Known for their robust design and sustainable waste management, these toilets ditch water and chemicals in favour of a natural composting process that’s perfect for Kiwi off-gridders who care about the planet and practicality. In this review, we’ll unpack everything you need to know: the standout features, how they perform, and their eco-credentials. Whether you’re living solo or hosting a full house, let’s see if Sun-Mar™ is your off-grid match!
Key Features: What Sets Sun-Mar™ Apart
Sun-Mar™ toilets come loaded with features that make them a top contender for off-grid sanitation. Here’s the full rundown:
Bio-Drum™ Technology: This is the star of the show—a patented rotating drum inside the toilet that you turn by hand. It mixes waste with oxygen and bulking agent (like wood shavings), speeding up decomposition. Unlike simpler systems that just let waste sit, the Bio-Drum™ actively works to break it down faster.
Waterless (or Nearly So): The Excel and Centrex AirFlow models use zero water, saving you thousands of litres annually—an absolute win if you’re relying on rainwater tanks. For those who like a flush, the Centrex MicroFlush uses just 0.2 liters per flush (compare that to 4–9 liters for a standard toilet), making it a water-saving champ.
Odour Control: A small electric fan (35 watts for 240 models, 1.9 watts for non-electric) pulls air through a vent stack, whisking away smells before they can linger. Users consistently report fresh bathrooms, even with heavy use!
Big Capacity: The Excel 240 handles 3–4 full-time users (or 6–7 part-time, like weekenders), while the Centrex can achieve up to 6–7 full-time users. That’s ideal for families, group retreats, or even small eco-communities—no one’s left waiting.
Power Options for Flexibility: Electric models (Excel 240 and Centrex 240) run on 240 volts for faster drying, perfect if you’ve got reliable power. Off-grid? The non-electric versions (Excel NE and Centrex NE) use passive venting or a 12-volt fan powered by solar—great for remote setups.
Two-Stage Composting: Waste breaks down in the Bio-Drum™, then moves to a finishing drawer for the final stage. The result? Safe, usable compost you can pull out without a mess—ready to enrich your garden after some curing.
Compliant with New Zealand Building Standards: Both models meet AS/NZS 1546.2:2008 and NSF/ANSI-41 standards, proving they’re efficient in New Zealand’s conditions and built to handle consistent use without faltering.
Design: Durable and Practical
Sun-Mar™ toilets are built to last and look good doing it. Here’s what you’re working with:
Excel: This is a self-contained, on-floor unit that sits directly in your bathroom, with a glossy white exterior that looks good and is easy to keep clean. It’s a fairly substantial piece of kit, designed for serious off-gridders who value reliability. Inside, the Bio-Drum™ is housed within a robust shell made from a combination of fibreglass and vacuum-moulded components, built to handle years of regular use in demanding environments.
Centrex: This split-system design is a bit different—the composting tank lives below the floor (say, in a basement or crawlspace), and only a sleek pedestal sits upstairs. It’s ideal for larger homes where you want big capacity without cluttering the bathroom, and where sub-floor space is available.
Build Quality: Both models are tough as nails, with corrosion-resistant materials that stand up to humid Kiwi climates. The design is user-friendly—spin the drum, vent the air, and empty when ready. They’re not just functional; they’ve got a polished vibe that fits modern off-grid homes.
Performance: Odour-Free and Ready for a Crowd
When it comes to how these toilets hold up, Sun-Mar™ delivers the goods:
No Smells, No Worries: The Bio-Drum™ keeps waste aerated, and the fan pulls odours out through the vent. Whether it’s the Excel with 3–4 full-time users or the Centrex with up to 7, the system stays fresh.
High Capacity: The Excel can go weeks between empties for a small household (once every couple months for part-time use), while the Centrex™ is typically emptied once or twice a year in holiday homes with bigger crews. That’s a huge relief if you hate frequent maintenance.
Flush Option: The Centrex MicroFlush adds a familiar flush feel with almost no water, and it still composts like a pro. It’s a nice middle ground if you’re easing into waterless living.
Real-World Proof: Certified for odourless operation at max capacity, these toilets handle busy scenarios without breaking a sweat. Think family gatherings or eco-lodge guests—Sun-Mar™ keeps up, no problem.
Environmental Benefits: Green Living, Kiwi Style
For anyone passionate about sustainability (and New Zealanders tend to be), Sun-Mar™ checks all the boxes:
Water Savings: Waterless models eliminate usage entirely, while the MicroFlush cuts it down to a fraction of standard toilets. In a country where water conservation matters, this is a big deal.
Nutrient Recycling: The compost you get is chemical-free and garden-ready after curing—perfect for growing decorative gardens or trees. It’s a closed-loop system that turns waste into a resource.
Low Energy: Non-electric models use 1.9 watts for the fan, and even electric (heated) models sip just 3 kWh/day—barely a blip on your power setup.
No Pollution: No blackwater, no chemicals—just a clean process that aligns with NZ’s eco-conscious values. It’s off-grid sanitation you can feel proud of.
Maintenance: Simple and Straightforward
Keeping a Sun-Mar™ running is low-effort and fuss-free. Here’s the full scoop:
Daily: Add a scoop of bulking agent per person, spin the Bio-Drum™ a few times to mix, and you’re done. Toilet paper goes in—no need to separate it.
Periodic: Empty the compost drawer every few weeks for full-time use, or once every few months for part-timers. The Centrex tray might only need emptying once or twice a year, even with bigger groups.
Installation: Both models need floor space for the pedestal, a vent pipe that extends at lease 0.6m above the roof as per NZ regs, and a small sub-strata leachate drain for excess liquids. The Centrex requires accessible sub-floor space, making it ideal for basements or raised buildings.
Use Cases: Where Sun-Mar™ Thrives in NZ
Tiny Homes & Cabins: The Excel is great for concrete slabs and on-floor installs, while the Centrex suits homes with a bit more room below. Both save water and manage waste efficiently.
Holiday Homes: The Centrex shines for groups (up to 7 full-time users), and the Excel is great for smaller crews or couples who want low upkeep.
Vanlife: While the Excel and Centrex aren't suitable for mobile applications, Sun-Mar’s™ GTG model is a vanlife rockstar (a story for another day!).
Eco-Communities & Lodges: The Centrex handles shared setups or eco-tourism with its high capacity and compost output—perfect for sustainable living hubs.
The Verdict: Is Sun-Mar™ Right for You?
The Sun-Mar™ Excel and Centrex composting toilets are powerhouse solutions for off-grid Kiwis who need capacity, reliability, and a green edge. They cost more upfront than more basic systems, but you get less maintenance, bigger loads, and years of dependable performance in return. It’s sustainable sanitation that feels right at home in New Zealand. Ready to make the leap? This could be your ticket to hassle-free, eco-friendly living!
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