FAQs - Water Quality and Public Health

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Milwaukee's pure, fresh high-quality water

Internal Link Bottled water vs. tap water
Internal Link Chlorine in drinking water treatment
Internal Link Compromised immune systems - information
Internal Link Cryptosporidium
Internal Link Do not drink from the garden hose
Internal Link Do not drink from the hot water tap
Internal Link Fish aquarium water information
Internal Link Fluoride
Internal Link Home brewers and hobbyists water quality information
Internal Link Ice Cubes - why they can be cloudy
Internal Link Lead and drinking water
Internal Link Pharmaceuticals and personal care products (PPCPs)
Internal Link Radon
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Source of Milwaukee water

Internal Link Protect source water: Recycle electronics
Internal Link Water filters
Internal Link Water hardness
Internal Link Water treatment process


Milwaukee's pure, fresh high-quality water

Read the 2013 Water Quality Report (EPA-required Consumer Confidence ReportEnglish   en español

The Milwaukee Water Works is a national leader in providing pure and healthful drinking water, and is recognized for its water community-leading water quality monitoring, or testing. Milwaukee water quality meets all Wisconsin Department of Natural Resources and U.S. Environmental Protection Agency (EPA) standards, or regulations, for healthful drinking water.

The EPA requires water utilities to test for 91 regulated contaminants in an ongoing basis. The Milwaukee Water Works goes beyond those requirements and tests for over 500 known contaminants to assure you receive the highest quality water. Read an overview of the water quality monitoring program, and find water quality reports in the Water Quality section.

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Bottled water vs. tap water

We suggest you fill your reusable, recyclable water container with Milwaukee water. Of all of the choices of water available to you, only one must meet all standards of the Safe Drinking Water Act: your Milwaukee tap water.

Milwaukee’s drinking water quality meets all state and federal health regulations.

Compared with the price of purchased bottled water, Milwaukee water is a a bargain. Two-and-one-half gallons of Milwaukee water cost one cent. And, with Milwaukee water, you receive the benefits of highly regulated water quality along with fluoride for the health of your teeth.

The U. S. Food and Drug Administration (FDA) requires bottled water quality standards to be equal to those of the EPA for tap water, but the government does not monitor the quality of the finished bottled water product. Bottlers must test their source water and finished product only once a year. The Milwaukee Water Works conducts a multitude of quality tests on a daily, continuous basis. 

Public water supplies must assess sources of potential contaminants, but federal rules specify no requirements, like setbacks from dumps, industrial facilities or underground storage tanks, for the protection of bottled water sources.

Why doesn't the Milwaukee Water Works bottle its water?
•    The core business of the Milwaukee Water Works is to provide safe, high quality drinking water at every tap. Bottling water is another business and would compromise that focus. We choose not to use ratepayer revenue to invest in bottling Milwaukee water. Instead, we reinvest any revenue into utility infrastructure.
•    Bottling the water would send mixed messages to consumers about the quality of the water in the bottle, sending more bottles to landfill, and would pose questions about the health risks of using certain plastics.
•    We encourage everyone to fill at the tap and enjoy! Wash, reuse and recycle your bottles.

Milwaukee was one of the first U.S. cities to test its water for emerging contaminants like pharmaceuticals. None have been found in Milwaukee’s treated drinking water. Milwaukee was the first U.S. city to post the results on the Internet, demonstrating a commitment to water quality and transparency to our customers.

We purify Lake Michigan water with a multiple-step process that destroys illness-causing microorganisms and harmful contaminants. Since 1993, the Milwaukee Water Works has invested $417 million in its infrastructure, from treatment plants to distribution systems, to ensure a reliable supply of high-quality drinking water.

The Milwaukee Water Works has great confidence in the water we deliver to your home, school, and business, and would like you to have the same confidence.

