When David Warsinger talks about water, it’s never just about water.
It’s about thermodynamics, membranes, microbes, minerals, agriculture, geopolitics — and the quiet urgency of building systems that actually work in the real world.
Now a faculty member at Purdue University, David’s path to leading one of NAWI’s most ambitious desalination pilot projects began years earlier in an MIT conference room, crowded around a whiteboard with . What started as a “side project” during his PhD has since evolved into patented technology, multiple partnerships with startups, international research momentum — and, most recently, NAWI support to build the largest true-batch seawater reverse osmosis (RO) system ever developed.
Rethinking Desalination at Its Core
Conventional reverse osmosis desalination operates continuously: water flows in, pressure stays high, and energy is often wasted by overpressurizing the system. David and his collaborators questioned a foundational assumption — what if desalination didn’t have to be continuous at all?
Instead, they explored batch and semi-batch reverse osmosis, where pressure changes dynamically over time to closely follow the minimum pressure required to desalinate water. This subtle shift turns out to matter a lot.
But there was a catch. A true batch system requires precise, simultaneous control of both pressure and volume — something that hadn’t been solved before at scale. Through persistent whiteboard brainstorming and years of iteration, David and cracked the problem, leading to patented configurations that laid the groundwork for today’s pilot systems.
NAWI Support Enables a First-of-Its-Kind Pilot
With support from NAWI, David’s team at Purdue, Colorado School of Mines, and Oak Ridge National Lab set out to do something bold: build the largest true-batch RO pilot system in the world.
Housed on a 25-foot trailer and operating up to 40–50 gallons per minute , the system is anything but small. The membrane vessels are roughly 10 feet long, the valves are “about the size of a person’s head,” and the main pump and motor weigh nearly 180 pounds. What began as a proposal for a 10-gallon-per-minute system grew — with NAWI’s encouragement and additional resources from collaborator Tzahi Cath’s Department of Defense project — into a five-times-larger, fully modular pilot platform.
The system is designed to compare multiple desalination modes side-by-side: continuous RO, semi-batch RO, true batch RO, and other emerging configurations. It can test seawater, brackish water, high-salinity brines, and even difficult industrial and agricultural wastewaters — making it a flexible testbed for next-generation water treatment.
Beyond Energy: Scaling, and Recovery
Energy efficiency is only part of the story.
Because batch RO cycles salinity up and down every few minutes, it naturally disrupts biofilm formation, a major cause of membrane failure in conventional systems. The rapid salinity changes can cause microbial cells to swell and burst — a phenomenon David’s team has been studying in detail.
Batch operation also opens the door to higher water recovery. Traditional desalination systems avoid operating near salt saturation to prevent scaling and crystallization, which can permanently foul membranes. But batch RO can safely pass through supersaturated conditions for short periods, allowing operators to extract more water from the same feed — an especially valuable advantage for brines, groundwater, and mineral-rich streams.
Applications: Who Benefits First?
While municipal utilities tend to be slow adopters of new technology, David sees near-term impact in industry — particularly sectors that already handle difficult waters.
Critical minerals like lithium and iodine often come from salty brines that are currently concentrated using massive evaporation ponds. Batch RO could dramatically reduce land use, energy demand, and environmental impact in these processes. Agricultural wastewater, industrial reuse, and high-recovery treatment for PFAS and other emerging contaminants are also strong candidates.
Some of this impact is already happening. Variations of David’s batch-inspired designs have been adopted by startups treating animal wastewaters and agricultural flows — with systems now operating at over one million gallons per day.
Scaling Science in a Challenging Funding Landscape
Building hardware-intensive systems on accelerated timelines isn’t easy — especially in today’s uncertain research funding environment. David is candid about the challenges: short pilot timelines, the difficulty of sustaining graduate student support, and the broader consequences of delayed or canceled federal funding.
Yet the urgency only reinforces the stakes.
Water security, critical minerals, agricultural resilience, and energy efficiency are deeply interconnected. Technologies that improve desalination efficiency and recovery don’t just make water cheaper — they help secure food systems, reduce geopolitical vulnerabilities, and protect ecosystems from salinization.
Training the Next Generation
Beyond the technology itself, David is deeply invested in people. His lab has trained an unusually large number of graduate students for an early-career faculty member, many of whom have gone on to faculty roles, startups, and leadership positions in water research.
He also leads outreach efforts with K–12 students, coaches intercollegiate water and marine energy teams, and believes strongly that early exposure to water science shapes future careers.
“If people understand water early,” he says, “they care about it differently.”
Looking Ahead
With NAWI’s support, David’s team is pushing batch reverse osmosis beyond proof-of-concept toward commercialization-ready scale. The goal is simple — and ambitious:
To make desalination and water reuse less energy-intensive, more resilient, and more capable of handling the waters we can no longer afford to ignore.
What began as a whiteboard exercise is now rolling on a trailer, valves humming, membranes cycling — quietly redefining what’s possible in water treatment.
The National Alliance for Water Innovation (NAWI) NextGen Program supports the development of early-career NAWI researchers and members of the alliance to help build a domestic workforce capable of driving future research and development in the water energy sector. Early-career NAWI-affiliated scientists, including graduate students, postdoctoral researchers, and early-career staff members are encouraged to join the program!