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Do you have questions about testing the water quality of the private drinking water system that you use?
This page offers answers to a number of common questions we receive about testing the water obtained from private wells and water systems.
- Choose a topic -
- Overview
- Why should I test my water supply?
- How often should I test my water supply?
- When is a good time to test my water supply?
- What should I test for?
- Who can perform the water sampling?
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What should I test for?
Private drinking water analysis usually looks for common water drinking quality indicators whose presence may mean that the well and water system is not safe to drink.
At a minimum, you should test your private drinking water supply for coliform bacteria and nitrates. These contaminants are the two most common indicators used to provide basic information on drinking water safety. It is easy and inexpensive to test for these contaminants and their presence above the set maximum contaminant levels (MCL) indicates that you should not be drinking the water without proper treatment or water system repairs or replacement.
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 (construction standards), and the land use or land history nearby your well. Contaminants like arsenic, fluoride, radium, and lead are naturally occurring in some aquifers and may require 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 and paints; pesticides, which include a large group of compounds used to control animal and plant infestations; animal waste; and in some cases other emerging contaminants.
These contaminants can end up in the groundwater due to local use and application, improper handling or storage, improper disposal, accidental spills, improperly abandoned wells, or lack of natural protections in the local geology that leaves the aquifer(s) susceptible to contamination.
In the northeast region of Iowa Karst bedrock features can make shallow groundwater more susceptible to surface contaminants. Water supplies in this part of the state require additional considerations for well construction, water treatment and monitoring. For additional information on Karst terrain please view our Water Supply Wells 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 containing pathogens that can cause waterborne diseases. If you believe that your drinking water has made you ill, you should obtain your drinking water from only a known safe water source and contact a physician's office immediately to discuss your symptoms. Your water supply should also be sampled and tested for the appropriate microorganisms. 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.
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.
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Who can perform the water sampling?
The well owner, the well users or their agents, or any number of health and environmental health specialists can obtain a water sample from your water system for testing. Since the water analysis will normally be looking for health indicator bacteria, it is important that the water sampling be performed with great care so that the sample is not accidently contaminated - leading to a false indication that the water system is contaminated. If you are unsure about sampling technique, call your local county environmental health office to obtain information on how you can have a water sample taken by experienced county staff.
For additional information on how to correctly obtain a water sample for testing, please refer to theState Hygienic Laboratory private well sampling State Hygienic Laboratory private well sampling information sheet.
Most of Iowa's counties participate in the Grants-to-Counties Well Program. The Grants-to-Counties program will 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.
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Can any lab perform the water analysis?
For water testing paid for under the Grants-to-Counties Well Program or for the required water testing for new well construction or well repair, the Iowa DNR requires that the water testing laboratory be certified by the Iowa DNR for drinking water analysis. Iowa DNR Certified laboratories use accepted lab methods, employ staff who are qualified to perform the water analysis, and use DNR accepted standard operating procedures to help ensure accurate test results.
To obtain additional information on well water testing or to order a water sample test kit, please contact the State Hygienic Laboratory at the University of Iowa or any of the other Iowa DNR certified drinking water laboratories.
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How do I interpret the laboratory report?
Each laboratory uses their own reporting form to inform you of the results of your drinking water analysis. Although the forms may look different, the information provided on each form should be nearly identical. 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. Most drinking water laboratories will also provide you with a numerical level for the bacteria found for an extra fee. The goals for drinking water testing are that the water supply test "safe" for drinking water use. Testing "safe" means that the water supply is "absent" of coliform bacteria and fecal coliform bacteria, and the nitrate level is 10mg/L or less when measured as nitrate-nitrogen or NO3- N, or 45 mg/L or less when measured as Nitrate, Total Nitrate, or NO3.
If you requested any additional testing for other types of contaminants, the maximum levels of each contaminant should be less than the maximum contamination levels set for drinking water as determined by the Environmental Protection Agency.
The Water Systems Council wellcare® water testing information page offers additional guidance on understanding your water analysis report.
The State Hygienic Laboratory at the University of Iowa offers a web page that can help you understand how to interpret private drinking water analysis reports based on their testing services. Reading your water analysis report
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What should I do if my water supply is unsafe to drink?
If you have determined that your water supply is unsafe to drink or you are concerned that your water supply is unsafe to drink, the first thing that you should do is find an alternative source of drinking water. 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. You should then determine what the best short term and long term solutions are for your water needs. Your options are to continue the use of bottled water for all drinking water purposes, providing adequate water treatment at each drinking water tap, rehabilitation or renovation of the well or water system so that it provides safe drinking water, connection to a known safe water supply, or replacement of your existing water supply. You should have the well inspected to ensure that your water system includes the protections needed to make it a safe drinking water supply. Anytime you hire a contractor to work on your water system, the contractor must be certified by the Iowa DNR the proper categories of well services. Certification ensure that you hire an individual who has the knowledge and skills needed to solve your drinking water issue.
To obtain additional information on water system rehabilitation, renovation, repair or replacement, please contact your local Iowa DNR Certified Well Contractor.
To learn more about ownership of a private water supply, please look at our private well consumer information booklet.
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Can I use a water treatment device?
Water treatment devices are commonly used to create safe drinking water. What type of device that 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 used for treatment. Some contaminants require very specialized water treatment so even if you already have some form of water treatment already, you may not be reducing or removing all contaminants that may cause health issues.
One last important consideration is that all water treatment devices require maintenance, monitoring and testing to ensure that they are properly treating the water. The maintenance intervals and cost vary with each specific treatment device. Make sure to inquire about ongoing maintenance cost when you discuss your water treatment options.
All water treatment devices that are sold in Iowa must be registered under a program administered by the Iowa Department of Public Health. For additional information on water treatment system registration, please contact the IDPH at their water treatment system registration web page.
To learn more about water treatment device options, please look at the information on the following links:
State Hygienic Laboratory at the University of Iowa information booklet "Well Water Quality and Home Treatment Systems."
National Sanitation Association's Home Water Treatment Devices guidance web page.
Water Systems Council Home Drinking Water Treatment Systems web page.
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Additional Resources
Iowa DNR Information about Arsenic in Iowa's Drinking Water
Frequently Asked Questions from the State Hygienic Laboratory at the University of Iowa
Reasons to test your water - an EPA web page
Drinking Water from Household Wells - an EPA publication
Do you have questions about your well? informational brochure by the Water Systems Council
Renting a Home with a Private Well
Water Systems Council wellcare® information series for private well owners and users
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- For additional information contact -
Russell Tell, Environmental Specialist Senior
401 SW 7th St, Suite M
Des Moines, IA 50309-4611
(515) 725-0462 or by Fax: (515) 725-0348
russell.tell@dnr.iowa.gov
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