Reverse osmosis has run on essentially the same membrane for more than forty years, and it isn’t because nobody built a better one. Nala Membranes did. It’s a sulfonated polysulfone film that shrugs off chlorine where today’s polyamide membranes come apart, and that one property kills the biofouling that quietly eats about a quarter of a desalination plant’s operating cost. A major membrane manufacturer’s engineers looked at the chemistry, liked it, and their business side said no. So the question I actually wanted to answer isn’t whether the technology works, because it does. It’s whether a company that has raised $15.15 million, roughly a sixth of what ZwitterCo banked, can get a genuinely new material adopted in a market with three or four serious players that hasn’t changed its core material in two generations.

And I’m going somewhere with this, because the honest answer runs through the least glamorous corner of the water business and past at least one fresh grave.

What did Nala Membranes actually invent?

Nala Membranes is a North Carolina startup built on polymer-chemistry work from Virginia Tech and the University of Texas at Austin, co-founded by CEO Sue Mecham and Dr. Judy Riffle, and what it has made is the first new reverse osmosis membrane material in over forty years: a sulfonated polysulfone thin film composite.

Let me unpack that, because “thin film composite” (TFC) is doing a lot of work. Every modern RO membrane is a sandwich, and the slice that actually rejects the salt is a wafer-thin polymer layer laid on top of a support. Since the late 1970s that layer has been a polyamide, and polyamide has two well-known weaknesses: its surface is rough, so gunk sticks to it, and chlorine tears it apart, so you can’t use the cheapest, most obvious tool in water treatment to keep it clean. Before polyamide, the industry ran on cellulose acetate, which was smooth and could tolerate a bit of chlorine, but it lost the flux-and-rejection race and got displaced. Nala’s pitch is that it brought both of those old virtues back, with a new material and a new way of making it.

The smooth surface is the part chemists get excited about, because it comes from the manufacturing process, not from a coating you add on afterward. Nala makes its polymer first and then lays it down, where polyamide is grown in place on the membrane in a reaction that leaves behind a rough finish and a couple of nasty waste streams. Same trick the cellulose acetate people had, brought forward to a modern high-performance film.

The chlorine advantage, and the 24% it targets

Here’s the money question, because a chemistry curiosity only becomes an investable company when it changes a number on an operator’s spreadsheet, and for RO that number is biofouling. Biofouling is just bacteria setting up house on the membrane, and the standard, boring, cheap way to stop bacteria in water is chlorine. Polyamide can’t take it, so operators fight fouling with pre-treatment, downtime, and expensive cleaning cycles instead. Nala can take it, down at drinking-water doses to keep bugs from growing, and all the way up to 10,000 ppm of hypochlorite when a membrane is genuinely filthy.

There’s an old rule of thumb in this industry that if you’re not at least 20% better than the incumbent, you don’t get a seat at the table. Sue’s answer clears that bar, and she is careful to source it rather than round it up:

That’s an operating-cost story, which matters, because in most industrial water deals the argument long ago stopped being about the sticker price of the membrane and became about what it costs you to run the thing over its life. A membrane you can chlorine-clean instead of babysit is worth more every single year, not just on day one.

Why did the membrane giants pass on it?

This is the part that gives the episode its title, and it’s more instructive than the usual founder war story. Around 2010 and 2011, before Nala even existed, the underlying sulfonated polysulfone chemistry landed on the desk of one of the big membrane manufacturers. Their technical people ran tests and liked what they saw.

Now, my instinct when I hear “the giant turned it down” is to reach for the hall of fame of corporate blindness, and the episode does exactly that: Kodak sitting on the digital camera its own engineer built, Blockbuster waving Netflix through, Xerox letting personal computing walk out the door. The trouble is that this is survivor bias dressed up as destiny. Internet Explorer held nearly 96% of the browser market in the early 2000s while being nobody’s favorite browser. Betamax was better than VHS and lost anyway. We still type on QWERTY keyboards that were designed to slow us down. Incumbency is a moat, not an accident, and the academic read is that you need to reach somewhere between 15% and 30% market penetration before adoption becomes self-sustaining. Sue puts the same wall in plainer terms: on the membrane side, she says, people can’t even fathom what you mean by a new membrane, because it’s been so long since they had one. I’ve argued this at length in a newsletter on why your water tech is probably not as disruptive as your pitch deck claims, and if that debate is your kind of fun, my newsletter is where I keep having it.

Has anyone ever actually disrupted water tech?

Yes, but you can almost count the clean examples on one hand, and every one of them took a decade or three. These are the cases I keep reaching for on the show. Trojan started in 1977 as three people in Canada betting that ultraviolet light could replace chlorine for disinfection, and most of the industry laughed until UV became mainstream municipal practice in the 2000s. The pressure exchanger, the device that recovers up to 60% of the energy in a desalination plant, arrived in 1992 and didn’t become standard until the mid-2010s, by which point something like 70 million people were drinking water that had passed through one. And the canonical case is Andrew Benedek pushing the membrane bioreactor through the 1980s and 1990s while everyone told him membranes had no place in wastewater, right up until GE bought Zenon in 2006 and the idea became obvious.

