Bureau of Drinking Water & Groundwater • Wisconsin Department of Natural Resources • PUB-DG-035 2001
Iron in Drinking Water
Introduction experience red, brown, or yellow stain-
ing of laundry, glassware, dishes, and
Finally, when iron exists along with cer-
tain kinds of bacteria, problems can
I ron is one of the earth’s most
plentiful resources, making up at
least five percent of the earth’s crust.
household fixtures such as bathtubs and
sinks. The water may also have a metal-
lic taste and an offensive odor. Water
become even worse. The bacteria con-
sume iron to survive and leave a red-
dish brown or yellow slime that can
When rainfall seeps through the soil, system piping and fixtures can also clog plumbing and cause an offensive
the iron in the earth’s surface dissolves, become restricted or clogged. odor. You may notice this slime or
causing it to go into almost every natu- sludge in your toilet tank when you
ral water supply, including well water. remove the lid. For more information
Although iron is present in our water, Types of Iron on iron bacteria, contact your DNR
it is seldom found at concentrations Regional Office and ask for the DNR
greater than 10 milligrams per liter
(mg/l) or parts per million (ppm).
I ron is generally divided into two
main categories: 1) soluble and
2) insoluble. Soluble iron, or “clear
publication, “Iron Bacteria Problems in
water” iron, is the most common form Once you determine whether you have
“clear water,” “red water,” “organic”
Health and and the one that creates the most com-
plaints by water users . This type of or “bacterial” iron in your water, you
Water Quality iron is identified after you’ve poured a can take steps to correct the problem.
glass of cold clear water. If allowed to Keep in mind that no one treatment
I ron is not considered hazardous to
health. In fact, iron is essential
for good health because it transports
stand for a few minutes, reddish brown
particles will appear in the glass and
method will work for every type of iron
eventually settle to the bottom.
oxygen in your blood. In the United
States, most tap water probably sup-
plies less than 5 percent of the dietary
When insoluble iron, or “red
water”iron is poured into a glass, it
Test Your Water
requirement for iron.
Under Department of Natural
appears rusty or has a red or yellow
color. Although not very common in
Wisconsin’s water wells, insoluble iron
B efore you attempt to remove
anything that appears to be
iron-related, it is important to have your
Resources (DNR) rules, iron is consid- can create serious taste and appear- water tested. A complete water test to
ered a secondary or “aesthetic” con- ance problems for the water user. determine the extent of your iron prob-
taminant. The present recommended lem and possible treatment solutions
limit for iron in water, 0.3 mg/l (ppm), Because iron combines with different
should include tests for iron concentra-
is based on taste and appearance naturally occurring acids, it may also
tion, iron bacteria, pH, alkalinity, and
rather than on any detrimental health exist as an organic complex. A combi-
effect. Private water supplies are not nation of acid and iron, or organic
subject to the rules, but the guidelines iron, can be found in shallow wells If you receive your water from a public
can be used to evaluate water quality. and surface water. Although this kind water system and experience red water
of iron can be colorless, it is usually problems, it is important to contact a
For instance, when the level of iron in yellow or brown. utility official to determine whether the
water exceeds the 0.3 mg/l limit, we red water is from the public system or
your home’s plumbing or piping.
H igh iron levels may be avoided
in some cases by changing the
screen or casing depth interval of the
well as long as the minimum casing
depth requirements are still met. Talking
to your neighbors about their well
depths and iron levels will give you
some idea of what well depth would
pump the lowest amount of iron. It is
also helpful to talk to a well driller or
pump installer about local conditions Street, Madison, WI 53715 and ask 3. Will the treatment unit treat the
and the cost of drilling a new well in for publication G3558-5, “Choosing a water at the flow rate required for
your area. The cost of well work should Water Treatment Device.” my water system?
be compared to the long term (perhaps
When choosing a water treatment 4. Considering the results of my water
twenty years) cost of treating the water
method or device, make sure you have test, will this method effectively
for any iron related problems.
answers to the following five questions: remove iron? (For example, pH
may need to be adjusted before
1. What form of iron do I have in my
Treatment water system?
beginning a particular treatment).
