Public Works Department

Water Treatment &
Distribution Services
935 5th Ave SE
Minneapolis, MN 55414

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Understanding the Ultrafiltration Process

Cutting-edge technology brings cleaner water to the city

Our ultrafiltration water plant, located in Columbia Heights, is a state-of-the-art facility making Minneapolis tap water clean and safe without affecting taste.This water purification method allow us to produce up to 70 million gallons of Mississippi River water per day, removing particles so small that a standard microscope can’t detect them. We remove impurities more effectively than even federal drinking water standards require.

The City’s new Ultrafiltration Plant at Columbia Heights uses state-of-the-art technology to provide cleaner water to Minneapolis. 

A lot of water from some tiny fibers

The ultrafiltration water process uses hollow fibers to take particulate matter out of the water. The walls of the fibers are porous, letting water through and keeping the particles behind. While the fibers are tiny, there are plenty of them. Nearly 9,600 fibers are packed in one vessel with four vessels in one long module. The plant has 28 vessels on each ultrafiltration unit, and there are 40 of those units in the plant. There are about 43,008,000 fibers cleaning the city’s water. The fibers combined create a surface area of 1,669,000 square feet. If put end-to-end, these fibers would stretch more than 40,000 miles, or about 1.6 times the earth’s circumference at the equator.

Impurities as small as 0.03 micrometer (µm) is filtered out of the water you drink. The thickness of a U.S. dollar bill, red blood cells, and tobacco smoke are larger than the tiny holes in the fibers. Ultrafiltration removes nearly all viruses from the water supply; however, a fraction of them cannot be completely screened out. The threats posed by these pathogens unable to be filtered are mitigated by chlorine treatment. Dissolved salts and minerals are small enough to remain in the water after ultrafiltration. These compounds are desirable, since they contribute to the taste of our water. The natural minerals in the water create water stability, to prevent pipe corrosion which otherwise could jeopardize the water quality for customers.

One of 40 high-tech fiber filtration units at the new Columbia Heights Ultrafiltration Plant


Ultrafiltration Plant will remove microns as small as 0.03 micrometers (µm)



A cross section of an ultrafiltration module shows the thousands of hollow fibers packed inside.


Last updated Oct 6, 2016