You can help protect groundwater even if you do not have a water well. Protecting groundwater becomes even more important if you do have a well, because you are the manager of your water system. Your practices as a home and property owner have a direct impact on the quality of water you obtain from your well.

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Groundwater—its depth from the surface, quality for use as drinking water, and chance of being polluted—varies from place to place. Much U.S. groundwater is safe for human use. However, groundwater contamination can and does happen, so well owners have to be vigilant in protecting water supplies. Well owners should test their water regularly and maintain wells to safeguard their drinking water.

Learn more about groundwater protection from the Groundwater Foundation, Find free tools and resources to get involved in protecting this vital resource. The Groundwater Foundation connects people, businesses, and communities through local groundwater education and action, making us all part of the solution for clean, sustainable groundwater.

Groundwater may contain some natural constituents that present health risks or aesthetic problems such as poor odor, taste, or appearance. However, it is usually treatable to meet safe conditions.

Natural contaminants can come from many conditions in the watershed or in the ground. Water moving through rocks and soils may pick up magnesium, calcium, and chlorides.

Some groundwater contains dissolved elements such as arsenic, boron, selenium, or radon—a gas formed by the natural breakdown of radioactive uranium in soil. Whether these natural contaminants are health problems depends on the amount of the substance present.

Some naturally occurring constituents in groundwater include:

  • Microorganisms. All groundwater, to great depth, is inhabited by naturally occurring microorganisms, mostly bacteria and archaeans. They participate in mineral cycles and energy exchange. Bacteria, viruses, parasites, and other microorganisms of potential health concern are sometimes found in groundwater. Shallow wells—those with water close to ground level—are at most risk. Some types of aquifer rock, such as cavernous limestone and fractured rock, are more likely to be vulnerable to these microbes. Runoff, or water flowing over the land surface, may pick up these pollutants from wildlife and soils. This is often the case after flooding or heavy precipitation events over vulnerable aquifers.

Symptoms of viral, bacterial or other microbially induced illness include nausea and diarrhea. These can occur shortly after drinking contaminated water. The effects could be short-term, yet severe (similar to food poisoning), or might recur frequently or develop slowly over a long time.

  • Radionuclides. Radionuclides are radioactive elements such as uranium and radium. They may be present in underlying rock and groundwater. Some aquifers may have uranium diffused through them in mineable quantity, or uranium can be confined to shale or metamorphic rock layers. Drilling cuttings and fluids from hydrocarbon extraction from shales bring long-buried radionuclides to the surface. Consuming radionuclides over many years can contribute to cancer. Radon—a gas that is a natural product of the breakdown of uranium in the soil—can pose a threat. Radon is most dangerous when inhaled and may contribute to lung cancer. Radon is less dangerous when consumed in water, but remains a risk to health.
  • Nitrates and nitrites. Although high nitrate levels are usually due to human activities, they may be found naturally in groundwater. They come from the breakdown of nitrogen compounds in the soil and are then picked up by flowing groundwater. Drinking large amounts of nitrates and nitrites is particularly threatening to infants (for example, when mixed in formula).
  • Heavy Metals. Underground rocks and soils may contain arsenic, cadmium, chromium, lead and selenium. However, these contaminants are not often found in household wells at dangerous levels from natural sources.

Some human activities that can pollute ground water include:

  • Improper use of fertilizers, animal manures, herbicides, insecticides, and pesticides
  • Improperly built or poorly located and/or maintained septic systems for household waste water
  • Heavy construction and mining
  • House plumbing involving certain materials such as lead and copper
  • Leaking or abandoned underground storage tanks and piping
  • Storm water drains that discharge chemicals to groundwater
  • Improper disposal or storage of hazardous household wastes
  • Chemical spills at local industrial sites.

Bacteria and nitrates. These pollutants are found in human and animal wastes. Septic systems must be carefully maintained and animal manures managed to prevent pollution. Sanitary landfills and garbage dumps are also sources. Children and some adults are at extra risk when exposed to waterborne bacteria. These include the elderly and people whose immune systems are weakened due to, for instance, to a chronic illness or treatments for cancer. Fertilizers can add to nitrate problems. Nitrates cause a health threat in very young infants called “blue baby” syndrome. This condition disrupts oxygen flow in the blood.