5. Would well construction or recon-
T able 1 lists treatment consider
ations for the various forms of
iron. For additional information on
2. Will the water treatment unit
remove the total iron concentration
(determined by the water test) in
struction be more cost effective than
a long term iron removal treatment
water treatment systems, contact your my water supply? (Total iron refers
County Extension Office or Extension to both soluble and insoluble iron
Publications, Rm. 245, 30 N. Murray combined).
Table 1: Treatment considerations for various forms of Iron.
Characteristic Known As Treatment Methods Considerations
Drawn tap water is clear and colorless. Soluble Aeration/Filtration May require lengthy contact time. Temperature dependent.
When allowed to stand, reddish brown Clear Water
particles appear and settle to bottom. Fe+2 Water softener Hardness must be calculated. System must be airtight.
Ferrous All water must be treated.
Dissolved Chlorination/Filtration Chlorine liquid or pellets. Frequent monitoring. Proper water pressure.
Manganese greensand/ Filtration Adequate pressure.
Catalytic filtration “BIRM” Dissolved oxygen, organic matter, chlorination, polyphosphate, temperature
Ozonation Used by some municipal systems. Expense.
Sequestering May not prevent staining. May need to remove sequestering agents and iron.
Test for agents before choosing another treatment device.
Drawn tap water appears rusty or Insoluble Manganese greensand/ Filtration Adequate pressure.
has a red or yellow color. Red Water
When allowed to stand Fe+3 Catalytic filtration “BIRM” Dissolved oxygen, alkalinity, organic matter, chlorination, polyphosphate,
particles settle to bottom. Ferric temperature limitations.
Oxidized Chlorination/Filtration Chlorine liquid or pellets. Frequent monitoring. Proper water pressure.
Water tank/toilet tank/plumbing have Bacterial Shock chlorination and consider following with Shock chlorination should include; cleaning the well thoroughly, cleaning pump
reddish brown or yellow gelatinous Creno-thrix continuous chlorination. and riser pipe, and complete chlorination and flushing of distribution system.
slime or sludge present. May have Leptothrix Bactericides. Make sure bactericides can be used in drinking water. Bactericides need long
objectionable odor or oily sheen. Gallionella contact time for adequate treatment.
High color content (yellow or brown) Organic Water softener First step is to treat for organics. Hardness must be calculated.
or colorless. Generally groundwater Hemme System must be airtight. Treat all water.
from shallow well or surface water. Tannin
Manganese greensand/ Filtration First step it to treat for organics. Adequate pressure.
Ozonation Used by some municipal systems. Expense.
Aeration: Introducing oxygen to the water source zycnzj.com/http://www.zycnzj.com/
to convert Ozonation: A specialized form of aeration using ozone to convert soluble
soluble iron to its insoluble form. iron.
Filtration: Media used to entrap and screen out oxidized particles of iron. Ion Exchange: Substituting an acceptable ion (such as sodium) for soluble
Usually requires backwashing to remove accumulated iron. iron.
Water Softener: Removal of soluble iron by ion exchange. Sequestering: Adding chemical agents to water to keep metals like iron
in solution to prevent characteristic red stains.
Manganese Greensand: An ion exchange sand material which is
capable of removing iron. Adsorbs dissolved iron and requires chemical Chlorination: Chemical oxidizer used to convert soluble iron to an insolu-
regeneration. ble, filterable form.
Catalytic Filtration “BIRM”: A granular filter medium that enhances the
reaction between oxygen and iron and then filters the insoluble iron.
State of Wisconsin
Additional Department of Natural Resources
Remember, the type of water you DOUGLAS Regional Boundaries
have will determine what type of IRON Region Offices
treatment is possible. No one NORTHERN
treatment technique works for WASHBURN SAWYER
every iron problem and well
construction or reconstruction
may be more cost effective.
BURNETT POLK MARINETTE
For additional information on BARRON RUSK
iron in drinking water, contact LINCOLN
a water treatment dealer, a TAYLOR OCONTO
water supply specialist at one ST. CROIX DUNN
of the DNR Regional offices MARATHON MENOMINEE
listed on this page or in the: WEST CENTRAL CLARK
PIERCE EAU CLAIRE SHAWANO
DNR Bureau of Drinking PEPIN
Water and Groundwater BUFFALO OUTAGAMIE
Box 7921 JACKSON
Madison, WI 53707-7921 BROWN
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