The Milwaukee Water Works provides healthful, safe drinking water to Brown Deer, Butler, Franklin, Greendale, Greenfield, Hales Corners, Menomonee Falls, Mequon, Milwaukee, New Berlin, Shorewood, St. Francis, Thiensville, Wauwatosa, West Allis, West Milwaukee, and the facilities of the Milwaukee County Grounds.
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 Chlorine in Drinking Water Treatment

Chlorine is used as a disinfectant by most public water systems to kill harmful microorganisms during the water treatment process. The use of chlorine, in carefully controlled dosages, provides a significant public health improvement. The Milwaukee Water Works uses a liquid form of chlorine.

As the water leaves the treatment plant, ammonia is added to change the free chlorine to chloramine. This is a very stable form of chlorine disinfectant that maintains the residual protection in the distribution system. The Wisconsin Department of Natural Resources (DNR) requires water utilities to maintain a detectable level of disinfectant throughout the distribution system to maintain bacteriological protection. 

The Disinfectants/Disinfection Byproduct Rule sets a maximum chlorine level of 4.0 mg/L (4.0 ppm) for finished water. The DNR requires the water leaving a treatment plant to have a minimum chlorine level of 1.0 mg/L (1.0 ppm). The water leaving Milwaukee's two treatment plants has a chlorine residual in the range of 1.22 - 2.00 mg/L.

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Compromised immune systems - information

Some people are more vulnerable to contaminants in drinking water than the general population. Persons with compromised immune systems are particularly at risk from infections. This could include persons undergoing chemotherapy, persons who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly persons, and infants. These persons should seek advice about drinking water from their health care providers.

The City of Milwaukee Health Department, in collaboration with the Milwaukee Water Works, prepared a brochure based on U.S. Environmental Protection Agency (EPA) and Centers for Disease Control (CDC) guidelines on appropriate means to lessen the risk of infection by Cryptosporidium. Read this information in English or Spanish. Or, print a two-sided brochure in English or Spanish. Additional information is available from the Centers for Disease Control (CDC) and the EPA.

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Cryptosporidium is a microscopic protozoan that when ingested, can result in diarrhea, fever, and other gastrointestinal symptoms. The organism is found in 97% of all surface water sources including lakes, rivers and streams. 

Twenty years ago on April 7, 1993, the City of Milwaukee issued a boil water advisory on the probability the illness-causing micro-organism Cryptosporidium had passed through the city’s drinking water treatment system and into the finished water. After seven days, the advisory was lifted, and Milwaukee officials vowed there would never again be a waterborne illness event. The City has kept its pledge to upgrade the Milwaukee Water Works (MWW) water treatment and delivery system and improve water quality monitoring.

Milwaukee's drinking water meets or exceeds all Wisconsin Department of Natural Resources (DNR) and U.S. Environmental Protection Agency (EPA) standards. The Milwaukee Water Works conducts a rigorous water quality monitoring program to ensure safe, healthy water and to gather data to assist regulators in setting standards for emerging contaminants. 

The events of 1993 led to improvements worldwide in water quality treatment processes, water quality monitoring, and regulations to protect the public health. In particular, the ongoing partnership between the MWW and the Milwaukee Health Department for water quality monitoring and public health surveillance, ground-breaking at the time, is now recognized nationally for its effectiveness in protecting public health. The Advisory Council developed an early warning disease surveillance network and procedures to notify the public and respond in the event of drinking water contamination or a disease outbreak. 

The City of Milwaukee Health Department and the Milwaukee Water Works have prepared a brochure (English) (Spanish) based on EPA and CDC guidelines on appropriate means to lessen the risk of infection by Cryptosporidium. A copy of this brochure is also available from the Milwaukee Water Works Customer Service Center, 841 N. Broadway or call (414) 286-2830. 

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It's not safe to drink from a garden hose

It is not safe to drink from garden hoses. Vinyl hoses are treated with chemicals so they stay flexible. These chemicals may be toxic which is why garden hoses should not be used for drinking purposes. Sunlight heats the hose, speeding up the leaching of chemicals from the hose.

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It's not safe to drink water from the hot water tap

Water from the hot water faucet should not be used for drinking or food or beverage preparation. Hot water systems (tanks, boilers) contain metallic parts that corrode over time and contaminate the water. Hot water is more corrosive than cold water and is more likely to contain unhealthy compounds.

