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View ProductThe Biolan Simplett (70570210) is a waterless, urine-diverting composting toilet designed for cottages, cabins, and off-grid or seasonal homes. This in-depth review explains how it works, how it performs in real-world conditions, and where it makes sense as a low-water, low-impact toilet solution.
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By Rise
Jan 31, 2026 · 28 min read
The Biolan Simplett is a compact, waterless composting toilet that uses urine diversion and passive ventilation to reduce odors and moisture. It suits cottages, cabins, and off-grid or seasonal homes with light to moderate use, as long as owners are comfortable with hands-on maintenance and managing organic waste responsibly.
If you are planning a new cottage, renovating a rustic cabin, or finishing an off-grid bunkie, a full flush toilet and septic system may be more than you need or want to pay for. The Biolan Simplett composting toilet offers a compact, waterless alternative that can be installed in small spaces with basic tools and a vertical vent. Before you place one in your bathroom design or bunkie layout, it is important to understand how it works in day-to-day use, what ongoing maintenance it requires, and whether its capacity and performance match your family’s or guests’ habits.
The Biolan Simplett (model 70570210) is a dry, waterless toilet that combines urine diversion and on-site composting of solid waste. Instead of flushing with water to a septic or sewer system, the Simplett collects solids in a removable container and routes urine separately to reduce moisture and odor in the solids chamber. A vertical vent pipe moves air upward and out of the building, helping to control smells and support drying and composting processes.
This approach is designed to minimize water demand and reduce the load on septic systems or eliminate them entirely in some low-use, code-compliant situations. However, it also shifts more responsibility for waste handling and system performance onto the owner or caretaker.
The core of the Simplett’s design is its separation of liquids and solids, supported by adequate ventilation and the addition of dry, carbon-rich bulking materials. Together, these features aim to reduce odors, lower moisture levels, and create conditions that can support composting after the waste leaves the toilet housing.
At the front of the Simplett bowl, a molded channel captures urine and other liquids. These liquids are directed through a hose to a separate container or drain line, depending on your installation and local regulations. The goal is to keep most of the moisture out of the solids container so that the material inside stays drier and less prone to strong odors.
For households willing to coach guests and family members on proper use, urine diversion can work reliably. In short-stay rentals or where many different users cycle through, consistent urine separation may be more challenging and affect overall performance.
Solid waste and toilet paper drop into the Simplett’s internal container underneath the seat. To support drying and composting, operators add a carbon-rich bulking material such as peat, sawdust, wood shavings, or a blend formulated for composting toilets. After bowel movements, a scoop or handful of this material is generally sprinkled into the container.
The Simplett does not fully compost waste to a finished, garden-ready state inside the toilet body. Instead, it acts as a first-stage collection and partial decomposition chamber. Final composting and pathogen reduction happen outside the toilet in a dedicated composting system, which must be built and managed according to local rules and best practices.
Ventilation is central to the Simplett’s ability to keep odors low. The toilet body connects to a vertical vent pipe that typically runs straight up through the roof or out and up an exterior wall. Natural stack effect and small leaks of conditioned indoor air into the toilet help draw air through the solids chamber and out the vent. In some installations, owners add a small, low-wattage fan to increase airflow, though the base Simplett system is designed to operate passively.
When properly vented and maintained, many users report that the Simplett produces less noticeable bathroom odor than some conventional flush toilets used with undersized or stressed septic systems. However, poor vent routing, very short vent runs, or lack of make-up air can reduce performance and lead to intermittent smells, especially in hot, still weather or when the house is tightly sealed.
Compared to a conventional flush toilet and septic system, installing a Simplett is relatively straightforward. However, it does require thoughtful planning around vent routing, urine drainage or collection, and local code compliance. These factors often determine whether a composting toilet is a good choice for your property.
The Simplett is a floor-mounted fixture similar in footprint to a compact toilet, but the body extends higher in the rear to accommodate the solids container and vent connection. It can fit in small bathrooms, bunkies, or cabin corners where plumbing a drain stack and water line would be more complex.
In tiny cabins or outhouse-style buildings, reserving a small, well-ventilated space specifically for the Simplett can simplify installation and make ongoing maintenance easier.
The vent pipe is often the most important technical detail of a Simplett installation. Best practice is to route a dedicated, mostly vertical pipe from the toilet through the roof or along an exterior wall, with as few bends as possible.
In some cottages and cabins, running a straight vent through the roof structure is easy. In others, rafters, beams, or loft spaces may require offsetting the pipe. Each additional fitting can add resistance to airflow, so planning the vent route early in your design is helpful.
Because the Simplett diverts urine out of the solids container, you must choose how to handle this liquid stream. Options vary by jurisdiction and site conditions, so it is important to check local regulations before choosing a strategy.
Whichever method you choose, the urine path should be protected from freezing where winter temperatures drop below freezing, and from backflow or cross-contamination. In very cold climates, keeping the urine line as short as possible and routing it through conditioned or insulated space can reduce freeze risk.
Composting toilets occupy a complex regulatory space that varies widely between states, provinces, and municipalities. Some regions explicitly allow certain certified models as full or partial replacements for flush toilets, while others require at least one conventional fixture tied to an approved septic or sewer system.
