The Milwaukee Water Works will turn off ozone treatment — the primary water disinfection process — at its Linnwood plant on the lakefront for up to 12 weeks beginning Wednesday, officials said.

All other treatment steps, including chlorine disinfection and deep coal and sand filters, will remain in use at Linnwood while a contractor completes installation of pipes and valves as part of $1.8 million worth of plant improvements that were not done when the ozone process was built there in the mid-1990s.

Water from the Linnwood plant will be safe to drink and use in the interim, officials said.

The new pipes and valves will enable plant operators to bypass the ozone treatment step for repairs or maintenance, Water Works Superintendent Carrie Lewis said. Operators currently would need to shut down the plant to make repairs to the ozone process.

Water from Lake Michigan is pumped directly into the ozone building, where the gas bubbles up through the water and kills disease-causing microorganisms.

Use of ozone also helps neutralize taste and odors typical of lake water, so consumers receiving water from the Linnwood plant might notice a change in the next 12 weeks, officials said. Water from Linnwood generally is distributed north of State St. in the service area.

After this first step in the process, the water flows into the plant, where the volume is split into two separate and parallel channels as it moves through the remaining conventional treatment steps.

Installation of pipes and valves around one side of the ozone building was completed last fall under the contract, Lewis said. This could be described as building one arm of an uppercase letter Y, she said. It was not necessary to shut off ozone treatment at that time.

In the next three months, the contractor will install pipes and valves around the other side of the ozone building, or the second arm of the Y.

Ozone replaced chlorine as the primary disinfectant at both the Linnwood and Howard Ave. water treatment plants in 1998.

It was added in the wake of the 1993 Cryptosporidiosis epidemic in Milwaukee, the largest documented waterborne disease outbreak in U.S. history.

The epidemic caused the deaths of at least 69 people in the Milwaukee area. An estimated 403,000 people in the five-county metropolitan area were sickened with watery diarrhea between late March and early April of that year.

Ozone treatment is not required by federal or state drinking water regulations. Use of chlorine alone will provide sufficient disinfection to meet water quality standards, Water Works and city Health Department officials said in a statement.

While chlorine does not kill Cryptosporidium, ozone was not the only safeguard against the parasite added in the mid-1990s.

The city invested $89 million at the time to upgrade filters, provide ozone treatment and install particle detectors at both plants. The detectors provide minute-by-minute counts of anything floating in filtered water. Those counters would indicate the presence of Crypto.

Extending the Howard Ave. plant’s water intake pipe an additional 4,200 feet out into Lake Michigan was the first major safeguard. The extra pipe moved the intake away from the plume of soil and contaminants flowing out of the Milwaukee River and harbor and south along the shoreline.

All of the safeguards together should assure consumers the water is safe to drink even in the temporary absence of ozone treatment, said Paul Biedrzycki, director of disease control and environmental health for the city Health Department.

The Water Works and Health Department monitor drinking water quality at both plants to protect public health. The two departments also review treatment plant operations and test water samples during plant improvement projects, Health Commissioner Bevan Baker said.

“Milwaukee continues to have consistently high standards for drinking water, and has some of the safest drinking water in the nation,” Baker said.

Howard Ave. plant operators will continue using ozone there during the Linnwood plant upgrade.