Why it is Important to Know What is in Your Well Water
Do you know where your drinking water comes from or what is in it? 30% of Idahoans have made private well water their primary source of water. Due to inadequate water testing, you may be exposed to ground water contaminants that pose health risks. How long has it been since you had your well water tested? If you are a private well owner, you are responsible for ensuring that the well water is safe to drink!
A variety of contaminants, both naturally occurring and human-caused, can be found in Idaho’s groundwater. Depending on the contaminant and concentration, there can be short- and long-term health and developmental effects. Testing your drinking water is the only way to know what’s in your water. Once you know, then you can take steps to learn what is causing the contamination and determine the best treatment and maintenance options.
While your water may appear safe, harmful levels of contaminants occur at such low concentrations that they often cannot be tased, seen, or smelled. This means regular testing and maintenance are necessary to protect the health of your family. You should test your well water once a year for bacteria and nitrates and once every three to five years for everything else. Use the Groundwater Quality Near Me map to aid in determining what contaminants to test for. If undesirable levels of contaminants show up in your water, contact The Department of Health and Welfare’s Environmental Health Program at EH@dhw.idaho.gov or 1-800-445-8647 to determine the best method to fix the problem and if you have questions about your well water testing results. Also review our well water testing flow charts to navigate your water testing results here.
Is my well water safe from these contaminants?
A chemical found in most fertilizers, manure, and liquid waste discharge from septic tanks. Natural bacteria in soil can
convert nitrogen into nitrate. Rain or irrigation water can carry nitrate down through the soil into groundwater. Nitrates lessen the ability of bloods to carry oxygen.
For more information, please review our Nitrate brochure.
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken a nitrate water sample that has come back elevated, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Total Coliform (TC) Bacteria are commonly found in soil, surface water, on plants, and in the intestines of humans and warm-blooded
animals. TC bacteria are an indicator that contamination has entered the water. Most TC bacteria are not harmful. However, some can make you sick. A person that has been exposed to these bacteria may have an upset stomach, vomiting, fever, or diarrhea. Children and the elderly are more at risk from these bacteria.
For more information, please review our Bacteria Brochure.
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken a total coliform water sample that has come back present, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Arsenic is a chemical element that naturally occurs in the earth’s mineral deposits and dissolves in groundwater. Arsenic in drinking water may have harmful health effects depending on how much you consume and how sensitive you are to it. Long-term exposure to low levels of inorganic arsenic in drinking water is known to cause human health problems including: cancer, thickening and discoloration of the skin, problems with blood vessels, high blood pressure, heart disease, nerve effects including numbness and/or pain.
For more information, please review our Arsenic Brochure
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken an arsenic water sample that has come back elevated, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Fluoride is a naturally occurring mineral that is released from rocks into the soil, water, and air. Fluoride helps protect your teeth by strengthening the outer enamel surface. If you get too little fluoride, your teeth might weaken and develop cavities. Cavities can lead to pain, tooth loss, infections, and other health problems.
Excess amounts of fluoride ions in drinking water can cause dental fluorosis, skeletal fluorosis, arthritis, bone damage, osteoporosis, muscular damage, fatigue, joint-related problems, and chronicle issues.
For more information, please review our Fluoride Brochure.
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken a fluoride water sample that has come back above or below recommended levels, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Manganese is a naturally occurring mineral in rocks and soil in regions of Idaho and can be found in drinking water sources. You might suspect manganese is in your water if it is discolored (brownish red), causes staining of plumbing fixtures or clothing, or has an off-taste or odor. Children and adults who drink water with high levels of manganese for a long time may have problems with memory, attention, and motor skills. Infants (babies under one year old) may develop learning and behavior problems if they drink water with too much manganese in it.
For more information, please review our Manganese Informational Sheet.
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken a manganese water sample that has come back elevated, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Selenium is a trace mineral needed in small amounts for good health. Short-term ingestion of high concentrations of selenium may cause nausea, vomiting, and diarrhea.
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken a selenium water sample that has come back elevated, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
pH is a measurement of how acidic/alkaline water is. In its purest form, water has a pH of 7, which is at the exact center of the pH
scale. A change in pH can change the chemical state of contaminants. Most water for use has a pH of between 6.5 and 8.5.
The danger of more acidic water – when the pH is less than 6.5 – is that it can leach metals from the well and from the pipes that bring you water. These metals include lead, manganese, copper and iron, and they can be toxic in large amounts.
