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Answers to your questions about groundwater

Approximately two-thirds of the people in Wisconsin obtain their drinking water from groundwater. If your water comes from a well, public or private, you’re one of these people! Groundwater is also essential for Wisconsin’s farm and business communities.

Groundwater is replenished by rain and melting snow that percolates through the soil. Most wells in Wisconsin tap groundwater, which is usually less than 50 feet below the ground surface and originates within a few miles or less from the well. Groundwater feeds surface water resources, such as lakes and rivers, providing a base flow level and helping to keep water levels consistent.

Groundwater problems

What contaminants are most frequently found in Wisconsin groundwater?

Both naturally occurring and chemical contaminants have been found in Wisconsin’s groundwater.

Naturally occurring contaminants are those that may be present in Wisconsin’s groundwater due to natural geologic factors, such as mineral deposits, or other factors within the environment that are independent of any human activities. The most commonly detected naturally occurring contaminants are arsenic, bacteria, barium, chloride, copper, fluoride, hydrogen sulfide, iron, lead, manganese, some parasites and viruses, radium, radon, sulfate, uranium and zinc.

Any chemicals used by humans have the potential to become groundwater pollutants. Some of these items, such as arsenic, also occur naturally but when used and improperly disposed of, they become a threat to groundwater quality. Bacteria, nitrate, arsenic, alachlor, atrazine, benzene, chloroform, toluene, trichloroethylene (TCE), parasites and viruses are some of the most common chemicals detected in groundwater.

Both naturally occurring and chemical contaminants can become of concern to human health when concentrations go above established health advisory levels. The health advisory level, or the maximum contaminant level (MCL), are set by federal and state government for drinking water systems or the groundwater enforcement standards (ES) for groundwater. Many brochures with more information on common contaminants and recommendations for private well maintenance are available.

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Should I drink water that exceeds groundwater standards or health advisory guidelines?

DNR staff recommend that you do not drink water exceeding the health advisory guidelines, but the choice is ultimately yours. Bacterial contamination can cause acute illness in a short period of time, so if your water tests positive for bacteria, you should stop drinking the water and contact a water professional for advice. For chemical contamination however, the effect on any person will depend on the type and degree of contamination, the amount of water consumed and the person’s resistance to that contamination, which depends on a person’s age and other coexisting health problems.

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Is it possible that my well water is making my livestock or me sick?

Waterborne disease caused by bacteria, viruses or chemicals is possible. Anytime you or your livestock become ill, feel tired or sluggish, you should contact your family doctor or veterinarian. If it is determined your water supply could be the cause of the illness, he or she should contact your local health department.

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Can you tell me why my water suddenly has a strange odor or taste?

Without sampling and analyzing the water, it’s often impossible to tell precisely why it has a strange odor or taste. If you notice a sudden change in your water, there may be reason for concern. Sudden changes occur for a number of reasons, such as large rainfall events flushing contaminants into or through the groundwater aquifer, where they may enter your well and water supply.

Because contaminants from distant sources may also move into your well through normal groundwater flow through the aquifer, it is recommended that you test your private well annually and whenever you notice a sudden change. You can also try “self-diagnosis” with “What’s Wrong with my Water?”.

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Are there shortages of groundwater in Wisconsin?

Generally, groundwater by volume is ample throughout most of the state. In a few areas, specific geologic formations or locally high use may make it difficult to get large volumes of water. In some areas, clean groundwater may be limited due to contamination.

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Groundwater responsibility

Why isn’t every private well in the state tested?

Well owners are responsible for testing their individual well. Current regulations require that every newly drilled private well in Wisconsin be tested for the most common contaminant, bacteria. DNR drinking water and groundwater specialists also recommend that new wells be tested for nitrate. Depending on nearby contaminant sources and land use, further testing may be advised.

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What state agencies regulate and protect groundwater quality and other items related to groundwater use Wisconsin?

A number of state agencies have authority under Wisconsin statutes and administrative rules to regulate activities that can affect groundwater quality. The agencies also provide information and technical assistance to local groundwater protection efforts. For example, the Department of Safety and Professional Services (DSPS) regulates on-site wastewater treatment systems. The Department of Agriculture, Trade and Consumer Protection (DATCP) regulates pesticide and herbicide mixing sites and application, livestock health issues, and fertilizer storage, handling and mixing. DATCP also periodically surveys groundwater for contamination.

The DNR regulates wastewater treatment systems, confined animal feeding operations, landfills and hazardous waste disposal sites, spills, well construction, sealing and pump installations. The DNR trains and licenses well drillers and pump installers, funds groundwater research, troubleshoots regional groundwater contamination, assists in local source water protection efforts, and coordinates groundwater work across state agencies and the University of Wisconsin system.

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Can I contaminate my drinking water supply or that of a neighbor by using chemicals on my lawn or by pouring waste oil or gasoline on the ground or disposing of contaminates down my septic system?

Yes, it is possible to contaminate your well, your neighbor’s well and the rest of the surrounding groundwater through the improper use or disposal of chemicals or septic waste. However if you follow the manufacturer’s application instructions carefully normal use of these chemicals should not cause groundwater quality problems. In general, DNR drinking water and groundwater staff recommend that you avoid heavy lawn chemical applications near any well. Avoid spraying near the well casing or cap. Avoid misuse or over-application. Also, keep your septic system properly maintained and do not dispose of chemicals or materials down the drain that can hinder the septic system’s working effectiveness.

