Words by Patric Fransko
Trelino Evo L: The Composting Toilet That Finally Got Us to Ditch Our Cassette
There’s a particular smell that anyone who has owned a cassette toilet knows too well. It’s not just the tank itself — it’s the chemical tang that seems to work its way into the fabric of the van, the little puff of odor every time the lid opens, and the dread that builds as dump day approaches. After years of managing that routine in our own rig, we finally made the switch to a Trelino® Evo L composting toilet. We’re only a few weeks in, but the difference has been dramatic enough that it earned a permanent spot in our van, and we wanted to walk through why.
Why We Made the Switch
Our old cassette toilet did its job, technically. It held waste, it emptied at dump stations, and it worked the way it was designed to. But living with it day to day wore on us in ways we didn’t fully appreciate until we stopped dealing with them. There was always a faint chemical smell in the van — even when the cassette was freshly serviced, that blue-tinted odor seemed to linger in the cabin air. And then there was the actual dumping process: hauling the tank to a dump station, trying not to splash, and hoping the facility wasn’t a mess itself.
We’d heard from other overlanders and van lifers that composting toilets solved most of these headaches, but we were skeptical. Would it really not smell? Would it be a hassle to maintain on the road? The Evo L has answered both of those questions for us pretty definitively, and it’s changed how we think about bathroom logistics on long trips.
What the Trelino Evo L Actually Is
The Evo L is the largest model in Trelino’s Evo lineup, designed for full-time use in RVs, skoolies, and larger van builds. It’s a dry-separating toilet, which means it splits liquid and solid waste into two separate containers the moment you use it. That separation is the entire secret to why these toilets don’t smell — odor is produced when urine and solids mix together, so keeping them apart from the start prevents the reaction that causes the stink in the first place.
The unit itself is built in Germany from ABS plastic for the body and polypropylene for the waste containers, and it shows in the fit and finish. It’s available in white or dark gray, and ours has held up well to daily use with no scratches or wear marks yet. At 10.8 pounds, it’s genuinely easy to lift and move if you ever need to reposition it or pull it out for deep cleaning.
On dimensions, it’s compact enough to fit into most van bathroom footprints: 13 inches wide, 15.4 inches deep, and 16.9 inches tall. The urine canister and solids container are both 2.6 gallons. Trelino rates the urine canister for roughly 12 to 22 uses before it needs emptying, and the solids container for 11 to 20 uses, translating to an emptying cycle of about two to four days for two people using it regularly — though your mileage will vary depending on how many people are relying on it and how often you’re in the van.
Setting It Up
Installation was refreshingly simple compared to the cassette toilet plumbing we ripped out. There’s no black tank, no sewer hose, no need to tie into any existing water lines. The Evo L just sits in place — you can bolt it down if you want extra security while driving, but we keep ours in place on travel days with a tie-down strap.
One thing worth calling out: Trelino sells an optional fan accessory (the SOG fan set) that speeds up drying time in the solids container and helps with condensation, particularly useful for longer emptying cycles or if more than two people are using the toilet regularly. Installing it means drilling a hole in the unit yourself, which felt like a strange ask on a $599 toilet, but it’s a one-time, five-minute job with the right step drill bit. We haven’t installed ours yet since our cycle time has been short enough not to need it.
Living With It Day to Day
This is where the Evo L has genuinely surprised us. The seating position took a little adjustment — Trelino is upfront that men and women need to sit slightly differently for the urine separator to work as intended, and it’s worth reading their guidance rather than guessing. Once we got the hang of it, it became second nature within a couple of uses.
The bigger win has been the complete absence of smell. Not “less smell than the cassette” — actually no detectable odor, even with the lid open. We add a layer of dried coffee grounds after each use, which keeps everything dry and inert. Because the solids stay dry, you don’t need to empty the bag after every use like you would with a cassette; the bag just fills gradually until it’s time to swap it out.
Emptying is dramatically less unpleasant than the cassette routine. The urine canister pours out into any regular toilet — no dump station required. The solids bag ties off and disposes of like you would a diaper or pet waste bag, following your local regulations, which means we’re no longer tied to finding a proper RV dump station on our route. That alone has changed how we plan travel days; we’re not routing our trip around infrastructure the way we used to.
Cleaning has also been low effort. A quick wipe-down with diluted vinegar or citric acid handles the toilet surfaces, and rinsing the urine canister every couple of days keeps things fresh. There’s no deep-clean dread the way there was with the cassette’s internal tank.
The Trade-Offs
We want to be honest that this isn’t a flawless swap. At $599 for the L, it’s a real investment compared to a basic cassette toilet, though when you factor in the ongoing cost of chemical additives and the time savings on dump runs, it starts to even out over a season or two of regular use. The lid is also intentionally lightweight and not meant to be sat or stood on — Trelino is explicit about this, and it’s a small adjustment if you’re used to using a toilet lid as an occasional step stool or shelf.
You also do need to keep a supply of coconut coir or coffee grounds on hand, which is a minor addition to the packing list that a cassette toilet doesn’t require. And if you’re running the toilet hard with multiple people over several days between empties, the optional fan starts to feel less optional — budget for that accessory if your trips lean toward extended off-grid stretches.
The Verdict
A few weeks in, the Trelino Evo L has already earned its keep in our van. The elimination of chemical smell alone would have been worth the switch, but the freedom from dump stations and the genuinely simple emptying process have changed how we plan our trips. It’s not the cheapest option on the market, and there’s a short learning curve on technique, but for anyone tired of the cassette toilet routine, this is the upgrade we wish we’d made years ago.
