Drinking Water Quality in Iowa

There are two main sources of drinking water in Iowa: public water supplies and private wells. 

Public water supplies include city water utilities, rural water supplies, mobile home parks and other systems that regularly serve 25 or more individuals. These systems are regulated to maintain specific water quality standards. 

Private wells can generally be thought of as drinking water sources that serve fewer than 25 individuals per day. It is the responsibility of private well owners to maintain the well’s water quality, including annual testing for pollutants.


Public Water Resources

The Iowa Department of Natural Resources (IDNR) is responsible for ensuring the safety of public drinking water sources by monitoring water quality on a routine basis, ensuring that public water systems are designed, operated and maintained to minimize the possibility of contamination, and by notifying the public in the event of a violation.

The IDNR compiles an annual report, The Iowa Drinking Water Program Annual Compliance Report, on violations to drinking water quality standards. The report can be found here: https://www.iowadnr.gov/Environmental-Protection/Water-Quality/Water-Sup...

In 2021, 2.94 million Iowans were served by public water supplies and the IDNR recorded 1,842 public water supply systems. The percentage of systems in compliance with all health-based standards in 2021 was 96.2%. There were 70 public water supplies that had 107 violations of a health-based drinking water standards, maximum residual disinfectant level, treatment technique, or action level. A breakdown of the 2021 violations are included below. The most common violation of health-based drinking water standards were for nitrate-nitrogen followed by arsenic. Appendix B-2 of the report includes the lists of violating public water systems. 

2021 Health-Based Standard Violations by Iowa Utilities2021 Percentages of Health-based Standard Violations by Iowa Utilities


Private Wells

Private wells can generally be thought of as drinking water sources that serve fewer than 25 individuals per day. About 7% of Iowans, or 230,000 individuals, rely on private wells. It is the responsibility of private well owners to maintain the well’s water quality, including annual testing for pollutants.

Why should I test my well annually? 

There are many reasons to test your well! It all boils down to knowing what you are drinking. Here’s a couple:  

  • Testing your water annually will help keep you, your family, pets, livestock & others safe. 
  • Some pollutants are odorless and tasteless and will not be removed by boiling water. 
  • Pollutants like bacteria, arsenic and nitrate are found at elevated levels in 10-30% of private wells in Iowa. (Source: Iowa Department of Public Health) 
  • Iowa has a unique program that allows for free or low-cost annual testing of private wells. 

Understanding your well’s water quality 

There are many different factors that contribute to the quality of your well’s water such as well construction, geographic setting and land use in your watershed. Wells that were constructed before 1982 often have fewer protective construction features and well owners may lack documentation about the construction.  

It’s also important to remember that no matter when or how your well was constructed, well water quality can change over time. The best way to make sure that your well water is safe is to test annually. 

Testing your well 

All counties in Iowa participate in a program called Grants-to-Counties that allows for free or low cost annual testing for private wells. In order to access the program, contact your county department of environmental health and they will send a county employee to take your sample for you.  

These county employees are called Environmental Health Specialists or Sanitarians, and are a knowledgeable resource for private well owners. Sanitarians are trained to take an accurate water sample and to help you interpret your results. You can find the contact information for your county sanitarian on this spreadsheet which is updated frequently by the Department of Natural Resources: https://docs.google.com/spreadsheets/d/e/2PACX-1vSN9_vM3stj69X3-4qojMfxrkIGuP4dkCfZYo1DI9g8FSyJrs4SbfRYuDRPulMxStPClHPxdB1io1GR/pubhtml 

If your sanitarian is not able to take a water sample, or you would prefer to take the sample yourself, the State Hygienic Lab offers testing kits that can be mailed to your home. There is a fee for this test, between $15 - $18 per contaminant.  

What should you test your well for? 

  • The best way to understand what you should test for is to talk with your sanitarian. They have a good understanding of local water quality issues.​ 
  • At a minimum, test yearly for nitrate and bacteria​ 
  • Test every 6-10 years for arsenic​ 
  • If you notice a change in the appearance, taste or smell of your water, talk with your sanitarian to discuss additional testing. 


Bacteria are usually broken down into three forms: total coliform, fecal coliform and E. coli. Total coliforms, the most generic type of bacteria, can be found in plant material, the soil, and the digestive tracks and waste of animals including humans. The presence of total coliform bacteria in drinking water indicates a sanitary defect; that a pathway exists for soil and/or sewage to enter the system. This pathway represents a potential health hazard because there is an opportunity for harmful material to enter the drinking water.

