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Private Well Testing

Did you know that if you drink water out of a private water supply, you should test your water source at least once each year and anytime the well is serviced or the water changes in look, smell or taste?

Did you know the contaminants that you should test for can be dependent on where you live in the state? The testing you need will depend on the actual source of your water, the historic and current land use practices, and your specific worries or concerns about your water and your overall health.

Please click on any of the questions linked below to view our guidance.

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Important information for well owners whose wells are in or near flood areas

Never consume water from a well if there is any chance the well has been impacted by flood waters. Contaminated water can cause severe illness.

Over the last few weeks, spring snow melt along with heavy rains have caused flooding in many locations across Iowa. Because of this, please be aware that any well in or near flooded areas may be impacted by flood waters.

Floods can cause water quality problems with water supply wells - even if your well isn't directly in the flooded area. During a flood, the increased groundwater loading nearby a well can cause well contamination. Contaminated surface water can also leak into a well through defects in the well's casing or physically run over the top of the well and cause direct contamination of the aquifer. 

It's important to keep in mind that flood water can contain infectious bacteria, viruses, agricultural or industrial chemicals, and other hazardous agents. Because of this, consuming contaminated water can cause serious illness - especially in infants, individuals with compromised immune systems, and our elderly population. Water testing is the only way to know if your well is affected. Please see our document named "What should I do when my well floods" for additional information.

The Iowa DNR has a Disaster Assistance webpage available at the following website: https://www.iowadnr.gov/About-DNR/Social-Media-Press-Room/Disaster-Assistance.

The State Hygienic Laboratory (SHL) at The University of Iowa has an information page available to help guide well owners whose wells may be affected by flooding. You can view the information at the following website: http://www.shl.uiowa.edu/news/wellflood.xml.

SHL also offers a wide range of well water tests to assist well owners determine if the water is safe to consume. For additional information or to order water sample test kits, call SHL at 866-421-4692, or visit the SHL website at: http://www.shl.uiowa.edu/env/privatewell/ordering.xml.

Iowa State University Extension Service has information to assist well owners whose wells may be impacted by flood waters. You can view the information at the following website: https://www.extension.iastate.edu/news/check-private-wells-contamination-after-flooding.

The National Groundwater Association has information about the concerns of well placements in flooded areas. It's available at the following website: http://wellowner.org/flooding-resources/.

Water System Council wellcare® information series also offers the following guidance for wells that may be affected by flooding:

Fact Sheets titled:

And informative videos titled:

NEW - Well Disinfection or Chlorination. The Centers of Disease Control and Prevention (CDC) has a webpage that provides information on how to disinfect your private water supply after a flood or other natural disaster. The information is available at the following link: Disinfecting Wells After A Disaster

The bottom line is if there is any doubt about the safety of your drinking water, you should use only bottled water or water from a known safe source until you can have your water supply sampled, tested at a drinking water laboratory, and proven safe.

To obtain more information on water testing, please contact your local county environmental health sanitarian, or view our water testing web page located at the following website: www.iowadnr.gov/privatewelltesting.

OSHA has a fact sheet that highlights areas of safety concern associated with working in or near flooded areas. The information is available at the following website: https://www.osha.gov/OshDoc/floodCleanup.html.

The groundwater that supplies your water well can become contaminated through natural processes and human related activities. In addition, Iowa is made up of unique geological settings that can create special construction, maintenance, treatment, and water testing needs.

Even if you believe that your well water is safe to drink, it's important to periodically sample and test your water to assess any health related concerns the water may create. The information you receive from the test will help you make informed decisions on well maintenance and water treatment. It will also help you determine if you need to call a certified well contractor or seek an alternative source of drinking water.

Groundwater can have unsafe levels of natural pollutants such as, such as arsenic, lead and radon, and modern lifestyle related contaminants like motor fuels, the solvents and cleaners used to help clean clothing, homes and businesses, and chemicals that are beneficial for industrial and agricultural use. The degree to which a potential health threat may exist will depend on the amount and type of the contamination, the depth and protections incorporated in the well's construction, and how you use the water. In some cases, contamination of the water can be detected by sight, taste or smell; however, in most instances the contamination can only be detected through laboratory analysis of an untreated sample of the well water.

