Tap water OR bottled water?
MN Department of Health analysis.
Duluth, MN Drinking Water Quality:
City of Duluth Water Quality Information:
Superior, WI Drinking Water Quality:
Well Testing and Groundwater Information:
Drinking water in the Duluth area primarily comes from Lake
Superior via the City Water Treatment Plant or from private
residential wells in rural areas. There are also a small
number of systems, mostly from resorts, that draw water from
The Minnesota Department of Health
(MDH) is responsible for ensuring
a safe drinking water supply for Minnesotans under the
provisions of the federal Safe Drinking Water Act (SDWA).
Learn how the drinking water system in Duluth works in this report by the EPA (1.1MB pdf) or view a slide presentation on the city's infrastructure (3.3 MB pdf).
In the City of Duluth, the Water Treatment Plant draws water
from Lake Superior, several miles east of the Lester River
from a depth of about 55 m (180 ft), filters it to remove
particulate material, disinfects it with chlorine, and then
pumps it to reservoirs throughout the City. Staff perform
a variety of water quality analyses, some every day, others
every 3 months, for a suite of over 100 chemicals. These
data may be obtained by contacting either the City Water
Treatment Plant in Lakewood Township at 218/525-0834, the
Duluth Office of the MDH ( 218/723-4651), or via the main
office in St. Paul (651/215-0770).
Since March of 1989 the City has added a caustic soda (50% NaOH) solution until the final pH of the treated water reaches pH 9.00. This is the only corrosion control step that is now taken. Prior to this a low concentration of zinc phosphate was added. At consumer taps the pH will not be that high and usually is in the 8.0 - 8.5 range since the sodium hydroxide does not provide buffering. The final hardness and alkalinity are about the same in the treated water as for the raw water pumped from Lake Superior at 46 ppm which is indicative of a very "soft" water (L. Janson, City of Duluth, Jan 2014).
Drinking water from private wells is less regulated. There
are standards for well construction and well-drillers must
be certified by the MDH but there are no monitoring requirements.
Prudent homeowners should familiarize themselves with proper
operation and maintenance of their well and consider periodic
monitoring of their drinking water quality for at least nitrate
and total coliform bacteria annually, and at least once for
arsenic, lead, volatile organic chemicals and pesticides.
There is good information about wells and groundwater in
State agency and University of Minnesota Sea Grant websites
(see box), and possibly about your particular well in the
Computerized County Well Index (CWI) developed by the Minnesota
Geological Survey (see box below).
Surface water systems for resorts are also regulated by
the MDH (see Noncommunity public water systems below) and
now require filtration and disinfection.
MDH is also responsible for source water protection
- Wellhead Protection
- Source Water Assessments
- Protection of Surface Water Intakes
SAFE DRINKING WATER
Diseases caused by unsafe drinking water and poor sanitation are among the world's most
serious public health threats, accounting for nearly 80 percent of illnesses in developing
countries and killing millions of people - mostly children - each year.
Learn more about this problem and explore possible solutions.
City Water Supply
Community public water supplies serve at least 26 persons
or 15 service connections year-round, which includes municipalities,
manufactured mobile home parks, etc. Duluth is one of about
1,000 community water supply systems in Minnesota. These
systems are required to provide a safe and adequate supply
of water under the federal Safe
Drinking Water Act (SDWA).
The City of Duluth Water
Supply Section of the Department of Public Works is
responsible for operating and maintaining the drinking
water treatment plant that filters and disinfects our source
water from Lake Superior and the pipes and, pumps and reservoirs
that deliver the water to our homes.
Department of Health Community Water Supply Unit is
responsible for assuring the compliance of community water
supply systems with the SDWA. The Unit consists of field
staff located in MDH's district offices and compliance
staff located in St. Paul. Unit field staff provide on-site
technical assistance to community water supply systems
and conduct much of the testing for smaller community systems,
sending most samples to St. Paul for analyses. All community
water supplies are tested for contaminants such as pesticides,
solvents, and metals as well as "conventional pollutants" such
as bacteria and nitrate.
County Well Index (CWI)
How to find
out about your home's well (you should know this number!)
The County Well Index (CWI) is a computerized
data base that contains basic information for over 300,000
water-wells drilled in Minnesota. The data is derived from
water-well contractors' logs of geologic materials encountered
during drilling. Geologic well records are available for
approximately 200,000 of the wells. Available data also
includes casing, screen and pump information. The CWI data
is available online at the University
of Minnesota's Minnesota Geological Survey or it can
be ordered on a CD for $15.00 from the MGS Map Sales Office.
- General Information
- Map Sale office
(612) 627-4782 or
(612) 627-4780 ext. 238
- Water-Well Help Line
(612) 627-4780 ext. 240
- Surface mail address
Minnesota Geological Survey
2642 University Ave. W.
St. Paul, MN, USA 55114-1057
Noncommunity public water systems
include schools, factories, restaurants, resorts, and churches
that are served by their own supply of water (usually a
well). These facilities also must provide a safe supply
of water under the federal SDWA. They serve either a nontransient
(same people each day such as a school, daycare, or factory)
or a transient population (different people each day such
as a restaurant, motel, or highway rest area), each being
regulated. Read more about these systems at the
Minnesota Department of Health.