So the material working is the easy part. The pattern in this sector is that a better mousetrap wins a niche first and the mainstream last, if ever. Even today, polymer membranes hold about 93% of the market against roughly 7% for ceramics, a 2025 Global Water Intelligence split I chewed over in my newsletter, and that gap has barely moved despite ceramics being genuinely excellent. Membranes, it turns out, don’t much like a winner-take-all story.

How does Nala’s $15 million stack up against the field?

This is where I get to plug in my own numbers, because I keep a section of my Leviathan database on exactly this cohort, the startups trying to move the membrane itself, and laid side by side they tell a story the pitch decks don’t.

Look at what most of that money is actually buying. ZwitterCo, which has raised close to six times what Nala has, puts a clever zwitterionic layer on top of a polyamide. Aqua Membranes, whose 3D-printed spacers I covered with Craig Beckman, improves the plumbing around the membrane. Evove, which I looked at through its lithium work, coats and prints. Nearly the whole field is innovating around the polyamide rather than replacing it, which is the rational thing to do, because replacing the material is the hardest possible version of this game. The one team that took a swing as deep as Nala’s, Aquaporin, built biomimetic membranes out of actual water-channel proteins, raised nearly $25 million doing it, and is now dead. That’s the company Nala keeps, and it’s worth sitting with before you get too excited about a founder claiming to have out-chemistried an entire industry on $15 million.

Can a bootstrapped startup out-patient the oligopoly?

I think the interesting answer is that Nala isn’t trying to beat the giants at all, and that’s precisely why it might work. Run it through the framework I use for this: a water tech can be disruptive on four fronts, creating a market, improving performance, cutting costs, or improving the user experience, and the earlier you are, the fewer of those you’re allowed to touch at once. Nala touches exactly two. It improves performance, by handling organics and chlorine that choke polyamide, and it cuts costs, by that 24%. Two, which is the ceiling I’d give a company this young. It is not also trying to invent a new market or reinvent how plants are operated, and that discipline shows up in the fundraising.

The go-to-market matches the money. Nala is starting in industrial wastewater, the semiconductor, textile, and mining streams that are loaded with the organics polyamide hates, where a customer feels the pain sharply enough to try something new, and where you don’t need to dislodge a giant to win the job. Manufacturing is deliberately asset-light: Nala makes its own polymer, coats a sourced substrate, and hands the sheet to a contractor to roll into modules, with, as Sue points out, no waste streams to dispose of at the end. It’s a company built to survive the twenty-year adoption clock rather than to sprint at it. There’s an exit shimmering somewhere out there too, and I’ll admit I floated the idea on the show that a private-equity-owned membrane major might one day want Nala as the premium “sparkle” on a commodity product, though that one is my speculation, not a plan on anyone’s desk.

Frequently asked questions

What is Nala Membranes?

A North Carolina startup, co-founded by CEO Sue Mecham and Dr. Judy Riffle, that has developed the first new reverse osmosis membrane material in over 40 years, a sulfonated polysulfone thin film composite.

What is a sulfonated polysulfone membrane?

A reverse osmosis membrane whose salt-rejecting layer is made from sulfonated polysulfone rather than the industry-standard polyamide. It has a smoother, more chlorine-tolerant surface, which reduces biofouling and allows aggressive chlorine cleaning.

Is Nala’s membrane really chlorine-tolerant?

Yes. Nala reports tolerance from drinking-water-level doses up to 10,000 ppm of sodium hypochlorite for cleaning, where standard polyamide membranes degrade on contact with chlorine.

How much has Nala Membranes raised?

About $15.15 million across five disclosed rounds, according to the Leviathan funding database, with a further roughly $5 million priced round open at the time of the interview.

How is Nala different from ZwitterCo or Aqua Membranes?

ZwitterCo coats a zwitterionic layer onto polyamide and Aqua Membranes prints spacers around existing membranes; both improve the incumbent. Nala replaces the separating material itself.

The one thing I’d watch

If you want to know whether this is the rare water-tech disruption that sticks, don’t watch the chemistry, which already works, and don’t watch the funding headline. Watch for two things: real, paid industrial-wastewater installations that survive a full cleaning season, and a strategic lead investor writing the check that says a serious player wants this material to exist. Get those, and the twenty-year clock starts running in Nala’s favor. As Sue puts it, the whole point is to make reverse osmosis cheaper and simpler so it can do what it’s supposed to do, and that’s a fight worth losing sleep over. The full conversation, chlorine chemistry and all, is the episode.

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