At a minimum, we recommend bacteria and nitrate testing be performed at least once per year. If you live in an area where nitrate is high, you should also test for nitrite. Arsenic testing should be done at least one time on each drinking water well, or more often if you are in an area where other wells exhibit a change in arsenic levels. Depending on the local geology and land use nearby your well, you may want to test for additional contaminants or test more frequently to look for high seasonal or an increase in overall contaminant levels.

Other reasons to schedule a well water test include:

  • When you hear about neighboring well owners who are having problems with their water quality,
  • You notice a change in your well water - things like changes in color, taste, odor, hardness, corrosion, sediment, and anything else unusual with the well water,
  • When you find that any of the contaminants you test for are close to the Maximum Contaminant Level (MCL) recommended by the Environmental Protection Agency (EPA) and you want to continue to consume the water,
  • Every time your well water system requires service work that shuts the well off and/or opens the water system up to outside air. This includes when you have your well serviced or the pump repaired, anytime you have work done on your pressure system - like replacing a pressure tank and/or pressure switch, fixing water line leaks, adding new water lines to your property, adding or repairing yard hydrants or livestock watering devices, adding or servicing water treatment equipment, and anytime a power outage lasts long enough for the water system to loose all pressure,
  • Anytime flood water has had access to the well site or inundated the top of the well, and
  • When the well has sat idle for a long period of time without being used - like when you go south for the winter, or the home sits empty for more than a few weeks.

You should test your water at least one time each year. Many well users choose to test their supply right before the holiday season because they know there will be guests consuming their water. Others pick a month during the year and make water testing one of the items that is on their yearly to-do list. What's important is that you make a plan to test your water supply. Water testing is easy and in many cases can be done at no cost to you.

Sometimes, a well user will test their water supply because they notice the water has changed in some way. Changes in water quality may indicate there may be a problem with the safety of the water supply.. The changes may be obvious like cloudiness, floating debris or sediment, and unusual odors and colors. They can also be subtle and difficult to notice. The subtle issues are difficult to distinguish and makes it hard to know if there is a problem because most of the time the water appears normal.

If there is any doubt that your water supply is safe to consume, we strongly recommend that you use an alternative known safe source for drinking water - like bottled water - until you have your water sampled and the testing provides proof that it's safe to drink.

In Iowa, wells are subjected to four distinct operational seasons - spring, summer, fall and winter. Each of the seasons can alter the manner in which you trouble-shoot well water quality problems. Although testing your well water can be done at any time of the year, some contaminants may be present only during specific conditions. Because of this, you should consider testing your water supply during times when the contaminants of concern are most likely to be present.

Coliform bacteria and nitrate are most likely to be found during wet weather, when runoff and excess soil moisture carry contaminants into shallow groundwater sources or through defects that may exist in your well's design, borehole or casing. In general, these are the wet periods of late spring and early summer as well as the wet periods of the fall.

Pesticides used on lawns, gardens, or farm fields are most likely to be present in greatest concentrations soon after they are applied. With the exception of large chemical spills, it takes excess soil moisture to carry pesticides into the ground which makes late spring and early summer good times to test for pesticides if they are one of your concerns.

For naturally occurring contaminants like arsenic, fluoride, and radium, testing can be done at anytime because these contaminants are relatively stable in the groundwater.

At a minimum, you should test your private drinking water supply for coliform bacterianitrate and nitrite, and manganese. These contaminants are the common indicators used to provide basic information on drinking water safety. It's easy and inexpensive to test for these contaminants. When any of them are present above the Environmental Protection Agency's maximum contaminant levels (MCL) or health advisory level, you should not drink or consume the water without proper treatment.

We also recommend that every private well have at least one arsenic test performed so that the well user understands if arsenic is an issue with the water supply. More information on arsenic can be found on the State Hygienic Laboratory Arsenic Fact Sheet.

You may want to test for pesticides and other farm related chemicals if you obtain your water from a shallow well or your well is old, or if you obtain your water from a well finished in the shallower Karst bedrock regions of the state.