When the PH of water becomes more basic - when the pH is greater than 8.5, water taste can become more bitter. This elevated pH can also lead to calcium and magnesium carbonate building up in your pipes. While this higher pH doesn't pose any health risks, it can cause skin to become dry, itchy and irritated.
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken the pH of a water sample that has come back below 6.6 or above 8.5, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Sulfates are a group of mineral salts that are natural or human-made. These salts can be found in soil, air, and water. People who are not used to drinking water with high sulfate can get diarrhea and dehydration from drinking the water. Infants are often more sensitive to sulfate than adults.
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken a sulfate water sample that has come back elevated, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Uranium is a naturally occurring, mildly radioactive compound commonly found in rocks, soil, and water. Uranium in well
water is caused by uranium in the rock where the well is drilled. Exposure to elevated levels of uranium over a long period of time can damage your kidneys. However, the kidney can recover from this damage after exposure is reduced or eliminated.
For more information, please review our Uranium Brochure.
Learn how to take a proper water sample by watching this video (Pruebas de Agua de Pozos Privados), or would you rather read the instructions here.
You have taken a uranium water sample that has come back elevated, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Lead can enter drinking water when a chemical reaction occurs in plumbing materials that contain lead. Corrosion is more severe when water has high acidity or low mineral content. Household plumbing fixtures, welding solder, and pipe fittings made prior to 1986 are more likely to contain lead. High levels of lead in tap water can cause health effects if the lead in the water enters the blood and causes high blood lead level. It can cause damage to the brain and kidneys, and can interfere with the production of red blood cells that carry oxygen to all parts of the body.
For more information, please review our Lead Facts Sheet.
Learn how to take a proper water sample by watching this video (Pruebas de Plomo y Cobre en el Agua), or would you rather read the instructions here.
You have taken a lead water sample that has come back elevated, what next? Review our sampling flow chart here.
You need more information on how to treat your water for contaminants? We have information for you here.
Private wells can be a safe and reliable source of drinking water. In Idaho private well owners are responsible for ensuring their water is safe to drink. All private well owners should test their drinking water to ensure that it is safe to drink and regularly maintain their wellhead.
Some private wells may have high levels of contamination from bacteria, naturally occurring, or man-made chemicals that can be harmful to your health. Use the resources below to find out what to test for, how often to test, and how to keep your water safe. To learn the best ways to take a water sample, please review the videos linked in the above contaminant list or directly below.
Learn how to take a proper water sample by watching this video Pruebas de Agua de Pozos Privados, or would you rather read the instructions here.
Learn how to take a proper water sample for lead and copper by watching this video Pruebas de Plomo y Cobre en el Agua, or would you rather read the instructions here.
Ground Water Quality Near Me
The Idaho Department of Health and Welfare created the interactive map below to make private well owners aware of existing ground water quality data in their area and promote regular ground water quality testing. Ground water quality at privately owned wells is not regulated by the State of Idaho. Private well owners are responsible for maintaining their well and ensuring the water is safe to drink, which can be accomplished through periodic testing.
View the map here
About the Map
Private wells displayed on the map were sampled by the Idaho Department of Water Resources , the Idaho Department of Environmental Quality , the Idaho State Department of Agriculture , and private well owners between 2004-2020. Each well contains the most recent sampling results for up to nine chemicals, the year it was sampled, the sampling agency, and the well depth if it is known.
Agencies may have additional data that has not been included as part of this map. Additionally, more recent data may exist for certain chemicals that were unavailable at the time this map was published. Contact the individual sampling agencies for more information.
Find a location and set your search radius
Enter an address or place of interest in the search field in the panel to the left of the map. The map will default to locating wells within a two mile radius of your location. Use the text box or slider to expand the search radius in miles. Alternatively, click the set location icon , located next to the magnifying glass icon, and click on the map to set a location if the address is unknown.
View results
Wells found within the designated search radius are listed below the slider. Wells over a primary drinking water standard are titled as Primary Standard Exceeded. Click on individual search results, or click directly on a well symbol to see the data.
Note multiple agencies may have sampled the same well, but assigned a different site ID. Additionally, the same agency may have sampled the same well for different chemicals in different years. Use the arrow in the pop up window after clicking on a well to view all available data.
Drinking Water Standards
Primary
Arsenic, fluoride, nitrate, selenium, and uranium have primary drinking water standards. Public drinking water systems are regulated by DEQ and are required to comply with these, and other standards not represented here, to protect human health. The units of measure (e.g., ug/L or mg/L) provided in the following table may not match the units of measure on the laboratory report provided to you. If this is the case, results will need to be converted to make the best use of this table. If you need assistance converting or interpreting results, call the laboratory that did the analysis or IDHW's Environmental Health Hotline at 1-800-445-8647 or radon@dhw.idaho.gov.
