplies.

1. Septic Systems

Approximately 25% of the US population uses a septic system to dispose of their human waste. If a septic tank does not have robust construction, is in the wrong location, or is subject to excessive wear-and-tear, it can leak bacteria, viruses, chemicals, and other dangerous substances into the surrounding soil.

The majority of state and local authorities enforce strict regulations concerning the distance between separate septic tanks to reduce the risk of severe contamination in a specific area.

2. Sewers and Pipelines

Sewers carry waste away for disposal, and the pipes need to withstand heavy-duty use. Other pipelines in industrial use often transport corrosive chemicals and require regular maintenance. 

However, these pipelines are large structures, and it can be challenging to identify a leak when it occurs. If there is a delay sealing a gap, there could already be substantial groundwater contamination before an engineer resolves the problem.

3. Improper Hazardous Waste Disposal

It can be easy to improperly dispose of hazardous waste without realizing the devastating effect on groundwater. Pouring waste materials such as cooking and motor oils, garden chemicals, paints, and medicines down the drain means they can travel to groundwater wells. Homeowners should always take care when disposing of hazardous materials, taking them to a facility that can safely dispose of the potential contaminants.

On a more significant scale, industrial plants that discard their waste without utilizing proper methods can quickly cause groundwater pollution in a localized area. Businesses should ensure trained employees handle waste disposal duties and perform regular inspections to locate the source of any potential escape of pollutants into the surrounding environment.

A landfill is a disposal site for household or industrial waste. It’s vital to check it has clay or synthetic liners and leachate collection systems that help protect groundwater. Older sites do not use these safeguards, allowing chemicals and other pollutants to mix with groundwater. 

This problem is particularly severe when heavy rains or large amounts of surface water make it easier for groundwater contaminants to travel through gaps and overground. All closed landfills need an impermeable cover to reduce the risk of pollutants escaping when the site is no longer in use.

3. Agriculture and Farming

The agriculture and farming industries use considerable amounts of pesticides and chemicals to produce their goods. Herbicides, rodenticides, avicides, and many more chemicals are crucial elements of crop production. 

Pesticides can remain present in groundwater for months or years, presenting a health risk for extended periods. Animals are also a vital element in many agricultural and farming processes, and their waste materials are an additional source of potential groundwater contamination.

Nitrates and bacteria that mix with groundwater can be disastrous for wildlife and people who use this as a drinking source. Because many agricultural activities occur in rural communities, and groundwater is the drinking source for 99% of the US rural community, this problem could have catastrophic effects on the local population.

4. Mining and Quarrying 

Mining and quarrying use heavy-duty machinery to break up ground and rocks that can contain contaminants. Many quarrying locations cover many miles, increasing the risk of polluting a substantial-sized area. 

By digging into the ground, quarry firms can encourage groundwater contamination underneath the surface, making it more challenging to identify and rectify the problem. Even when the mine or quarry is no longer in use, rainwater can strip harmful pollutants from the surface of rocks, allowing them to flow into the earth and mix with groundwater.

5. Natural Gas Drilling

Industrial firms use a process known as fracking to drill for natural gas. This technique is controversial because experts are not entirely sure of the long-term effects of using such a destructive drilling process. Fracking companies blend chemicals with water and push the mixture into gaps in the ground to access the natural gas.

EPA officials are still determining if fracking causes groundwater pollution.

6. Unsafe Storage Tanks

Many homeowners use oil tanks to store the fuel for their home heating supply, but these storage solutions require regular inspections to ensure they are in good condition. Oil leaks can be difficult to clean after making contact with the ground and can be a significant source of pollution.

Industrial businesses commonly use large chemical storage tanks that contain hazardous liquids. Even a small crack in the tank lining could leak groundwater contaminants into the surrounding area. There are strict regulations to reduce the risk of leakage in industrial plants.  

7. Safeguarding Your Water Supply


There are many sources of groundwater contamination that are out of your control. However, there are also strict EPA regulations that water suppliers must follow before delivering water to your home. You can further safeguard your water supply by installing a water filter that removes harmful contaminants before they come through your faucet.

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About the Author

George Simms is a Salt Lake City based plumber and contractor, with a focus on aiding homes and businesses (particularly farm) solve problems with hard and contaminated water. Walter is here to share his wealth of job experience and a knowledge of both modern and antique plumbing.

Last Updated on April 13, 2021