Fertilizers and pesticides. The chemicals used in these products may end up in groundwater. Such pollution depends on the types and amounts of chemicals used and how they are applied. Local environmental conditions (soil types, seasonal snow, and rainfall) also have an affect. Many fertilizers contain forms of nitrogen that can break down into harmful nitrates. Some underground agricultural drainage systems collect fertilizers and pesticides. This polluted water can pose problems to groundwater and local streams and rivers. In addition, chemicals used to treat buildings and homes for termites or other pests may also pose a threat.

Heavy metals. Activities such as mining and construction can release large amounts of heavy metals (including radioactive uranium) into nearby groundwater sources. Some older fruit orchards may contain high levels of arsenic, once used as a pesticide, and bromine. At high levels, these metals pose a health risk.

Industrial products and wastes – Many harmful chemicals are widely used in local business and industry. These can become drinking water pollutants if not well managed. The most common sources of such problems include factories, gas stations, dry cleaners, leaking underground storage tanks and piping, and landfills and waste dumps.

Household wastes. Improper disposal of many common products can pollute groundwater. These include cleaning solvents, used motor oil, paints, and paint thinners. Even soaps and detergents can harm drinking water. These are often a problem from faulty septic tanks and septic leaching fields. Here are some tips:

#1 – Identify hazardous substances
#2 – If in doubt, check with your local waste authority
#3 – Ask your local waste authority about proper disposal
#4 – Don’t put hazardous substances down the drain or in the garbage
#5 – Store hazardous materials properly in sealed containers and secure places
#6 – Don’t over apply fertilizers, weed killers, or pesticides.

Lead and copper. Household plumbing materials are the most common source of lead and copper in home drinking water. Corrosive water may cause metals in pipes or soldered joints to leach into tap water. Your water’s acidity or alkalinity (measured as pH) greatly affects corrosion. Temperature and mineral content also affect corrosiveness. Lead can cause serious damage to the brain, kidneys, nervous system and red blood cells. Even in relatively low amounts, these metals can be harmful.

Learn more about the U.S. EPA’s maximum contaminant levels for various substances.

When building or modifying a well

    1. Hire a qualified water well contractor for any new well construction or modification
    2. Work with your contractor and environmental health professionals to understand your area and to avoid contaminated areas.
    3. Slope ground away from the wellhead so that surface runoff drains away from the well.

Preventing problems

    1. Install a locking well cap or sanitary seal to prevent unauthorized use of, or entry into, the well.
    2. Do not mix or use pesticides, fertilizers, herbicides, degreasers, fuels, and other pollutants near the well.
    3. Never dispose of wastes in dry or abandoned wells.
    4. Have a qualified septic system service provider pump and inspect your septic system as often as your local health department recommends.
    5. Avoid disposing of hazardous substances in your septic system.
    6. Take care in working or mowing around your well so as not to damage the wellhead or your water distribution line, or spill any hazardous substance such as fuel or motor oil on the ground.
    7. Actively advocate to protect the groundwater quality in your area to prevent contamination of your well and your neighbors.

Maintaining your well

  1. Each month, check visible parts of your well system for problems such as:
    • Cracking or corrosion
    • A broken or missing well cap
    • Settling and cracking surface seals.
  2. Have the water tested regularly.
  3. Keep accurate records in a safe place, including:
    • Your construction contract and reports
    • Maintenance records, such as those on disinfection or well cleaning
    • Any use of chemicals in the well
    • Water testing results.

After a flood

  1. Stay away from the well pump while it is flooded to avoid electrical shock
  2. Do not drink the water from the well or use it for washing to avoid becoming sick
  3. Get help from a qualified water well contractor or pump installer to:
    • Clean and turn on the pump
    • Flush the well
    • Disinfect the well
    • Perform any other necessary maintenance

Learn more about water well flooding

When closing a well

  1. Do not allow the well casing to be cut off below the ground surface
  2. Hire a qualified water well contractor to fill or seal the well.

Learn more about protecting this precious resource at the Groundwater Foundation. We all rely on groundwater in some way, and groundwater relies on us to protect it. Learn more, get involved – collectively we make a difference!

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