Chemical |
Primary Standard |
Health Effects |
| Arsenic | 10 ug/L | Long term exposure to arsenic from drinking water can cause cancer and skin lesions. |
| Fluoride | 4 mg/L | Depending on the length and amount of exposure, fluoride can stain teeth, increase risk of broken bones, or cause pain and tenderness in joints and bones. |
| Nitrate | 10 mg/L | Nitrate can be converted to nitrite in humans where it lessens the ability of blood to carry oxygen. This is of greatest concern for infants, pregnant, and nursing women. |
| Selenium | 0.05 mg/L | Prolonged exposure to elevated levels of selenium can cause fingernail or hair loss, numbness in extremities or circulation problems. |
| Uranium | 30 ug/L | The greatest risk is kidney damage, especially for young children because their bodies are still developing. |
| Bacteria* | ZERO |
Most coliform bacteria do not cause disease, but they can indicate the presence of other harmful bacteria such as Escherichia coli (E. coli). E. coli can cause nausea, vomiting, fever, and diarrhea. * Monitoring results related to bacteria were not included in this map because the presence of bacteria is typically a result of site specific conditions rather than a wide scale problem. |
Secondary
Chloride, fluoride, iron, manganese, and sulfate have secondary drinking water standards. These guidelines were established by EPA to manage aesthetic considerations of drinking water such as taste, color and odor. These contaminants are not considered to present a risk to human health at the secondary levels.
Chemical |
Secondary Standard |
Health Effects |
| Chloride | 250 mg/L | Salty taste |
| Fluoride | 2 mg/L | Tooth discoloration |
| Iron | 0.3 mg/L | Rust color, sediment, metallic taste, reddish or orange staining |
| Manganese | 0.05 mg/L | Black to brown color, black staining, or bitter metallic taste |
| Sulfate | 250 mg/L | Salty taste |
Water Quality Testing
Water samples can be taken by homeowners and submitted to a laboratory for testing. Click here for a list of Idaho-certified laboratories . The laboratory, your DEQ regional office , or public health district can tell you how to obtain the necessary sample containers, how to take the sample, and how quickly you must get the sample to the laboratory. If you do not want to take the samples yourself, an environmental consultant can conduct the sampling for you.
Testing Frequency
Testing |
Chemical |
| Once a Year | Bacteria, Nitrate |
| Once every 3-5 years | Arsenic, Fluoride, Selenium, Uranium |
| If your water tastes, smells, or looks strange | Chloride, Manganese, Sulfate |
| If you live in an agricultural area and/or have underground tanks with petroleum | Pesticides, Petroleum |
| If you have a formula-fed infant under 6 months | Manganese |
Fix a Problem
If there is a problem with your drinking water, you may need to disinfect your well, repair your system, find an alternative drinking water source, and/or install a water treatment device to remove contaminants. When installing a treatment system, look for NSF International certified treatment devices. You need more information on how to treat your water for contaminants? We have information for you here.
Treatment Resources
Protecting Your Wellhead
Well maintenance and managing potential sources of contamination are very important to keep your water safe.
Inspect the well and surrounding area regularly:
- Are the well casing, well cap, and surface seals intact and in good shape? Is the top of the well at least 18 inches above the ground?
- Is the area around the well sloped to drain surface water away from the well?
- Are irrigation valves set properly to prevent backflow?
Fertilizers, animal waste, pesticides, septic systems and other potential sources of contamination should be located and managed so they do not contaminate the 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 around the well to avoid damaging the casing.
- Properly locate and manage septic systems.
Contribute Data
Private well owners utilizing the Idaho Bureau of Laboratories (IBL) as their testing laboratory have the opportunity to participate in citizen science by allowing their results to be displayed publicly on this map. Citizen science is the voluntary involvement of the public in scientific research, in this case data collection. This work helps professional scientists and other private well owners to better understand ground water quality in Idaho.
If you own a private well, consider becoming a citizen scientists by granting permission on IBL’s submission form to display your tests results on this map. There are more than 3,000 wells displayed on the map currently. Note data collected by citizen scientists may not have been collected under a Quality Assurance Project Plan (QAPP), a written document that outlines the procedures a monitoring project will use to ensure the samples collected are of high enough quality to meet project needs. Using a QAPP is not required to display your results, but resources are available online. Click here for more information.