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What are my fish swimming in? Fish aquarium water information

Milwaukee Water Works water contains chloramines to keep the water bacteria-free after it leaves the water treatment plants. Chloramines are toxic to fish so aquarium keepers must dechlorinate Milwaukee drinking water before using it for fish. You can find dechlorinating agents at tropical fish and pet stores.

The amount of ammonia in Milwaukee water is not harmful to fish. The amount, less than 0.3 milligrams per liter, is below the detection level of the test kits typically used to test for ammonia in aquaria. Fish give off nitrogenous wastes that break down into ammonia. Also, be aware that ammonia tests are easily affected by ammonia that is present in cleaning products such as glass cleaner. Here is some general parameters and measurements of  Milwaukee water quality.

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Fluoride, in low levels in drinking water, is proven to help prevent tooth decay. Milwaukee began adding fluoride to its water in 1953 when the Common Council enacted an ordinance directing its use. The American Dental Association (ADA) endorsed fluoridation in 1950 and reaffirmed its endorsement in 1997. The American Medical Association also endorsed fluoridation and reaffirmed its use, in 1951 and 1996, respectively. The U.S. Public Health Service has also endorsed fluoridation. (Source: American Water Works Association)

At the direction the City of Milwaukee Mayor and Common Council who direct policies for your water utility, and based on determinations of health professionals, the Milwaukee Water Works adds fluoride to your drinking water. As of Aug. 31, 2012, Milwaukee water is fluoridated at a level not to exceed 0.7 mg/L. Find more  information on the websites of the Centers for Disease Control www.cdc.gov/fluoridation, Health and Human Services www.hhs.gov, and the Milwaukee Health Department http://city.milwaukee.gov/Health.
Notice to Parents of Infants Six Months of Age or Younger
According to the Centers for Disease Control, the proper amount of fluoride from infancy throughout life at all ages helps prevent and control tooth decay (cavities). Therefore, the Milwaukee Water Works, following public health recommendations, maintains a level of fluoride in the drinking water that is both safe and effective.

Per Common Council File No. 120187 adopted on July 24, 2012, the utility is required to post the following advisory regarding fluoride and young infants: 
The American Academy of Pediatrics recommends exclusive breastfeeding for the first six months of a child’s life, followed by continued breastfeeding as complementary foods are introduced, for optimal short- and long-term health advantages. Go to >http://pediatrics.aappublications.org/content/129/3/e827.full> for more information. As of Aug. 31, 2012, Milwaukee water is fluoridated at a level not to exceed 0.7 mg/L. According to the Centers for Disease Control (CDC), for infants up to six months of age, if tap water is fluoridated or has substantial natural fluoride (0.7 mg/L or higher) and is being used to dilute infant formula, a parent may consider using a low-fluoride alternative water source. Bottled water known to be low in fluoride is labeled as purified, deionized, demineralized, distilled, or prepared by reverse osmosis. Ready-to-feed (no-mix) infant formula typically has little fluoride and may be preferable at least some of the time. If breastfeeding is not possible, parents should consult a pediatrician about an appropriate infant formula option. Parents should be aware that there may be an increased chance of mild dental fluorosis if the child is exclusively consuming infant formula reconstituted with fluoridated water. Dental fluorosis is a term that covers a range of visible changes to the enamel surface of the tooth. Go to http://www.cdc.gov/fluoridation/safety/infant_formula.htm> for more information on dental fluorosis and the use of fluoridated drinking water in infant formula.

