Corrosion rarely announces itself as a "big water problem." It shows up as leaching at the tap, residual loss in the field, premature equipment replacement, and the slow, expensive erosion of decision-quality.

Pat Rosenstiel (CEO) and Wolf Merker (chemist/Chief Science Officer) of Great Water Tech lay out a system-wide view of corrosion control—starting with what changed in Flint from a technical standpoint and moving into why many utilities still struggle to meet expectations when standards and risk assumptions shift.

System-wide corrosion control starts with chemistry and consequences

A source-water change can shift corrosivity fast. If corrosion control does not adjust proactively, the downstream effects show in metal release and public exposure. Wolf stresses the distinction between the technical problem and the political challenges, then points to corrosion control as a solvable technical matter when it is treated as a system condition—not a single asset issue.

Why "phosphate-only" isn't the end of the story

Trace frames what most operators recognize: many municipalities use phosphate inhibitors to form a tenacious film and reduce corrosion. Wolf argues phosphates are "a little bit of old news" in practice and explains the approach Great Water Tech discusses with their German partners—using phosphates and silicates together in the right amounts to create a tighter separation between water and metal.

Barriers, biology, and the disinfection tradeoff

Wolf breaks corrosion drivers into three sources: chemical, biological, and electrochemical (dissimilar metal corrosion). He also ties corrosion to cascading operational decisions—especially disinfectant strategy. If residual loss pushes a system from chlorine to chloramine, Wolf warns that corrosivity can increase dramatically, and that corrosion can amplify the formation of disinfection byproducts as chlorine reacts with what is in the water.

What industrial water treaters should listen for

Pat connects the same barrier logic to industrial priorities—CapEx, OpEx, and lifecycle extension in closed systems (cooling towers, closed chilled loops, boilers). Wolf clarifies that closed systems require different product "flavors," while keeping the core concept consistent: the combined silicate/phosphate approach remains the best path he is aware of.

Listen to the full conversation above. Explore related episodes below. Stay engaged, keep learning, and continue scaling up your knowledge!

Timestamps

02:20 - Trace sets the tone for the episode: decision-quality improves when you "rethink the way that you think you know things," especially around tests and procedures

08:20 - Words of Water with James McDonald

11:00 - Upcoming Events for Water Treatment Professionals

18:22 - Interview with Pat Rosenstiel, CEO of Great Water Tech & Wolf Merker, Chief Science Officer of Great Water Tech

23:00 - Flint technical breakdown

27:30 - Corrosion control options

32:20 - Scale vs. Corrosion

43:40 – Algae Control Pivot

Connect with Pat Rosenstiel

Website: Great Water Tech | Water Treatment Solutions

LinkedIn: https://www.linkedin.com/in/pat-rosenstiel-a148952/

Great Water Tech LLC: Overview | LinkedIn

Connect with Wolf Merker

Website: Great Water Tech | Water Treatment Solutions

LinkedIn: https://www.linkedin.com/in/wolf-merker-a1b95284/

Great Water Tech LLC: Overview | LinkedIn

Guest Resources Mentioned

NSF/ANSI/CAN 60 — Drinking Water Treatment Chemicals: Health Effect

NSF — Drinking Water Treatment Chemicals Certification (NSF/ANSI/CAN 60) (how certification works)

ANSI Webstore listing (official standard access/purchase)

EPA — Lead and Copper Rule (regulation hub)

EPA — Lead and Copper Rule Improvements (LCRI) (final rule page)

EPA fact sheet — Tap Monitoring Requirements (LCRI) (sampling protocol changes)

Great Water Tech

Folmar (Great Water Tech) — corrosion inhibitor (phosphate + silicate blend)

Algae Armor (Great Water Tech) — nutrient-binding tool for ponds/lakes

EPA Distribution System Toolbox — Pigging fact sheet (PDF) (removing biofilm/scale/sediment from mains)

U.S. Bureau of Reclamation report page (chlorine vs chloramine impacts incl. corrosion/leaching discussion)

AWWA Opflow article (main cleaning techniques incl. pigging): AWWA's utility-facing perspective on cleaning options

Silicate corrosion inhibitors

Historical context for silicate–phosphate combinations

Scaling UP! H2O Resources Mentioned

AWT (Association of Water Technologies)

AWT Technical Training (March 2026)

Scaling UP! H2O Academy video courses

Submit a Show Idea

The Rising Tide Mastermind

Ep 422 Inside the Association of Water Technologies with John Caloritis

Hach Water Analysis Handbook

Words of Water with James McDonald

Today's definition is the smallest functional unit of a cooling tower that contains its own heat exchange section, fan or air-moving system, water distribution system, and drift eliminators.

2026 Events for Water Professionals

Check out our Scaling UP! H2O Events Calendar where we've listed every event Water Treaters should be aware of by clicking HERE.