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Wells provide Idahoans with ground water for their drinking water and household and irrigation water needs. A private (domestic) well supplies water to one a few houses while a public water system supply well provides water to several houses, a community, or a business or school and is operated by an entity. There are approximately 2,000 public drinking water systems in Idaho serving approximately 1.3 million citizens.

Whether you use a private well or are connected to a public drinking water system, the water that flows from your tap is likely ground water. If your water is from a public system, you rely on your water provider to ensure your water is safe to drink. Public water systems are regulated by the Safe Drinking Water Act.  However, if you use a private well, these wells are not regulated under the Safe Drinking Water Act and well owners are responsible for ensuring their water is safe. Since both public and private wells are drilled into ground water, the same contaminants that are present in ground water, such as nitrate and arsenic, can be also present in well water.

  • Private
  • Public

Nitrate, bacteria, and arsenic are three of the most common ground water contaminants in Idaho. Private wells should be tested for nitrate and bacteria at least once per year (test for nitrate more frequently if a pregnant woman or an infant will be using the water). Contact your DEQ regional office or public health district to learn about ground water quality constituents of concern in your area.

You can collect water samples yourself and have them tested by an Idaho-certified laboratory. For instructions, including how to get the sample containers, how to collect the sample, and the timeframe for transporting samples, contact your DEQ regional office, or public health district. An environmental consultant can also sample for you.

A sudden change in the taste, odor, or appearance of your drinking water may indicate contamination or a problem with your system that may warrant testing. Contact your local public health district for advice.

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If your well water tests positive for a contaminant, discuss your test results and determine any health risks with your local public health district.

If your water is contaminated to a point that it may harm your health, fix the problem as soon as possible. You may need to find an alternative drinking water source (for temporary or permanent use), disinfect your well, repair your system, or install a water treatment device.

You may need to purchase several treatment units or combine them into one system to treat multiple water quality issues. Research possible devices carefully to find the best solution and contact the National Sanitation Foundation (NSF) to ensure the treatment system is certified to perform as stated or has the NSF seal.

If you have elevated levels of nitrate, arsenic,  or uranium in your water, do NOT boil it. Boiling concentrates these contaminants.

Proper well design, construction, and maintenance can reduce the chance that surface contaminants will get into your well water. Identify and remove sources of contaminants near the well such as fertilizers, animal wastes, pesticides, and other sources of contamination. If a contaminant source is found to be impacting a well, you may need to hire a licensed well contractor to evaluate possible modifications to the well that may improve your water quality.

Have the well inspected by a licensed well contractor if it is old or is structurally compromised.  Repairing the well or constructing a deeper well may prevent contaminants from entering the well.  Contact the Idaho Department of Water Resources to find licensed well drillers in your area.

Inspect your well and surrounding area frequently and follow the guidelines below when working on or near a well.

Ensure your well is properly installed and maintained by following these steps:


  • Before drilling, research local conditions and potential contaminant sources, such as neighboring and historical land uses. Sources of information on ground water quality include the regional DEQ and the local public health district.
  • Hire a licensed well driller for construction, modification, abandonment, and closure. Idaho law requires all well drillers to be licensed and obtain a permit before drilling. Some wells drilled prior to this requirement may need to be updated.


  • Keep accurate records of well maintenance.
  • If you are drilling a new well, get a copy of the log from the well driller upon completion. Logs for wells drilled since 1987 are on file with the Idaho Department of Water Resources.


  • Ensure the well casing, cap, and surface seals are intact and the top of the well at least 18 inches above the ground.
  • Verify the area around the well is sloped to drain surface water away from the well.
  • Make sure the valves are set properly to prevent backflow.
  • Take precautions when working on or near a well.
  • Avoid mixing or using fertilizers, herbicides, fuels, motor oil, and other pollutants near the well.
  • Do not pile snow, leaves, or other materials around the well.
  • Take care when working or mowing around the well to avoid damaging the casing.


  • Properly locate your septic system to reduce the potential of contaminant migration from the septic system.
  • Properly maintain your septic system and never use it to dispose of hazardous materials.
  • Avoid driving on or planting trees near your septic system drainfield.
  • Pump and service your septic system every two to three years.

A public water system (PWS) well supplies ground water to the public through pipes or other constructed conveyances. A public water system well must have at least 15 service connections or regularly serves an average of at least 25 individuals at least 60 days out of the year.

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Review the source water assessment(s) completed for your public water system. The Safe Drinking Water Act requires assessments of all recognized public water sources in Idaho. These reports will the zone of contribution, identify the significant potential sources of contamination, and determine the likelihood that the water supply will become contaminated. Access your water system report.

DEQ is authorized to administer Idaho’s Drinking Water Program through the federal Safe Drinking Water Act and the “Idaho Rules for Public Drinking Water Systems” (IDAPA 58.01.08).

There are approximately 2,000 public drinking water systems in Idaho. Many other Idaho citizens get their drinking water from private wells. These wells are not regulated under the Safe Drinking Water Act; well owners are responsible for ensuring their water is safe. 

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