Maintaining Safe Drinking Water in Your Private Well

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Jamie Benning
Water Quality Program Manager
Iowa State University Extension and Outreach


Many rural residents in Iowa rely on private wells as their source of water for drinking, cooking, washing clothes, and watering livestock.  Even if your well and the area around it have remained unchanged, it is important to test water annually for indicators of contamination, including nitrate and bacteria, to ensure the water is safe to drink.  The spring and early summer months are an ideal time to test as melting snow and spring rains move through the soil and recharge groundwater sources.  Changes in color, taste, and odor are also indicators that a test should be taken to ensure the health and safety of water for drinking and other uses. 

Testing well water

Drinking waterThe Iowa Department of Public Health administers a program for private well water testing.  Water testing kits can be ordered through your local county environmental health department or county sanitarian.  Many counties participate in the Grants-to-Counties Well Program that provides financial assistance for water testing.  Testing kits may also be ordered through the Iowa State Hygienic Laboratory Private Well Water section.  For more information about testing for specific contaminants, visit the Iowa Department of Natural Resources Private Well Testing website. 

Well Water Safety after Flooding

If flood waters reached your private well casing, covered the top of the well casing, or covered areas around neighboring wells, Iowa DNR recommends testing for total coliform bacteria.  If a well tests positive for bacteria, an alternative water source should be used for cooking and drinking until a test indicates that it is safe.  The contaminated well should be purged, shock chlorinated, and tested until two consecutive tests indicate the water is free of bacteria. Flood waters also have the potential to carry nitrate into groundwater sources.  If the initial test post flooding is near 10 mg/L or above for nitrate as nitrogen, testing every 6 months is recommended. Water with a nitrate concentration of 10 mg/L or higher should not be consumed by infants under 6 months of age or pregnant women. For more information about well testing and maintenance following a flood event, read Iowa DNR publicationWhat should I do when my well floods.”

Protecting well water

While some groundwater contaminants are naturally occurring in certain aquifers, other contaminants, including nitrate, petroleum products, and bacteria, are influenced by management of the area around the well and within the well capture zone.   Maintaining minimum separation distances between the well and common sources of nitrate, bacteria, and other contaminants are recommended to minimize well water contamination and maintain well water quality.  Separation distances for common acreage and farm contaminant sources can be found in ISU Extension publication PM0840, Good Wells for Safe Water

Source water protection

Managing contaminants not only benefits the private well owner, but also minimizes the impact of common contaminants on neighboring wells, local community source water supplies and surface water.  Groundwater recharges rivers and streams, transporting any contaminants that are not filtered by the soil into surface water.  Following best management practices and recommendations including applying nitrogen fertilizer at Iowa State University recommended rates, proper use and disposal of chemicals, and closure of unused wells will protect drinking water of private well owners and source water for nearby communities. 

Private well protection resources

Iowa’s Private Water Well Program
Good Wells for Safe Water (PM 840)
Shock Chlorinating Small Water Systems (PM 899)
Sampling Your Drinking Water (PM 1335)
Well Water Quality and Home Treatment Systems

Date of Publication: 
July, 2019