Reverse osmosis membranes rarely die from salt
Biofouling is a biology problem, and Nature always finds a way...
GREG REYNEKE / WATER QUALITY IMPROVEMENT PROFESSIONAL
A clearer understanding of water.
I’m Greg Reyneke. I write about water quality, treatment, and the questions that connect water science to everyday life.
Greg’s posts on Substack
San Jose - Safe but Hard water
it’s OK to help your customers close the loop...
The confidence gap
imposter syndrome and its mirror twin in the water trade
More of Greg’s Articles
General
Chlorine in Municipal Drinking Water
When chlorine (or chloramine) reacts with natural organic matter in source water, it forms hundreds of DBPs, primarily trihalomethanes (THMs, e.g., chloroform) and haloacetic acids (HAAs). Hundreds of additional DBPs exist and are not…
General
Apple Cider Vinegar Hair Rinse in Hard Water Areas
An apple cider vinegar (ACV) rinse is a reasonable periodic add-on when you wash hair in very hard water. It is not a substitute for a water softener or a true chelating shampoo. The useful effects come from acidity, not from any special…
Corrosion
Softeners don't hurt water heaters
The most common driver of accelerated anode consumption is elevated electrical conductivity in the water, not the mere presence of sodium ions (or the absence of Calcium). I have been solving corrosion problems for three decades, from…
General
Watering plants with softened water?
Ion exchange trades calcium and magnesium for sodium (or potassium) on an equivalent basis. The resin does not know or care whether the water started at 5 or 55 grains per gallon. It swaps one equivalent of hardness for one equivalent of…
General
Membrane scaling calculations
Scaling is what happens when a sparingly soluble salt exceeds its capacity to stay dissolved and precipitates out onto whatever surface is nearby: a membrane, a heat exchanger tube, the inside of a boiler, the element in a water heater…
General
Water can undermine your metabolism
Your water supply is either supporting your metabolic health or quietly undermining it. Most people think about insulin resistance in terms of what they eat and how much they move. Those things matter enormously, but there’s a third…
General
Bacteria in your well water
General
Your gloves are telling you lies
The microplastics story is a particularly clean illustration of something I think about constantly: the act of measurement changes what you’re measuring. Every time a sample is collected, handled, transferred, stored, processed, and…
General
Are PFAS really "Forever" Chemicals?
The problem is that policy built on rhetorical shortcuts tends to produce blunt instruments. And when the instruments are blunt and the underlying science is nuanced, the compliance burden falls indiscriminately while actual risk reduction…
General
EPA's RealWaterTA Initiative
Technical assistance (TA) under RealWaterTA is a targeted, boots-on-the-ground effort to help water systems thrive. The EPA is refocusing on eight core priorities to ensure long-term reliability in providing safe drinking water and…
General
Health on tap
The future of drinking water is not a conflict between centralized and decentralized; it never should have been. It’s really a hybrid model: Utility infrastructure to supply water as cost-effectively as possible + Certified POU/POE…
General
TFA - is the risk real?
TFAs are here forever. Short term risks seem minimal. The long-term picture is murkier and more concerning. TFA's extreme persistence (no natural degradation in terminal sinks like oceans or deep aquifers) means accumulation is effectively…
General
Rethinking Forever Chemicals
While the phrase “forever chemicals” captures attention, it does not accurately reflect the chemical diversity or biochemical behavior of PFAS as a class. The phrase succeeded in raising awareness. But the future of PFAS management belongs…
General
Richard Mest joins WQA
Richard Mest has joined the Water Quality Association as Strategic Affairs Officer. In the newly created role, Mest will serve as a mentor and catalyst for strategic affairs across the association, but most specifically WQA’s business…
General
Smart Cities with Dumb Water
News
EPA to keep MCLs for PFOA, PFOS
EPA is announcing its intent to extend compliance deadlines for PFOA and PFOS, establish a federal exemption framework, and initiate enhanced outreach to water systems, especially in rural and small communities, through EPA’s new PFAS…
News
WQA selects Phoenix for 2027 Convention & Expo
The 2027 WQA Convention & Expo will be held in Phoenix, AZ. This signature event is expected to bring more than 3,000 dealers, manufacturers and consultants from around the world to the fifth-largest U.S. city April 28-30, 2027…
General
April 2025 EPA moves to combat PFAS in ethe environment
With this approach, EPA will provide the foundation and investment necessary for a toolbox that will help states and communities dealing with PFAS contamination…
Opinions
2027 EU Harmonization Impact
The 2027 EU Harmonization represents more than just a regulatory shift—it’s a call to action for the water filtration industry to evolve. By prioritizing health, transparency, and sustainability, the new rules will not only protect…
General
April 2025 Pentair Pricing
Pentair has assessed the cost impact of the United States’ recent tariff increases on goods imported from multiple countries. These impacts include finished goods as well as raw materials. As a result, Pentair will be implementing three…