Fecal coliform, a type of total coliforms, is more specifically derived from the guts and feces of warm-blooded animals. E. coli, a type of fecal coliforms, indicate fecal pollution and the possible presence of pathogens. The presence of fecal coliform/E.coli in drinking water indicates a pathway exists from a relatively fresh waste/sewage source. This pathway represents a serious health concern because the water may be contaminated with enteric microorganisms that can cause disease.

The Grants to Counties Program will usually test for total or fecal coliforms, and if a problem is detected they may recommend testing for E. coli. Total coliforms are generally harmless, but E. coli can cause short term health effects like nausea and headaches.​

Private well owners should test for bacteria every year. A safe well should have no detectable bacteria. If bacteria are found it may mean that there is something structurally wrong with the well such as a well cap that is not watertight. Work with your sanitarian or a private well contractor to inspect the well and recommend treatment.​ After the structural problem has been remedied you will need to shock chlorinate your well. 


Nitrate, the water solvable form of nitrogen, is odorless and tasteless. Nitrate can come from agricultural land, septic systems, feedlots and other sources. The maximum contaminant level, or the level at which the water is still safe to drink, is 10 mg/L. Nitrate tends to be a problem in shallower wells that are less than 100 feet or in areas that have karst geology. Ingesting water with high nitrates has been linked to negative health effects such as methemoglobinemia or “blue baby syndrome” in infants which reduces the capacity of the blood to carry oxygen, birth defects, thyroid disease, and colon cancer.​ (Ward, M., R. Jones, J. Brender, T. de Kok, P. Weyer, B. Nolan, C. Villanueva , S. van Breda. “Drinking Water Nitrate and Human Health: An Updated Review. International Journal of Environmental Research and Public Health 15(7):1557. July 23,2018. https://doi.org/10.3390/ijerph15071557

Nitrate can be removed through some home treatment systems such as reverse osmosis, distillation and anion exchange. 


Arsenic, which is odorless and tasteless, occurs naturally in rocks and soil. It is also a byproduct of agriculture and industry including copper smelting, mining and coal burning.​ Studies have shown that repeated ingestion of water with arsenic over a person's lifetime is associated with increased risk of cancer as well as diabetes, cardiovascular, immunological and neurological disorders.​ 

The maximum contaminant level, or the level at which the water is still safe to drink, is 0.01 mg/L. The Iowa Department of Natural Resources recommends that wells be tested for arsenic every 6 to 10 years. If your test is elevated, you may need to more routinely test. 

Arsenic can be removed through some home treatment systems: reverse osmosis, distillation, activate alumina, and anionic resin.​ 

Well Assessment 

Your well should be inspected every 5 years by a licensed well contractor. The inspection should include the pump, storage tank, pipes and valves, and water flow.​ When hiring a contractor for any well services, make sure they are properly certified by the Iowa Department of Natural Resources. You can find a map of private well contractors here: https://wellowner.org/find-a-contractor/iowa/. And you can check to make sure that your contractor is certified through the DNR here: https://programs.iowadnr.gov/opcertweb/pages/oper_search.aspx​. You should always have a contract when hiring anyone for well services.​ 

The Grants to Counties Program also has funding to help pay for well assessments, shock chlorination, well renovation and/or rehabilitation, well plugging, and cistern plugging. Reach out to your county sanitarian to understand what funds are available.  

Filter or Home Treatment System 

The best resource on choosing a home treatment system is through the State Hygienic Lab: http://www.shl.uiowa.edu/env/privatewell/homewater.pdf​. This helpful guide takes you through the various possible contaminants and which home treatment systems can help. 

Would you like to learn more about protecting your well’s water quality?

The Private Well Stewardship Program is an educational program offered through Iowa State University Extension and Outreach in which
private well owners learn about the responsibilities and risks of being a private well owner and are connected to additional resources to manage their well.

This program is designed for busy Iowans, consisting of two one-hour sessions, with the goal of assisting you in safeguarding your drinking water.

Contact your county ISU Extension and Outreach office and ask if they are offering the Private Well Stewardship Program in your area. Or, you can contact Catherine DeLong (crdelong@iastate.edu, 515-294-5963), water quality program manager at ISU Extension and Outreach, who leads the program.