Chris Nancrede Presents Chemical-Free Legionella Control Approaches at Legionella 2026 in Zurich

Legionella Control Systems founder and president Chris Nancrede, EIT, ASSE 12080, recently presented at Legionella 2026, the 11th International Conference on Legionella, held September 7–11 at the University of Zurich in Switzerland. The international conference brought together researchers, engineers, public health professionals, water treatment specialists, and other experts focused on Legionella and Legionnaires’ disease.

Chris presented before an audience that included members of the U.S. Centers for Disease Control and Prevention (CDC) and internationally recognized Legionella expert Dr. Janet Stout, highlighting his expertise alongside leading researchers and public health professionals in the field.

Chris’s presentation, “Two Chemical-Free Approaches to Controlling Legionella Growth in Building Water Systems: Dissolved Oxygen Reduction and Charged-Membrane Filtration,” examined emerging approaches to Legionella control that do not rely on adding oxidizing chemicals to building water systems.

Exploring Chemical-Free Legionella Control

Chemical treatment remains an important tool for managing Legionella in building water systems, but it can also introduce challenges such as disinfection byproducts, corrosion, monitoring requirements, and ongoing operational demands.

Chris’s presentation focused on two approaches that work differently from conventional chemical disinfection: dissolved oxygen reduction and charged-membrane filtration.

The first approach, dissolved oxygen reduction, targets the environmental conditions that allow Legionella pneumophila to survive and grow. Because L. pneumophila requires oxygen for respiration, reducing dissolved oxygen to very low levels can inhibit its ability to remain active and culturable. Research presented during the session demonstrated the potential for membrane-based dissolved oxygen removal to reduce Legionella concentrations and provide ongoing control within circulating hot water systems.

Legionella Control Systems has developed a dissolved oxygen removal system using hollow-fiber membrane technology to extract dissolved oxygen from water. The approach is designed specifically for circulating hot water systems, where Legionella growth can present a significant challenge.

The second approach discussed was point-of-entry charged-membrane filtration. Rather than controlling conditions within the building’s plumbing system, this technology works at the building entrance to reduce the amount of Legionella and other microorganisms entering the water system.

Charged-membrane filtration uses electropositive media to capture microorganisms through electrostatic attraction. Performance testing of the technology has demonstrated high levels of microbial removal, including Legionella pneumophila, under specified test conditions.

Different Technologies, Different Roles

An important theme of the presentation was that these technologies address different parts of the Legionella control challenge.

Charged-membrane filtration reduces the incoming microbial load, while dissolved oxygen reduction addresses conditions within the building water system that can support Legionella growth.

The presentation also considered how these approaches compare with other technologies, including ultraviolet (UV) treatment and conventional chemical disinfection. UV can inactivate microorganisms as they pass through the treatment system, but it does not provide a residual throughout the building’s plumbing. Similarly, point-of-entry filtration reduces what enters the building but does not provide residual control downstream.

This highlights the importance of looking at Legionella control as a layered strategy—or “defense in depth”—rather than relying on a single treatment technology.

Continuing the Conversation Around Legionella Control

Presenting at Legionella 2026 gave Chris the opportunity to share these approaches with an international audience of professionals working across engineering, water treatment, public health, and Legionella research.

For Legionella Control Systems, the presentation also reflects the company’s broader focus on engineering-based approaches to Legionella prevention, remediation, and long-term water system management.

As building owners and facility managers continue to evaluate ways to manage Legionella risk, chemical-free technologies such as dissolved oxygen reduction and charged-membrane filtration provide additional tools that can be considered as part of a comprehensive water management program.

Contact Us

Learn more about dissolved oxygen removal and charged-membrane filtration for Legionella control and work with Chris Nancrede by calling +1 888-416-8626 or using the contact form.