After years of planning and about nine months of construction work, the new ultrafiltration facilities at the Two Rivers water filtration plant are now in operation.

Our staff and consulting engineers have done an outstanding job of installing this new technology and equipment within the confines of our historic and attractive old waterworks buildings.

With pore openings of approximately 0.025 microns (or 0.000025 millimeter, about 1/4000th the diameter of a human hair), the new system can effectively filter out anything that Lake Michigan sends our way.

The membrane will remove 99.99% of all bacteria and viruses, and all cryptosporidium and giardia.

Chlorine is added after the water goes through the membrane to kill the remaining viruses and to protect the distribution system.

For instance, during final testing of the new filters, the water plant encountered lake water with very high turbidity (or cloudiness - likely due to flooding and runoff in recent days from heavy rain). The new filtration system performed admirably; consistent with performance data obtained during filter testing that preceded construction.

The system is designed so that all water drawn from Lake Michigan must pass through a filter membrane before it enters the city's distribution system on its way to the households and businesses. Water enters the system inside the hollow fibers and is drawn outward through the tiny filter pores into the surrounding tubes. Impurities and pathogens remain trapped inside the fibers. The clean water receives a dose of chlorine to kill any remaining viruses, and then flows out to pumps that deliver it around the city.

The filter modules are periodically cleaned by backwashing, in which water is forced from the tubes to the insides of the fibers. The backwash water carrying the impurities passes down a drain and into the city sewer system for processing at the wastewater treatment plant.

The filtering process requires no chemical or other pretreatment, except that activated carbon is added upstream from the filters to improve color and taste during times of low lake-water quality.

The initial capacity of the ultrafiltration membrane facility is 3.75 million gallons per day (mgd). The average use is 1.4 mgd with peak demand around 2.5 mgd.

Two Rivers now can claim a water supply that's guaranteed free of cryptosporidium, giardia, and other water-borne microorganisms.

Two Rivers now has a water supply that won't be susceptible to "boil water" orders for failure to meet new, tougher water standards - a water supply that will meet our community's needs for many years to come.

The new facility is easily expanded by just adding more filters rather than conducting a major building project.