Quick facts
- Groundwater is the drinking water source for approximately 75% of Minnesotans.
- Water is supplied from public water systems or private wells.
- You should test your private well regularly for certain contaminants.
- Public water suppliers are required to meet drinking water health and safety standards and ensure adequate supply to their connections.
The majority of drinking water in Minnesota comes from groundwater. This water is stored in underground aquifers, which is then pumped to the surface for our consumption.
Depending on where you live, you can get your drinking water from either a public water utility or a private well.
Public water supply
Homeowners that are connected to a public water utility get their water pumped to their house from a local water supply. If you receive a water bill each month, this probably includes you.
Community public water suppliers serve at least 25 persons or 15 service connections year-round. Most cities and towns fall into this category.
Public water suppliers are required under the Safe Drinking Water Act to meet drinking water health and safety standards as well as ensure adequate supply to their connections. Your public water supplier is required to test for contaminants regularly and they need to be within the health risk limits before they can issue you water.
If you have an older home, testing for lead may be a good idea, since lead in drinking water usually comes from older plumbing in the home and not the water supply.
If you’re interested in your water supplier’s testing results and water quality you can search for their annual report on the Minnesota Department of Health site.
Private water supply
Homeowners or renters that get their water from a private well are more likely to live in rural areas and have some sort of well on their property. If you use well water, you should not receive a bill from a water supplier. Since you own the property you also own your well.
Water from a private well is plumbed into your home and sent to your faucets, toilets and showers through a pressure tank. “Tap water” is a common term used for well water that comes out of your sink, and that is most commonly used for cooking and drinking.
The pros and cons of owning a private well
Some of the benefits are not having to pay a monthly bill to a water supplier, you know exactly where the water comes from, and after a water test, you’ll know what and if any chemicals and minerals are in the water.
Some cons to a private well are the upkeep and cost if something happens to the well (a new well can cost several thousands of dollars), maintaining pumps and plumbing, and the testing that goes along with having safe drinking water.
As a well owner, you are responsible for making sure your water is safe to drink. In Minnesota, there are no regulations that make you test your drinking water. And if you do find a problem, it is up to you to either fix it or find a different water source.
Under certain circumstances, if there is a disruption in your water supply or quality, you may be able to get help fixing the problem from a government agency, usually through grant funding.
Some options for treatment if you find an issue with your drinking water:
- Installing a treatment system (for example, a reverse osmosis system).
- Identifying above-ground contamination and removing it.
- Drilling a new well.
- Updating plumbing to your drinking water source.
These treatments can range in cost depending on where you live and what the issue is. The Minnesota Department of Health has a list of water treatment options.
When testing your well water for contaminants it is important to use a source of water most often used for drinking, usually the water out of your kitchen faucet or bathroom. It is important to use a certified water testing lab when getting a water sample.
This list of Minnesota groundwater testing labs includes laboratories from across the state. These laboratories will give you specific instructions on collecting water for your test and possibly a sample kit. It is important to follow the instructions so you don't contaminate your results.
Drinking-water contaminants
Listed in alphabetical order, not in order of importance or recommendation.
Arsenic is a naturally occurring element in rocks and soil. It is prevalent in certain parts of Minnesota and can dissolve into groundwater.
Drinking water that contains arsenic can increase the risk of serious health effects, including bladder, lung and liver cancer, and diabetes. There is no way to know whether arsenic will be present in groundwater before drilling a well but there are parts of Minnesota where arsenic is shown to be more present.
You cannot see, taste or smell arsenic in water.
- EPA standard: 10 micrograms per liter
- Testing: It is recommended to test your well at least once for arsenic.
- If arsenic was NOT detected in the first sample, it is unlikely to have arsenic later.
- If arsenic is detected, you may want to retest it about six months after construction to verify the levels.
- Treatment options and guidance:
- Adsorptive media filtration
- Aeration and filtration
- Alternate water supply
- Anion exchange
- Continuous chlorination and filtration
- Distillation
- Oxidizing media filtration
- Ozonation and filtration
- Reverse osmosis
Current testing results on Arsenic in Minnesota can be found through the Minnesota Department of Health.
Coliform bacteria pose little health risk and are not usually found in groundwater. But you should test for them every year because they can be an indicator of a breach, failure, or other change to the well system.
Coliform bacteria are found in large numbers in the feces of warm-blooded animals. When found, this could indicate a sewage leak into the well supply.
