The Milwaukee Water Works treats Lake Michigan water at the Linnwood Water Treatment Plant on the north side and the Howard Avenue Water Treatment Plant on the south side. The Linnwood intake is 1.25 miles from the shore at a depth of 60 feet. The Texas Avenue intake supplying the Howard Avenue Water Treatment Plant is 2.5 miles from shore, also at a depth of 60 feet. The lake water passes through a multiple barrier treatment process barriers to protect public health. The barriers destroy and remove illness-causing microorganisms in the lake water.
The primary form of disinfection is ozone gas. Ozone generators spark liquid oxygen, O2, with electricity to create ozone gas, O3. In the first stage of water treatment, ozone is bubbled into the water in large contactor tanks. Ozone attacks illness-causing micro-organisms and breaks apart harmful compounds at the atomic level. With its three oxygen atoms, ozone is unstable and highly reactive. It readily gives up one atom to the carbon in the membranes of microbes. Ozone destroys illness-causing microorganisms such as Cryptosporidium and Giardia. Ozone breaks apart compounds that can cause taste and odor. Using ozone as a disinfectant reduces the formation of disinfection byproducts.
Particles in the water are then removed through coagulation, flocculation, settling, and biologically active filtration.Chlorine is added as a secondary disinfectant. Fluoride is added to reduce dental cavities. A phosphorous compound is added to control pipe corrosion to prevent lead that may be present in pipes from leaching into the water. Finally, chloramine disinfection maintains a residual in the distribution system to protect against bacterial contamination. 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.
All chemicals that are added are certified food grade, safe for human consumption. The Supervisory Control and Data Acquisition System (SCADA) at both treatment plants provides real-time data from chemical feed systems, including ozone, and all water quality monitoring as well as control of water pumping stations and the distribution system. Pure, fresh water arrives at your taps.
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You can see how the Milwaukee Water Works fits into the Milwaukee freshwater cycle by visiting our exhibit at Discovery World.