Aviso para los padres de niños pequeños y de hasta seis meses de edad
De acuerdo a los Centros para el Control y la Prevención de Enfermedades (CDC, Centers for Disease Control and Prevention), la cantidad adecuada de fluoruro desde la infancia y en todas las etapas posteriores de la vida ayuda a prevenir y controlar las caries dentales. Por esta razón, el Departamento de Agua de Milwaukee adopta las recomendaciones sobre salud pública y, en consecuencia, mantiene en el agua potable un nivel de fluoruro sano y eficaz. En cumplimiento de lo dispuesto por el registro del Consejo Municipal (Common Council) número 120187, adoptado el 24 de julio del 2012, estamos obligados a publicar la siguiente notificación acerca del fluoruro y los niños pequeños:

“La Academia Estadounidense de Pediatría (American Academy of Pediatrics) recomienda la leche materna como único alimento en los primeros seis meses de vida. Y, a partir de entonces, la continuación de la lactancia mientras se incorporan alimentos complementarios a la dieta, para fomentar el buen estado de salud a corto y largo plazo. Para más información, visite <http://pediatrics.aappublications.org/content/129/3/e827.full>. Desde el 31 de agusto del 2012 , el agua de la Ciudad de Milwaukee se suministra con un nivel de fluoruro de 0.7 mg/L. Según datos de los CDC, si el agua es fluorada o naturalmente tiene un nivel considerable de fluoruro (0.7 mg/L o más), se recomienda que los niños pequeños de hasta seis meses de edad consuman una fuente de agua alternativa con poco fluoruro si los padres utilizan agua de la llave para mezclar o diluir fórmula alimenticia para el pequeño. El agua en botella con baja concentración de fluoruro contiene en la etiqueta las palabras: purificada, desionizada, desmineralizada, destilada o preparada por ósmosis inversa (purified / deionized / demineralized / distilled / reverse osmosis). La fórmula lista para consumir (ready to feed) suele tener poco fluoruro y puede ser una opción en algunas ocasiones. Si no es posible amamantar, los padres deben preguntarle al pediatra cuál es la mejor opción de fórmula. Los padres deben tener presente que los bebés que se alimentan exclusivamente con fórmula preparada con agua fluorada pueden tener una mayor probabilidad de sufrir una leve fluorosis dental. El término “fluorosis dental” abarca una variedad de cambios en la superficie del esmalte de los dientes. Visite <http://www.cdc.gov/fluoridation/safety/infant_formula.htm> para más información sobre fluorosis dental y el uso de agua potable fluorada en la fórmula para lactantes.”

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Home brewers and hobbyists water quality information

Milwaukee's water is of exceptional quality for home brewing. Here is some basic water quality information that you may need if you use Milwaukee tap water for brewing, aquariums, home photography, and other hobbies. See also FAQ Fish aquarium water information.

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Ice cubes - why they can be cloudy

Ice crystals trap air as they form and the water freezes. This can make ice cubes look cloudy. 

Minerals in the water and soap residue in the tray can cause ice cubes to stick to the tray. Try cleaning the ice cube trays with vinegar. Wash and rinse thoroughly before refilling with water.

You may notice water from your faucets tastes wonderful, but the water from the dispenser in your refrigerator and the ice cubes taste dirty. The taste may be the result of buildup in the automatic ice maker, the water dispenser, and the hoses leading from your water source to the refrigerator. Follow the manufacturer's directions for operation and maintenance of your refrigerator to clean those parts and replace them and any filters as necessary.

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Lead and drinking water

Water is a minor contributor to the problem of lead poisoning, but the Milwaukee Water Works takes a proactive approach to protecting customers from lead in drinking water. The Milwaukee Water Works has not detected lead in its treated water or source water since it began testing for lead in 1992.

Water absorbs lead from solder, fixtures, and pipes found in the plumbing of some buildings and homes. Where high levels of lead are found in water, the most common sources are lead-based solder used to join copper pipe, faucets made of brass and chrome-plated brass, and in some cases, pipes made of lead that connect a home to the water main.

According to the U.S. Environmental Protection Agency (EPA), two types of homes are primarily at risk from lead contamination from drinking water:

  • homes built before 1940 with lead services or lead pipes
  • homes built between 1982 and 1987, which used copper pipe with lead-based solder.

In 1986, Congress banned the use of solder containing more than 0.2% lead and restricted the lead content of faucets, pipes, and other plumbing materials. Houses that have copper services do not have measurable lead in the water.

