Fortunately, most Minnesotans probably don’t have to worry about this question when drawing a glass of water. We generally take drinking water safety for granted.

If your drinking water is provided by a public system, the provider — usually the municipality — is responsible for ensuring that the water is safe. However, about 20% of Minnesotans get their drinking water from private wells. If you are one of them, you are responsible for making sure your family’s water is safe to drink.

The Minnesota Department of Health has available a wealth of information to assist well owners and offers the following TIPS: Test your water, inspect your well, protect your well and seal unused wells. Well location, construction and maintenance go a long way in ensuring the safety of your drinking water. Many wells that do not meet health standards for nitrate or bacteria fail one or more of these tests.

There are several pollutants that can impact drinking water quality. Some are just nuisance factors, like iron or manganese, which can affect the odor and taste of water. Others are very site-specific, like the perfluorochemicals (PFCs) affecting the east metro area. There are four primary factors for which the MDH recommends well testing: arsenic, lead, bacteria and nitrate.

One-time testing recommendations
The MDH recommends that well owners test their water for arsenic at least once. The MDH reports that natural arsenic concentrations exceeding drinking water standards occur in about 10% of wells in Minnesota. Arsenic treatment methods include reverse osmosis and distillation. Other options include drilling a new well — though this may not solve the problem if arsenic levels are high throughout the area — or using bottled water.

Lead is usually not detected in well water in Minnesota. However, household plumbing components may contain lead, which can dissolve and contaminate water supplies regardless of water source. The MDH also recommends that well owners test their water for lead at least once.

Because the source of the lead may be in your home, rather than in your well, solutions are different. Health experts recommend letting the water run for at least 30 seconds before using it for drinking or cooking to flush out the water that has been standing in the pipes. Using cold water is also recommended, as hot water dissolves lead from pipes and fixtures faster than cold water.

Annual, biennial testing recommendations
The MDH recommends that well owners test their water for coliform bacteria every year and nitrate every other year. These two contaminants often occur together and can be an indication of poor well location, construction or maintenance. A great deal of attention has been focused on nitrates, in large part due to the Minnesota Department of Agriculture’s Nitrogen Fertilizer Management Plan and associated rule development. The MDA reports that of the more than 20,000 private wells tested from 2013 through 2017, more than 90% meet the drinking water standard for nitrate of 10 mg/liter. It is also worth noting that these wells were in areas of the state identified as the most vulnerable to contamination. The MDH reports that about 96% of new wells have nitrate concentrations below 3 mg/liter.

Nitrate and bacteria often occur together, and there is ample evidence implicating both in human health effects often associated with nitrate. The MDA recommends a follow-up test for bacteria if nitrate levels exceed 5 mg/liter, and annual tests for both nitrate and bacteria to ensure water safety in these situations.

Bacteria can be removed by boiling or chlorination. Reverse osmosis systems are often used to remove nitrate. Boiling does not remove nitrate, and it can actually increase the concentration due to evaporation. Infants under 6 months of age should not be given water that does not meet the nitrate standard, which was specifically developed to be protective of infants. Most adults can consume large amounts of nitrate with no ill effects.

If you would like more information on well management, visit the MDH Owner's Guide to Wells webpage.

Formo is executive director of the Minnesota Agricultural Water Resource Center.