What Is Groundwater? How Does Groundwater Get Contaminated?
November 2, 2018
Considered one of our hidden resources (since it’s underground) groundwater is part of the natural hydrologic cycle, which involves the saturation of water through the ground surface. Water from rain, snow, and melted ice flows into rivers, streams, and oceans, but much of it gets absorbed by the earth.
Source: Wikimedia Commons
Groundwater can be found in either the unsaturated zone or the saturated zone.
As the water moves down through the unsaturated zone (open spaces in rock and soil that contain water and air), it eventually reaches the water table (the top of the saturated zone). The water table can be right below the surface or hundreds of feet below. The saturated zone is filled with water and lies beneath the unsaturated zone.
Groundwater can stay in the saturated zone or enter into marches, lakes, springs, and streams where the water gets evaporated and falls back to earth in the form of precipitation to begin the process all over again.
How is Groundwater Used?
Groundwater is used for many different purposes, including agriculture, washing, and drinking. Whether it comes from public water supplies or directly from a private well, groundwater accounts for about 35% of household water needs for urban areas and about 95% of the water supply for rural areas (EPA).
For a long time, groundwater was considered to be uncontaminated because the layers of sand, gravel, and rock acted as a natural filtration system. Since the 1970s, however, every single state in the nation has reported cases of contaminated groundwater. While layers of rock, sand, and gravel do provide natural filtration, we know that some contaminants can still pass through and contaminate our groundwater supplies.
According to the EPA, “Between 1971 and 1985, 245 ground-water-related disease outbreaks, with 52,181 associated illnesses, were reported.” Many times pesticides, which are known carcinogens, have been detected in groundwater supplies.
How Does Groundwater Get Contaminated?
Groundwater can be contaminated in a variety of ways, including getting absorbed through the surface of the ground, in the ground above the water table, and in the ground below the water table.
Ground Surface Contaminations
- Infiltration of polluted surface water
- Land disposal of wastes
- Sewage sludge disposal
- De-icing salt use and storage
- Animal feedlots
- Fertilizer and pesticides
- Accidental spills
- Airborne source particulates
Above Water Table
- Septic tanks, cesspools, and privies
- Holding ponds and lagoons
- Sanitary landfills
- Waste disposal in excavations
- Underground pipeline leaks
- Artificial recharge
- Sumps and dry wells
Below Water Table
- Waste disposal in wells
- Drainage wells and canals
- Underground storage
- Exploratory wells
- Abandoned wells
- Water supply wells
- Groundwater withdrawal
Common Groundwater Contaminants
- Septic tanks, cesspools, and privies
- Surface impoundments
- Agricultural activities (fertilizers, pesticides, etc.)
- Underground storage tanks
- Abandoned wells
- Accidents and illegal dumping
- Highway de-icing
The main factors for whether groundwater gets contaminated is how much contaminant there is and how far it has to travel before reaching the groundwater.
Unfortunately, since groundwater is hidden from view, contamination can go undetected for years. Normally, a problem is only detected after it has caused extensive contamination. The clean-up process is often costly, complicated, and sometimes impossible.
What to Do After Contamination Has Occurred?
According to the EPA, a community normally has five options when their groundwater has become contaminated:
- Contain the contaminants to prevent migration from the source.
- Withdraw the pollutants from the aquifer.
- Treat the groundwater where it is withdrawn or at its point of use.
- Rehabilitate the aquifer by either immobilizing or detoxifying the contaminants while they are still in the aquifer.
- Abandon the use of the aquifer and find alternative sources of water
All of these options are very expensive. The best and cheapest way to maintain clean groundwater is to prevent contamination in the first place.
How to Prevent Groundwater Contamination
The U.S. Environmental Protection Agency (EPA) helps protect groundwater supplies by enforcing a number of laws, including:
- The Safe Drinking Water Act regulates the contaminants in drinking water.
- The Resource Conservation and Recovery Act regulates the storage, transportation, treatment, and disposal of solid and hazardous wastes.
- The Comprehensive Environmental Response, Compensation, and Liability Act (Superfund) authorizes the governments to clean up contamination caused by chemical spills and hazardous waste sites that could (or already do) pose threats to the environments.
- The Federal Insecticide, Fungicide, and Rodenticide Act authorizes EPA to control the availability of pesticides that have the ability to leach into groundwater.
- The Toxic Substances Control Act authorizes EPA to control the manufacture, use, storage, distribution, or disposal of toxic chemicals that have the potential to leach into groundwater.
- The Clean Water Act authorizes EPA to make grants to the states for the development of groundwater protection strategies and authorizes a number of programs to prevent water pollution from a variety of potential sources.
Source: U.S. EPA
These federal laws focus on groundwater contamination on a national level. It’s also extremely important that there be state, local, community, and individual groundwater protection practices and strategies.
How to Help Your Community Prevent Groundwater Contamination
- Know if your drinking water comes from groundwater.
- Get information in your state’s wellhead protection program. Learn who has what groundwater responsibility in the state. What kind of tests or procedures are used to test or monitor groundwater quality.
- Your community has a number of different tools at its disposal to protect its groundwater, including:
- zoning ordinances and decisions
- developing land-use plans
- overseeing building and fire codes
- implementing health requirements
- supplying water, sewer, and waste disposal services
- using police powers to enforce regulations and ordinances
- Help your community develop policies and programs to protect its groundwater.
- Get your water tested and plumbing inspected by a professional.
- If you are a business, learn what you can do to protect drinking water sources.
Water Testing and Purification
If you want the best water quality for your home and family, consider testing your water and installing a water purification system if necessary.
Contact the professionals at OnTime Service to test your water and recommend various water treatment systems to improve the quality of your drinking water.
Speak with the water quality experts at OnTime Service for more information on protecting and purifying your groundwater supply.
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