Gasoline spills and leakage from underground storage tanks have been responsible for many contamination incidents. However, small amounts of oil or gasoline dripping from vehicles onto the ground surface usually do not cause serious groundwater quality problems. Soil and groundwater conditions, well construction and the condition of your well also play a major role in whether the well and the surrounding groundwater becomes contaminated.

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Who pays to clean up contaminated groundwater?

Complete groundwater cleanup is seldom possible and is always expensive. The general rule is to determine a responsible party for the contamination and require them to pay for cleanup. If a responsible party can’t be found or is unable to pay, then the state or federal government may be forced to accept the cleanup costs. Thus, we all pay indirectly through our taxes or higher product costs.

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How can I be sure my community’s water supply is safe now and in the future?

Community water systems are sampled and tested regularly. Contact your water utility about yearly monitoring or read their consumer confidence report (CCR). Ask if your system has a wellhead protection or source water protection plan in place or if your local government is considering the implementation of one. A wellhead protection plan is designed to protect a water supply for present and future generations. It involves identifying the area contributing recharge to a well, identifying potential contamination sources, and developing and implementing the plan to protect the identified recharge area from contamination. A source water protection plan is a similar plan for protection of surface water derived drinking water supplies. You can find out more by visiting source water protection.

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Are there limits on how much groundwater can be pumped?

Under current law, a high capacity well permit is required from the DNR for a well or combination of wells on a single property that pump over 70 gallons per minute.

There is however, no limit on the amount of groundwater that you can pump over 70 gal/min unless it would have an adverse effect on a water of the state.

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Groundwater solutions

What can I do if my well runs dry?

The best advice is to prevent this from happening through individual and community conservation efforts. However, if indeed your well does run dry there are three main options.

  • First, see if lowering your well pump would provide you with enough water. Purchase of a new well pump may be necessary depending on depth and pump capacity.
  • Second, you can deepen your existing well along with lowering the well pump.
  • Third, you can drill a new well in another location.

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How can I have my well tested for bacteria, nitrate or other compounds?

Private well owners are responsible for maintaining the quality of their water supply. Two publications can help get you started:

Certified laboratories can also help you with information, materials and instruction on sampling and testing your well. A list of certified labs is available from the DNR or check your local yellow pages.

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How often should I have my well tested?

You should have your well tested for bacteria and nitrates at least annually, or if changes in taste, color or odor occur.

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If my well was found to be contaminated, who can give me advice on corrective action?

Different contaminants require different actions. The well owner can carry out some; other actions may require professional expertise. Contact a local well driller or pump installer for advice on your particular contamination situation. They can provide advice on either rehabilitating your existing well or constructing a new well.

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What recourse do I have if someone contaminates my drinking water supply?

It is often difficult to trace a single source of groundwater contamination without extensive investigation. If you believe someone has contaminated the groundwater and your drinking water, keep a complete record of the situation. A DNR drinking water and groundwater specialist may be able to give general advice or determine if any regulations apply. Further groundwater sampling and hydrologic study may be necessary to determine the source of contamination and the steps needed to correct the problem.

If you can identify the source of groundwater contamination and prove negligence, you may want to consider legal action to recover damages. An attorney can advise you of your rights in individual cases.

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Are home water treatment units and water softeners effective in removing harmful contaminants from well water?

Water softeners are effective primarily in removing hardness and radium. Other types of home treatment devices are more effective in removing other contaminants. The DSPS has approved a large number of treatment devices. A list of specific contaminants and a defined range of effectiveness for each approved treatment unit is available at Homeowner Help or “What’s Wrong with my Water?” However, usually replacing your well is a better long-term solution to a drinking water contamination problem if the contamination source can’t be removed.

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If my well requires replacement due to contamination, how will I pay for it?

A private well owner is generally responsible for the costs associated with maintaining their own private water supply. Homeowners insurance doesn't typically cover well replacement or treatment costs - contact your insurance agent to be sure. The State of Wisconsin offers a Well Compensation grant program for low income well owners. The program is administered by DNR, and may pay up to 75 percent of costs for a replacement water supply if eligibility requirements are met. Well owners with an income level above $65,000 do not qualify, and grant funds must be approved prior to replacing your well, so contact the well grants manager before you start construction.

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What should I do if a well on my property isn’t being used?

Unused wells can be a safety hazard and can act as a conduit for groundwater contamination. The state well code contains requirements for the proper filling and sealing of unused private wells, in a procedure known as “well abandonment.” A local licensed well driller or pump installer can help you properly abandon unused wells on your property.

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What can I do as an individual to help protect the groundwater or reduce excessive use in my community?

An individual can take many actions to help protect and conserve groundwater.

Groundwater protection tips
  • Recycle and dispose of household waste properly.
  • Recycle used motor oil.
  • Recycle used antifreeze.
  • Avoid spilling gasoline on the ground.
  • Follow label direction on fertilizers and pesticides.
  • Mix chemicals safely and carefully.
  • Install back-flow preventers on faucets.
  • Participate in local Clean Sweep programs to get rid of old hazardous materials and chemicals.
  • Maintain your septic system properly.
  • Follow recommended Best Management Practices (BMPs).
Water conservation tips
  • Install low flow fixtures (toilet, showerhead, etc.).
  • Repair leaks and drips quickly.
  • Do only full loads of laundry or use water saving settings.
  • Reduce or eliminate lawn watering.
  • Reduce shower time.
  • Water plants or lawns only in the early morning.
  • Landscape with native or low water use plants.
  • Don’t run the water while brushing teeth or doing dishes.

If you would like more information on groundwater conservation and protection around the house, see our brochure:

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Where can I get more information?

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