history

In 1984, Dick Koenhen founded X-Flow, later joined by colleague Lute Broens from the University of Twente. Together, they revolutionized microfiltration membranes. 

Unlike the prevailing hydrophobic membranes, X-Flow introduced a hydrophilic alternative, embracing water instead of repelling it. This groundbreaking shift, developed in collaboration with the University of Twente, marked the beginning of X-Flow's commitment to innovation. 

In 1993, a pivotal event reshaped X-Flow's direction. Milwaukee, Wisconsin, experienced a devastating waterborne outbreak caused by Cryptosporidium Parvum ('Crypto'), affecting over 400,000 people and claiming 100 lives. This crisis spurred stricter drinking water regulations.

Amidst adversity, X-Flow saw an opportunity to innovate. The increased focus on water purification created a demand for advanced membrane technology. This moment marked the start of X-Flow's transformative journey, addressing the urgent need for innovative water purification solutions.

Leushuis Projects & Engineering, specialized in liquid flow process systems, had acquired X-Flow shares, the two companies cooperated closely in the development and manufacturing of membrane products for different applications, notably a better and cleaner solution.

In 1997, Norit purchased Leushuis as a strategic add-on to their activated carbon business. At the time of the acquisition, Leushuis owned about 80 percent of X-Flow. Norit and X-Flow were a perfect match, as activated carbon and membranes both play important parts in the water, food & beverage and pharmaceutical industries. Later that same year, Norit became the sole shareholder in X-Flow BV.

Pentair X-Flow - Norit belongs to the history of our company


With customers in more than 150 countries, Norit had developed into a multinational company with a strong focus on innovation. As a membrane manufacturer, X-Flow became part of the Clean Process Technologies (CPT) division of Norit Holding B.V.

In 2000, Norit acquired STORK membranes and integrated STORK’s membrane portfolio in the X-Flow product range.

In 2011, Global Water Intelligence selected Norit as Water Technology Company of the Year. Norit had been nominated for breathing new life into activated carbon, a proven technology for more than a century, and for taking the new technology of ultrafiltration further than ever before.


In May 2011, Pentair Inc. (founded in 1966) acquired X-Flow. Pentair is a global diversified industrial company headquartered in Minneapolis, USA.

With X-Flow, Pentair is todays world’s leading ultrafiltration membrane manufacturer. X-Flow membrane elements are found in processing installations all over the world and virtually every landmark industrial project with membrane technology, either installed in Original Equipment Manufacturer (OEM) systems, or in Pentair’s own systems and solutions.

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Ootmarsum, The Netherlands

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