The Milwaukee Water Works began a corrosion control program in 1996, which has resulted in a significant improvement in lead at customers' taps. We add a phosphorous compound to the water that forms a coating on the inside of pipes to prevent lead from leaching from plumbing materials into the water. In accordance with EPA regulations, MWW tested for lead every year from 1996 to 2002 at selected "at-risk" homes identified by the EPA as containing certain plumbing features that might contain lead. In 2002, the EPA notified the Milwaukee Water Works it is in compliance with regulations, meets optimal corrosion control parameters and directed a modified monitoring program. If monitoring in a home indicates lead levels exceed EPA action levels, the MWW advises those residents of the results and provides guidance on how to reduce exposure to lead in drinking water.

Concerned residents can take several steps to further limit possible exposure.

  • Flush your kitchen water tap. This is a simple method to avoid high lead levels. Let the cold water run from the faucet, until noticeably colder, about one to two minutes, before using it for drinking or cooking any time the water in the faucet has been unused for more than a few hours.
  • Do not cook with or drink water from the hot water tap. Hot water is more corrosive than cold water and is more likely to contain lead.
  • To learn if lead is present in your home drinking water, arrange to test your water, at your own cost, by a state-certified laboratory.

Infants and young children are typically more vulnerable to lead in drinking water than the general population. It is possible that lead levels in your home may be higher than at other homes in the community as a result of materials used in your house plumbing. For additional information call the EPA Safe Drinking Water Hotline, 800-426-4791.

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Pharmaceuticals and Personal Care Products (PPCPs)

Today's advanced water monitoring technology allows researchers to detect compounds from pharmaceuticals and personal care products in very small amounts in waterways and, in some cases, drinking water supplies. While research hasn't demonstrated human health impacts at these levels, the water community continues to pay close attention to scientific developments in this area.

PPCPs are products that are used as pharmaceuticals or for personal care. They include antibiotics, anti-inflammatory medicines, cough syrup, fragrances, hormones, and pain medication. They can be excreted from the body (usually in urine), flushed into toilets, and can pass through sewerage treatment plants into surface waters, rivers, etc. 

Because water professionals have the technology today to detect more substances - at lower levels - than ever before, pharmaceutical compounds and personal care products are being found at very low levels in some of our nation's lakes, rivers and streams.

The fact that a substance is detectable does not mean the substance is harmful to humans. To date, research throughout the world has not demonstrated an impact on human health from pharmaceuticals at the low levels found in some drinking water supplies.

While pharmaceuticals and personal care products are rarely found even in very low levels in drinking water, some scientists are concerned about the possible cumulative effects of long-term exposure. While most pharmaceuticals and personal care products are known compounds, they may react in ways that are different from their intended purpose once they are introduced into the environment.

In Milwaukee, the most recent tests found none of these contaminants in Milwaukee's drinking water. Many contaminants have been found in Lake Michigan water, which Milwaukee treats to ensure safe, healthy drinking water. According to the U.S. Environmental Protection Agency (EPA), Milwaukee's drinking water is exceptional in quality and exceeds all standards set by water quality regulators.

Pharmaceuticals and personal care products in water have been a concern of water utilities and the American Water Works Association and U.S. Environmental Protection Agency for some time. Milwaukee is a national leader in producing high quality water and monitoring water quality. Since 1993, the Milwaukee Water Works has invested over $417 million in its treatment, monitoring, and distribution systems to ensure a reliable supply of high-quality water. The utility treats Lake Michigan water with ozone as the primary disinfectant. Ozone destroys microorganisms and harmful compounds that can cause illness. It reduces the formation of disinfection byproducts, and removes source water taste and odor. Coagulation, settling, biologically active filtration, fluoridation, and chloramine disinfection ensure high-quality water throughout the distribution system.

The Milwaukee Water Works is not affiliated organizationally with the Milwaukee Metropolitan Sewerage District, which treats waste water and returns the effluent to Lake Michigan.

