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Minneapolis Drinking Water Reports and Guide

The City of Minneapolis draws surface water from the Mississippi River to supply water to its residents. Surface water is prone to algae growth and decaying organic material. Algae blooms and decaying aquatic plants cause the “fishy”, swampy, earthy, musty taste and smell reported every spring. Heavy rains and melting snow can wash chemicals, herbicides, and pesticides from agriculture and industry into rivers. 99 rural Minnesotan communities still release sewage into lakes and streams due to a lack of funds for infrastructure improvements.

Minneapolis Water Disinfection and Treatment

Because the Mississippi is a relatively dirty water source, Chlorine and Ammonia, which form Chloramines are added for disinfection. These give Minneapolis drinking water an occasional “swimming pool taste”.

Minneapolis Water contains an average of 3.5 – 4.0ppm of Chlorine

The Mississippi River naturally contains moderate levels of Hard Water Minerals and Iron. Ferric Chloride is added to help reduce the brown/yellow color of the source water. A chemical softening process is also used to reduce water hardness from 14 grains down to 5-6 grains. Lastly a poly/ortho phosphate is added to help reduce the corrosive effects of the disinfectants.

Minneapolis Water Main Break

Minneapolis Water Main Breaks

Minneapolis has the largest distribution system in the Midwest. There are roughly 1,000 miles of unlined cast iron pipe.

Minneapolis water mains are 80-100 years old, and average 1 water main break per week.

In January 2013, a massive Minneapolis water main break flooded several city blocks. The 36″ water main dumped out over 14 million gallons of water Minerals like Iron and sediment build up in old pipes throughout the city.

This causes water discoloration and requires periodic flushing to prevent “Minneapolis Muddy Waters”. Minneapolis is now upgrading 10 miles of pipe each year to overcome this discoloration (Making it a 100 year project).

Minneapolis Water Reports

The City of Minneapolis does regular water testing and publishes the results in Annual Drinking Water Reports. These reports explain which water contaminants, and what levels have been found.


The EPA has two standards for drinking water contaminants:

MCL: Maximum Contaminant Level
The legal limit for a certain contaminant

MCLG: Maximum Contaminant Level GOAL
The level with ZERO HEALTH RISKS, aka the “Health Limit”

All water contaminants meet the EPA’s “Legal Limit”. Contaminants that exceed the EPA’s Health Limit have been highlighted below.

Inorganic Contaminants

Inorganic contaminants include natural and manmade salts and metals. You are mostly exposed to inorganics through drinking water, most do not easily pass through skin. Carbon Filters (refrigerator and faucet filters) have almost ZERO impact on these contaminants. Reverse Osmosis very effective at removing inorganic contaminants.

Contaminant Amount Found Health Limit Legal Limit Potential Effects
Cyanogen Chloride 1.91-5.33 50 NA toxic gas that was used as a poison; it is also utilized by the chemical industry and in mining and metalworking.
Fluoride 0.98-3.77 4 4 Bone disease;children may get mottled teeth
Nitrate 0.4-2.2 10 10 Blue-baby syndrome

Organic Contaminants

Organic contaminants can come from either natural sources like algae, or man-made chemicals. You can be exposed through drinking water, absorption through skin (bathing), and inhalation. This makes a Hybrid Filter System, or Whole House Carbon Filter a good preventative tool.

Contaminant Amount Found Health Limit Legal Limit Potential Effects
Atrazine 0.15-0.30 3 3 Cardiovascular or reproductive problems
Carbon Tetrachloride 0.7 0.6 5 Liver problems; increased risk of cancer
Tetrachloroethylene 0.06-0.6 0 5 Liver problems; increased risk of cancer
Total Organic Carbon 3.1-6.0 NA NA High levels of TOC increase disinfection byproducts

Disinfectants and Disinfection Byproducts

Disinfectants are added to kill bacteria. Disinfectants like Chlorine react with other chemicals and create “Disinfection Byproducts. These chemicals enter the body through inhalation, absorption through skin, and drinking water. A Whole House Carbon Filter is a good preventative tool in addition to a Drinking Water System for these compounds.

Contaminant Amount Found Health Limit Legal Limit Potential Effects
Chlorine 3.0-4.1 4 4 Eye/nose irritation; stomach discomfort
Chloroform 25.29-62.0 5.7 80 Nervous system depression, increase in kidney and liver tumors
Haloacetic Acids 10.2-55.5 0 80 Increased risk of cancer
Total Trihalomethanes 14.9-80 0 60 Increased risk of cancer

Microbial Contaminants

Microbes like bacteria and virus come from a variety of sources. These include water main breaks, leaky septic systems, livestock, and wildlife. Microbial contaminants are mainly consumed through drinking water. Carbon Filters and Water Softeners do not offer any protection against microbes, but UV Treatment is very effective.

Contaminant Amount Found Health Limit Legal Limit Potential Effects
Cryptosporidium 5-119*** 0 115(oocysts/100L) Short-term exposure: Gastrointestinal illness (diarrhea, vomiting, cramps)
Giardia 7.0-435*** 0 149(cysts/100L) Short-term exposure: Gastrointestinal illness (diarrhea, vomiting, cramps)
Mammalian Virus 1.0-37.0*** 0 9.5(MPNX/100L) Short-term exposure: Gastrointestinal illness (diarrhea, vomiting, cramps)
Total coliform bacteria 1%**** 0 5% Not a health threat itself; it is used to indicate whether other potentially harmful bacteria may be present
Turbidity 0.28-0.56 NA NA Turbidity measures water cloudiness. It is used to indicate water treatment effectiveness (e.g., whether disease-causing organisms are present). Higher turbidity levels are often associated with higher levels of disease-causing microorganisms such as viruses, parasites and some bacteria. These organisms can cause short term symptoms such as nausea, cramps, diarrhea, and associated headaches.
*Upon re-testing, 0% Coliform Bacteria was detected.

Radionuclide Contaminants

Radionuclides in water may occur naturally, or come from oil and gas production or mining activities. These can be inhaled, or consumed through drinking water.

Contaminant Amount Found Health Limit Legal Limit Potential Effects
Alpha Emitter 0.4 0 15.4 Increased risk of cancer

This information was compiled from Minneapolis’ water treatment reports, the Environmental Protection Agency(EPA), Minnesota Department of Health(DOH), World Health Organization(WHO), and Environmental Working Group(EWG). Please contact us if there are any missing contaminants, or levels that differ from those outlined on this page.

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