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Extension > Environment > Water Resources > Property owners > Shoreland maintenance > Accessing information to protect water quality

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Ensuring a safe water supply

A safe water supply

When clear, good-tasting water comes out of the faucet, we assume it is safe to drink. Unfortunately this assumption is not always correct. Most shoreland properties have a private water supply that needs to be tested regularly to confirm water is safe to drink and use.

At seasonal or vacation homes it is important to test water every year if the well is not used continuously. Residences near lakes and rivers often have wells that use shallow ground water. Seasonal homes or cottages may have older wells that need repair or replacement, but are a lower priority than the primary residence. Older, shallow wells are at the most risk from ground water contamination, so the water from these wells needs to be tested annually.

Many vacation dwellings use surface water for the household water supply. Surface water presents a different set of risks and problems. Information about special consideration and testing for surface water is available from the Minnesota Department of Health (MDH).

The most obvious concern about an unsafe water supply is the health risk to family or guests. Wastewater contamination serves as a source of bacteria, viruses, and parasites that can cause gastrointestinal problems or transmit contagious diseases. High levels of nitrate from fertilizer or wastewater can present a serious health risk, and poisons resulting from improper use or disposal of chemicals can cause long-term or chronic health problems for humans or animals.

Another reason to make sure your shoreland property has a safe water supply relates to property value and transfer. A safe water supply is an essential component of a valuable piece of shoreland property. Also, at the time of property transfer, most lending institutions will not provide financing for the purchase of a property without a safe supply. They generally require a water test on a sample collected by a third party within 60 days of closing.

Is there a problem?

The following may indicate there is a problem with the quality of your water, and that you should have the water tested to ensure that it is safe:

Problem wells

Sandpoint or drivepoint wells are common near shorelines, taking advantage of the high water table that may occur near lakes or rivers. They consist of a screen on the end of a pointed pipe that is pounded, or driven, down to the water table. Because surface and ground water are directly connected in shoreland areas, shallow wells may be essentially drawing water from the lake itself.

Many shallow hand-dug wells still exist in rural areas. Dug wells may be cased with tile or culvert and are especially susceptible to contamination.

Water wells that are no longer in use must be properly sealed to prevent contamination from seeping into ground water. Any unused or abandoned well can present a serious safety hazard for children or pets, as well as a direct route for contaminants to reach ground water.

Using surface water

The Minnesota Department of Health does not recommend using surface water as a drinking water supply. If you decide to use surface water for drinking at your shoreland property, contact MDH or your county health department for guidelines on how to treat it to ensure a safe supply.

Because water from lakes and rivers contains bacteria and other living organisms, it must be disinfected before being used as drinking water. Water can be disinfected with chemicals (chlorine, bromine, iodine), by boiling or with ultraviolet light. Filtration alone will not provide safe drinking water because it does not kill the bacteria, viruses or parasites that can cause disease.

Giardia are parasites present in most of Minnesota's surface water today and can cause giardiasis, an intestinal disorder. The parasites are very small and will pass through filter membranes unless they are extremely fine.

When to test

Private water supplies should be tested regularly. The MDH requires a well test immediately after construction. After that, recommended test frequency depends on well location, construction, and on previous test results. Testing every two to three years may be sufficient for wells that have no history of contamination, are isolated from pollution sources, and have 50 feet of watertight casing.

Shallow wells, wells that have shown contamination, or wells without a watertight casing (such as dug wells) should be tested at least once a year. Testing should be done when the well is most susceptible to contamination, usually immediately after spring thaw or heavy rainfall.

The water should also be tested:

What to test for

Water quality may be affected by:

Primary contaminants--Chemicals and organisms that may cause acute disease or long-term health effects; coliform bacteria and nitrate are examples of primary contaminants.

Secondary contaminants--Cause objectionable odors, tastes, staining, corrosion, or other aesthetic problems that do not generally pose a health risk; secondary contaminants are usually naturally occurring minerals (such as iron) or organisms (such as soil bacteria).

Municipal water supplies must be tested for over 80 primary drinking water standards. It would be prohibitively expensive to do all these tests on private wells, so they are usually tested for coliform bacteria and nitrate. Coliform bacteria and nitrate are used as indicators of water contamination. Bacteria may come from septic systems or animal feedlots and nitrate may indicate contamination from wastewater or fertilizer.

Be sure to have your water tested at a certified lab. For accurate results, water samples should be tested within 24 hours of collection. For more information on how to collect a water sample or on drinking water standards, contact a regional office of the MDH, your community health service, or your county Extension office.

Best practices for safe water supplies

To maintain a safe water supply, follow these guidelines:

Regulations that apply

In Minnesota, there are certain regulations and recommendations to guarantee a safe water supply:


Testing for nitrate and coliform bacteria usually affordable. Some communities offer free water testing or low-cost screening for residents.

Drilling a new well can be expensive. However, constructing a new well will increase property value and may be necessary for future property transfer if water from the existing well is unsafe. The health and safety of family and guests should outweigh the financial costs of ensuring a safe water supply.

For more information

Shoreland Best Management Practices

Reviewed 2017

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