The Milwaukee Water Works was one of the first utilities in the U.S. to test source and finished drinking water for endocrine-disrupting compounds (EDCs, beginning in 2004) and pharmaceuticals and personal care products (PPCPs, beginning in 2005) in its source water and drinking water. The Milwaukee Water Works meets EPA requirements to test for 90 regulated contaminants, and voluntarily tests for over 500 non-regulated contaminants. Most of the contaminants are not detected.

Milwaukee plays it safe to make sure our drinking water is safe and healthy. Science is evolving and as research methods are developed, more compounds are added to the testing every year. Scientific research has not proven any impact on human health at the trace levels these compounds are being discovered. Neither testing for EDCs and PPCPs nor disclosure of results from voluntary testing is required under the Safe Drinking Water Act. In Milwaukee, the monitoring is done to learn more about water quality, to be in the best position to take additional action if needed, to collect baseline data for study, to meet future regulations, and to provide full disclosure of findings to the public.

What can consumers do? The best and most cost-effective way to ensure safe water at the tap is to keep drinking water source waters clean. You can help by not flushing unused medications down the toilet or sink. Watch for local Medicine Collection Days.

Consumer information from the American Water Works Association is found on the front page of www.drinktap.org (at the left, chose Water Information.)

The Water Research Foundation in late 2008 released a report, Toxicological Relevance of Endocrine Disruptors and Pharmaceuticals in Drinking Water which found EDCs and PPCPs can occur in drinking water but at concentrations too low to pose a risk to human health. The study, which gathered samples from 17 water utilities in the United States over a three-year period, found the chemicals occur infrequently and at very low levels. The findings are available at www.prweb.com/releases/2009/03/prweb2199124.htm

In 2008, the Associated Press (AP) cited the Milwaukee Water Works as one of only 28 utilities in the U.S. to test source and treated water for emerging contaminants such as PPCPs. The AP said Milwaukee was the first U.S. utility to post the results on the Internet. The Milwaukee Water Works makes this information readily available to demonstrate a commitment to water quality and transparency in its information.

As a result of its rigorous water quality monitoring and investment in treatment and distribution systems, Milwaukee was in full compliance five years ahead of time with new EPA regulations to control disinfection byproducts.

The Milwaukee Water Works has been recognized by the EPA for its interagency relationships with local, state, and national health and environmental agencies in a program of enteric disease surveillance and response.

For more information about Milwaukee water quality, please visit the Water Quality section.

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Radon is a known cancer-causing agent that leaches from soil into groundwater. There is no radon in Milwaukee's drinking water. Our source is Lake Michigan, a surface water source, and radon is not found in surface waters.

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Source of Milwaukee water

The source of Milwaukee's water is Lake Michigan, one of the five lakes that comprise the Great Lakes. By size, it is the third largest of the Great Lakes and is the only one of the lakes that is contained entirely inside U.S. borders. Lake Michigan holds six quadrillion gallons of water. (source: Great Lakes Information Network)

Lake Michigan is the sixth largest lake in the world. The lake is approximately 307 miles long and averages 75 miles across, covering an area of 22,400 square miles. That is equal to the combined areas of the states of Maryland, Massachusetts, and Delaware. Lake Michigan has 1,638 miles of shoreline including islands.

Lake Michigan is 335 feet above Lake Ontario and 577 feet above sea level. The lake averages 279 feet in depth and reaches 925 feet at its deepest point.

The lake's drainage basin is 45,600 square miles and includes portions of Wisconsin, Illinois, Indiana, and Michigan. In Wisconsin, 30.7% of the land mass is within the Great Lakes Basin.

Lake Michigan's cul-de-sac formation means that water entering the lake circulates slowly and remains for a long time (retention) before it leaves the basin through the Straits of Mackinac. Scientists have calculated that the water in the lake replenishes over a period of 99 years.

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Home water filters

It is not necessary to use a water filter, considering Milwaukee's highly effective water treatment system that uses ozone disinfection, mixing and coagulation, biological filtration, and chloramine disinfection.