Once Coliform bacteria are found in a water test you should test for other contaminants such as E. Coli to narrow down the source of the bacteria and reduce the problem.
- EPA action level: Any amount of coliform bacteria detected
- Testing: Once a year
- Treatment options and guidance:
- Alternative water source
- Continuous chlorination and filtration
- Distillation
- Ozonation and filtration
- Remove the source of contamination
- Reverse osmosis
- Ultraviolet (UV) disinfection
Lead is a poisonous metal that can cause long-term health and behavioral problems.
Lead occurs naturally and was used in the past for many construction projects. Normally, lead is not present in groundwater. The main source of lead is from older plumbing in homes, usually installed before 1986. As water runs from the well into the home and through the plumbing, lead can dissolve into the water.
The only way to know how much lead is in your drinking water is to test it.
- EPA action level: 15 parts per billion for 10% of water samples. There is no safe amount of lead in drinking water.
- Testing: At least once.
- Treatment options and guidance:
- Alternative water source
- Carbon filter
- Distillation
- Reverse osmosis
- Let the water run for 3 to 5 minutes before using it for cooking or drinking. Use cold water.
Manganese naturally occurs in rocks and soil and can dissolve into water. Typically, groundwater in Minnesota has lower levels of manganese in the southeast and higher levels in the southwest. There is no clear pattern in other parts of the state.
Manganese is an important nutrient for health and adults need about 1,900 to 2,600 micrograms per day. Usually, adults are able to get this from the food we eat.
However, infants need 600 micrograms per day or less. Consuming too much manganese over time can cause problems with memory, attention span and motor skills. Infants under the age of one may develop learning and behavior problems.
- EPA Action Level:
- If you have an infant under the age of one that is drinking the water or drinks formula made from tap water, a safe level is 100 micrograms or less of manganese.
- If you have an infant under the age of one that does not drink the tap water or formula made from tap water, a safe level is 300 micrograms or less.
- If no one in your household is under the age of one, a safe level is 300 micrograms or less.
- Testing: At least once and before an infant under the age of one drinks the water.
- Treatment options and guidance:
- Aeration and filtration
- Carbon filter
- Continuous chlorination and filtration
- Distillation
- Oxidizing media filtration
- Ozonation and filtration
- Reverse osmosis
- Water softening
Nitrates can be found in groundwater, surface water and soil. Consuming too much nitrate is particularly dangerous to infants by affecting oxygen in their blood causing methemoglobinemia, also known as Blue Baby Syndrome. Infants who are bottle-fed under the age of six months are at the highest risk.
Nitrate (NO3-) is a naturally occurring compound found in nature but levels in groundwater can increase due to man-made fertilizers applied to farmland, as well as other sources, such as industrial pollution, stormwater and wastewater.
The Minnesota Department of Agriculture is taking action to reduce the risk of nitrate contamination in drinking water in relation to agricultural activities, by implementing drinking water testing and the University of Minnesota’s recommended Best Management Practices.
- EPA Standard: 10 parts per million
- Testing: You should test your drinking water for a level of nitrate every other year, or if you are pregnant, planning to become pregnant, or if infants will be drinking your water.
- Treatment options and guidance:
- Alternate water supply
- Anion exchange
- Distillation
- Reverse osmosis
Download this map showing the concentration of drinking water wells within a township with elevated nitrate levels in Minnesota. Source: Minnesota Department of Agriculture
PFAS are manmade chemicals that are extremely stable and do not break down in the environment. Common uses of PFAS include:
- Nonstick cookware
- Stain-resistant fabrics
- Coatings on some food packaging
- Components of fire-fighting foam
- Many industrial applications
PFAS have been found in Minnesota groundwater.
Since many PFAs are new to the environment and drinking water there are no testing levels indicated yet.
- Treatment options and guidance:
- Alternative water source
- Carbon filter
- Reverse osmosis
CECs are new substances found in drinking water that do not have enough data to produce health risk limits. These can include substances such as medication bi-products, cosmetics, hormones, industrial chemicals, pharmaceuticals, etc.
Many of these contaminants have been produced in recent years and are just starting to show up in drinking water.
The Minnesota Department of Health has more information on current studies about CEC.
Hardness
Caused primarily by calcium and magnesium, hardness in water is simply a measure of the number of dissolved metals.
There is no health risk limit for hardness, just the annoyance of dingy clothes, scum and staining from the water on hard surfaces.
- Treatment options and guidance:
- Water softening, also known as cation exchange.
Reviewed in 2021