Pesticides are mostly modern chemicals that are used to control weeds and insects, and improve crop and turf production. They are applied on farms and in communities. You likely have a number of pesticides that you use routinely in and around your home. Atrazine is one of the most commonly found pesticides discovered during well water analysis. You can learn more about Atrazine in drinking water and health concerns that may be attributed to this chemical by visiting the CDC Atrazine Information web page. For more information on specific pesticide well water testing you may want to consider, please contact the State Hygienic Laboratory at the University of Iowa, 800-421-4692.

There are a number of other contaminants that you may want to test for based on your location in the state, the location of the well, the aquifer supplying your water, the age of the well (based on construction standards), and the land use or land history nearby your well. Contaminants like nitrate, arsenic, fluoride, radium, and lead are naturally occurring in some aquifers and may require specialized water treatment to reduce or eliminate the exposure risk. Certain locations may be susceptible to contamination from things like Volatile Organic Compounds (VOCs) such as gasoline, plastics, adhesives, dry-cleaning fluids, refrigerants, paints and solvents; animal waste like manure, carcasses and compost, or a number of emerging contaminants that may be linked to our modern lifestyle and activities.

These contaminants can end up in the groundwater due to local use and application, improper mixing, handling and storage, improper disposal, accidental spills, poor well construction, improperly abandoned wells, or the lack of natural protections in the local geology that normally provide protection to the local aquifers. If the natural protective features and barriers are not present in your region, the aquifers are more susceptible to contamination and you should test your water more often.

In the northeast region of Iowa, Karst bedrock features can allow surface water immediate access to the shallow groundwater. This makes the shallow groundwater more susceptible to surface contaminants. Wells in this part of the state require more stringent standards for well construction, increased water quality monitoring and increased maintenance of any drinking water treatment devices needed. For additional information on Karst terrain and water wells, please view our water wells in Karst areas web page.

If your water supply lacks adequate protections, is in poor repair, or utilizes an aquifer that interacts with surface water or very shallow groundwater, you should be especially aware of water borne diseases. Bacteria, viruses and protozoa are microorganism groups that contain pathogens that can cause waterborne diseases. For additional information on water borne diseases please see the Centers for Disease Control, Iowa Department of Public Health or your local county environmental health office.

Some private water systems may have corrosion issues that create the potential to release lead from the home's plumbing into the water in the pipes. Corrosion in house plumbing can be described as a dissolving or wearing away of metal caused by a chemical reaction between water and your plumbing. There are a number of factors involved in the extent to which lead enters the water, these include:

  • the chemistry of the water (acidity and alkalinity) and the types and amounts of minerals in the water,
  • the amount of lead it comes into contact with,
  • the temperature of the water,
  • the amount of wear in the pipes,
  • how long the water stays in pipes, and
  • the presence of protective scales or coatings inside the plumbing materials.

We recommend that private water systems have at least one lead test performed to help determine if corrosion may be an issue with the plumbing. Additional testing may be required if you change your water source or your method of water treatment.

For advice on what your well should be tested for based on your well location and aquifer please contact your local county environmental health office, the State Hygienic Laboratory, the Iowa Department of Public Health or the Iowa DNR.

Nearly everyone who can follow instructions can draw a water sample and submit it for analysis. Since the water analysis normally looks for health indicator bacteria, it's important that the water sampling be performed with great care. Samples can be easily contaminated by the sample collector which will lead to a false indication that the water system is contaminated. If you are unsure about sampling procedures, call your local county environmental health office or your local Iowa Certified Well Contractor to obtain information on how you can have a water sample taken by experienced staff.

For additional information on how to correctly obtain a sample of your well water and submit it for testing, please refer to the State Hygienic Laboratory frequently asked questions web page.

Nearly all of Iowa's counties participate in the Grants-to-Counties Well Program. The Grants-to-Counties program can provide free water sampling and analysis to qualifying private drinking water systems. To find out if your county participates in the Grants-to-County Well Program or to arrange sampling of your water system, please refer to the list of County Environmental Health Sanitarians and contact the Sanitarian's office in the county where the well is located.

A professional lab technician analyzing a water sample

All water testing should be performed by Iowa DNR Certified Drinking Water Laboratories. These laboratories use accepted drinking water lab methods, employ highly trained staff who to perform the water analysis, and use DNR accepted standard operating procedures to help ensure your results are accurate.