Milwaukee water quality surpasses all state and federal regulations. The U.S. Environmental Protection Agency (EPA) requires water utilities to test for 90 regulated contaminants on a regular basis. The Milwaukee Water Works goes beyond those requirements by testing for over 500 known contaminants.

Milwaukee's drinking water is rated among the highest quality in the nation.

If you choose to use a filter, identify what it is you wish to reduce/remove from the water and select a filter that will accomplish this. If you use a water filter, it is important to follow the manufacturer's instructions for regular replacement of the filter.

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Water hardness

Water is said to be hard if the minerals calcium and magnesium are in the water. The more these naturally occurring minerals are present, the harder the water is considered. It is "hard" for soap to lather or make suds.

Milwaukee's water is considered moderately hard, and water softeners are not necessary for residential use. Milwaukee water hardness can be reported in different measurements:

  • 8.01 grains per gallon
  • 137 milligrams per liter (mg/L) with a range of 6.7 to 8.5 grains per gallon

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Water treatment process

Click here for a diagram of the water treatment process (Spanish translation).

The Milwaukee Water Works treats Lake Michigan water at two plants using ozone disinfection and biological filtration treatment process with multiple-barrier protection.

The Linnwood Water Treatment Plant has 32 filters and the capacity to treat 275 million gallons of water per day. Water for the Linnwood Plant is drawn from an intake 6,565 feet from shore, five miles north of the Milwaukee harbor, at a point where Lake Michigan is 62 feet deep. The Linnwood Plant was completed in 1939.

The Howard Avenue Water Treatment Plant has eight filters and a capacity of 105 million gallons of water per day. Its intake is 11,767 feet from shore where lake water depth is 57 feet deep. The Howard Avenue Plant was completed in 1962.

Chlorine is added to the water at the two intakes. This chlorine is a minimal dose and is used to control the growth of quagga mussels inside the crib and intake tunnel.

As source water enters the first stage of water treatment, ozone is bubbled into the water from the lake in large contactor tanks. A highly reactive gas that destroys molecules with which it makes contact, ozone destroys illness-causing microorganisms and harmful compounds. It removes taste and odor compounds in the lake water, and reduces the formation of disinfection byproducts.

At the end of primary disinfection, a quenching agent is added to remove any residual ozone. The agent reacts with ozone in water to form water and oxygen. The ozone supersaturates the water with oxygen, sometimes causing the water to look cloudy. There is an ozone destruct system should any ozone rise from the water into the air space above the water in the ozone contactor basins. There is no ozone in the water when it reaches our customers. The treatment process does not release ozone from the treatment plants into the environment.

The next step is coagulation and flocculation. Aluminum sulfate (also known as alum) and polymer are added to the water to neutralize the charge on microscopic particles in the water. The water is then gently mixed to encourage the suspended particles to stick together to form floc.

Sedimentation is the process in which the floc settles out and is removed from the water.

The next step is dual media, biologically active filtration. The water is slowly filtered through 24 inches of anthracite coal and 12 inches of crushed sand in large basins to remove very small particles.

After filtration, liquid chlorine is added as a secondary disinfectant. This provides extra protection from potentially harmful microscopic organisms.

Fluoride is added to help prevent tooth decay.

A phosphorous compound is added to help control corrosion of pipes. This helps prevent lead and copper that may be present in pipes from leaching into the water.

As the water leaves the plant, ammonia is added to change the chlorine to chloramine, a disinfectant that maintains a residual in the distribution system against bacterial contamination. Fresh, pure water is delivered to your faucets.

All chemicals that are added are certified food grade, safe for use in foods.

Treated water is stored in deep underground tanks and also flows by gravity to pumping stations and into the distribution system. The distribution system consists of 1,960 miles of water mains ranging in diameter from 4" to 60". Pumping stations and re-pumping stations help maintain adequate water pressure in the system. Reservoirs, tanks, and towers are used to store water to meet demand during peak usage.

Safe, abundant drinking water is available 24 hours a day.

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