Water treatment company WaterSurplus has commissioned a reverse osmosis system to treat the drinking water supply of Prescott, Wisconsin, marking the company’s move into the municipal market with its ImpactRO product line. The City of Prescott, a community of about 4,730 people near the Minneapolis-St. Paul metropolitan area, selected the 580 gallon-per-minute (GPM) system to address PFAS in drinking water, nitrate and water hardness.
According to WaterSurplus, the project is among the first to use reverse osmosis in a municipal water treatment system in Wisconsin. The city worked with its consulting engineer, CBS Squared, Inc. (CBS2), to specify the installation.
Addressing PFAS, nitrate and hardness
Prescott sought a treatment solution for PFAS, nitrate and hardness in its drinking water. PFAS, a group of synthetic “forever chemicals” linked to a range of health concerns, has become a growing focus for utilities as regulators tighten limits. In 2024 the US Environmental Protection Agency set enforceable limits of 4 parts per trillion each for the compounds PFOA and PFOS, alongside limits for several other PFAS.
Reverse osmosis forces water through a semi-permeable membrane that removes dissolved contaminants, including PFAS and nitrate. WaterSurplus said the Prescott system will also remove calcium and magnesium, eliminating the need for softening salt, while iron and manganese are removed upstream using the company’s WaterPlus media filtration system. The company added that the treatment approach includes management of PFAS concentrated in the system’s reject stream.
How the system is designed to operate
WaterSurplus describes ImpactRO as a steady-state, high-recovery reverse osmosis technology. The company says the Prescott system can recover up to 90% of the water it treats and reduce membrane fouling and downtime by up to 75% compared with conventional designs. According to the company, the design draws on several features, including fouling-resistant coated membranes carrying an NSF/ANSI/CAN 61 certification, a staged feed-forward flow arrangement, intermittent cleaning bursts, adjustable recovery rates, and continuous membrane monitoring with predictive analytics.
Jim Groose, Senior Vice President of Municipal Water Treatment at WaterSurplus, said conventional reverse osmosis has often been difficult for municipalities to justify because older systems wasted 20 to 30% of the water they treated, while newer high-recovery designs were energy-intensive and complex to operate. He said the company’s approach was intended to lower operating costs and simplify operation.
Reverse osmosis in municipal supply
Reverse osmosis is widely used in desalination and industrial water treatment but has historically been less common in municipal drinking-water systems because of its energy use and the volume of water rejected during treatment. Interest is growing as utilities face stricter contaminant limits and look for ways to remove PFAS and other dissolved pollutants.
WaterSurplus, based in Loves Park, Illinois, was founded in 1989 and works on reverse osmosis systems, membrane elements, PFAS treatment and filtration. The company is a wholly owned subsidiary of Hawkins, Inc. (Nasdaq: HWKN). Further information is available at watersurplus.com.
Frequently asked questions
What is the ImpactRO system installed in Prescott, Wisconsin?
A 580 GPM reverse osmosis water treatment system commissioned by WaterSurplus to treat the City of Prescott’s drinking water supply.
What contaminants is the system designed to remove?
PFAS, nitrate and hardness (calcium and magnesium), with iron and manganese removed upstream by media filtration.
How much water does the system recover?
WaterSurplus reports the system can recover up to 90% of the water it treats.
Why is the project notable?
It is among the first municipal reverse osmosis drinking-water systems in Wisconsin.