To obtain additional information on well water testing or to order a water sample test kit, you can contact the State Hygienic Laboratory at the University of Iowa or any of the other Iowa DNR certified drinking water laboratory.

Each laboratory uses their own reporting form to detail the results of your drinking water analysis. Although the forms may look different, the information provided on each form should be nearly identical. When testing for coliform bacteria and nitrates, most lab analysis forms will state whether the water supply is "safe" or "unsafe" to use as a drinking water supply and state what the level of nitrate they found. You can also request that the laboratories provide you with a numerical level for the bacteria found in the sample if you make this request at the time the water sample is submitted and include the additional fee.

The goal of drinking water testing is to inform the well user if the water supply is safe for all consumptive uses. Testing "safe" means that the water supply is "absent" of coliform bacteria and fecal coliform bacteria, and the nitrate level is 10 mg/L or less when measured as nitrate-nitrogen or NO 3- N, or 45 mg/L or less when measured as Nitrate, Total Nitrate or NO3, and you have no reason to believe that there are other contamination concerns with the water supply. If you test for Nitrite, the result should be less than 1 mg/L.

When you have your water tested for other types of contaminants, the Environmental Protection Agency (EPA) maximum contaminant levels and guidelines should be used to determine if your water is safe to drink. The Water Systems Council wellcare® water testing information page offers additional guidance on well water testing and understanding your water analysis report.

The State Hygienic Laboratory at the University of Iowa is also a great resource and offers a number of documents for private wells. "Reading your water analysis report" is a document that can help you understand how to interpret private drinking water analysis reports based on their testing services.

First and most important - stop consuming the water and find an alternative source for all of your consumable water needs. This can be bottled water, a neighboring water supply that is known safe, water from a public water supply like a neighboring town or city, or water that has been properly treated for the contaminants present in the water.

Then you should determine what the best short term and long term solutions are for your safe drinking water needs. Your options are to use bottled water for all consumable water needs, providing adequate water treatment at one or more drinking water taps, rehabilitation or renovation of the well or water system so that it provides safe water, connection to a known safe water supply, or replacement of your existing water supply.

In some cases, the issues that can cause drinking water contamination are simple and can be remedied by adding protections to the existing well, or a simple point of use water treatment system. Other times, the only effective solution will be an alternative source of water. 

You should discuss the water quality issues with a Iowa DNR Certified Well Contractor. They can help diagnose your water issues and provide guidance on repairs or well replacement. Anytime you hire a contractor to work on your well or water system, the contractor must be certified by the Iowa DNR in the proper categories of well services.

Certification ensures that the individual you hire meets a minimum level of knowledge and skill in the areas needed for your job. It's important to note that you should select your contractor carefully because even though a contractor may be certified by the state, they may not have the equipment or the experience to perform all well services.

To obtain additional information on water system rehabilitation, renovation, repair or replacement, please contact your local Iowa DNR Certified Well Driller or Certified Pump Installer.

To learn more about ownership of a private water supply, please look at our private well consumer information booklet.

Water treatment devices are commonly used to produce safe drinking water. The type of device you need and the installation, maintenance, and monitoring of your treatment device will depend on the type of contamination that you have and the type of device you choose for treatment. Some contaminants require very specialized water treatment. Even if you already have some form of water treatment, you may not be reducing or removing all contaminants that can cause short or long term health issues.

One last important point to consider is that all water treatment devices require ongoing maintenance, monitoring, and testing to ensure that they are properly treating the water. The maintenance intervals and cost of maintenance vary with each specific treatment device. Make sure to inquire about ongoing maintenance schedules and the true cost of ownership when you discuss your water treatment options.

All drinking water treatment devices that are sold in Iowa must undergo third-party testing and be registered under a program administered by the Iowa Department of Public Health (IDPH). For additional information on water treatment system registration, please contact the IDPH at their home drinking water treatment system registration web page.

To learn more about water treatment device options, please look at the information on the following links:

For more information:

Russell Tell, Environmental Specialist Senior
Wallace State Office Building
502 E. 9th Street
Des Moines, IA 50319-0034
(515) 725-0462 or by Fax: (515) 725-8202
russell.tell@dnr.iowa.gov