Even if a Simplett is technically easy to install, it is only a practical solution if you can operate and maintain it legally and responsibly over the long term. For many cottage and cabin owners, the Simplett ends up being one component in a broader on-site wastewater strategy rather than a standalone replacement for all plumbing.
From a user’s perspective, a well-installed Simplett can look and feel similar to a compact, modern toilet. However, the habits around flushing, adding cover material, and emptying containers differ from a conventional system. Understanding these day-to-day realities helps determine whether the Simplett matches your household’s preferences.
The Simplett is designed with a seat height and footprint that many adults find familiar. There is no visible water in the bowl, and when bulking material is used regularly, most users do not see raw solids. That said, there are a few operational differences.
In everyday use, a properly vented Simplett typically has a faint earthy smell around the bowl if the lid is opened briefly, but the bathroom air can remain neutral or slightly fresher than in rooms with poorly vented flush toilets. Users who are sensitive to any odor may notice differences from conventional fixtures, while others adapt quickly and are comfortable with the system.
Owning a Simplett means you will store and handle bulking material regularly. For many cottage and cabin owners, this becomes a normal part of seasonal routines and is similar to stocking firewood or pellets.
From a budget standpoint, the cost of bulking material is an ongoing operating expense, offset for many owners by lower water and septic system costs. The actual cost will depend on local availability of sawdust or shavings, whether you use bagged products, and how heavily the toilet is used.
Odor performance depends heavily on how consistently the toilet is used according to instructions and how effective the vent and urine separation are. Under the light to moderate use scenarios the Simplett is designed for, and with good airflow, many owners report manageable or minimal odor. Problems tend to arise when the system is overloaded or when key maintenance steps are skipped.
Routine inspections of the vent pipe, urine line, and solids container level are generally enough to catch most emerging issues before they become major problems. Households that are attentive to maintenance usually see the best day-to-day performance.
Unlike flush toilets, which hide most waste handling in underground tanks or distant treatment plants, the Simplett brings that responsibility closer to the owner. Understanding the maintenance workload and the steps involved in handling solids and liquids is key to deciding if this system is the right fit.
The solids container inside the Simplett fills gradually with a layered mix of human waste, toilet paper, and bulking material. Depending on use level, it may need to be emptied anywhere from every few weeks during busy seasons to only a few times per year for light, seasonal use. The exact interval will depend on occupancy, frequency, and how much cover material you add.
Owners who are comfortable dealing with garden compost or animal bedding often adapt quickly to this process. For others, this hands-on contact with human waste, even in partially decomposed form, can be a barrier to adopting a composting toilet system. Clarifying your comfort level and who in the household will handle these tasks is an important part of the decision.
If you use a portable container for urine, it will need more frequent emptying than the solids bin, because the volume of daily urine is typically much higher than the volume of solids. In busy periods, a small container may need service daily or every few days. Larger containers or direct-drain systems reduce the frequency but can add complexity in freezing climates.
With regular care, urine routing can remain a mostly background operation. Neglecting inspection and cleaning can lead to odors, crystallized blockages, or slow drainage that undermines the performance of the entire system.
The Simplett’s internal container is a first-stage collection and decomposition chamber. Long-term composting of the material typically takes place in an outdoor bin or series of bins that provide enough volume, aeration, and retention time for pathogens to break down and the material to stabilize.
Cottage and cabin owners who already manage compost for gardens or landscaping may find it straightforward to add a dedicated human-waste compost stream following local rules. Others may prefer to work with a professional hauler or disposal service if available, particularly in areas with strict regulatory requirements.
The Biolan Simplett is best viewed as a low- to moderate-use system, especially in cooler climates where composting progresses more slowly. Its strengths and limitations become most evident when you match the system’s capacity to your actual usage patterns throughout the year.
Manufacturer guidelines typically describe an approximate maximum number of users or visits per day. In practice, capacity is influenced by how much bulking material is added, how well urine diversion works, and the temperature and humidity around the toilet.
Planning for busy weekends, holidays, or rental periods is important. If the solids container is nearly full at the start of a high-occupancy week, odors and overflow risk increase. Regular checks before peak use can prevent this kind of overload.
Seasonal or intermittent use is where the Simplett often fits most naturally. In these scenarios, waste builds up gradually, containers can be emptied and composted between stays, and cold-weather challenges are minimized if the cabin is closed during freezing months.
Many full-time households pair a Simplett or similar dry toilet in one bathroom with a conventional flush toilet elsewhere in the home. This hybrid approach can reduce water and septic loading while providing a familiar backup for guests or for periods when composting toilet maintenance is less convenient.
In cold climates, the Simplett faces two main challenges: urine line freezing and slowed composting rates. The solids container itself can serve as a holding chamber during cold periods, but liquids and vent performance need particular attention.
Where cabins are not kept above freezing, most composting activity inside the toilet will pause during winter. This is usually not a problem structurally, but it does mean that most decomposition will occur later in the outdoor compost system after transfer in warmer seasons.
A key reason many cottage and off-grid owners consider the Biolan Simplett is its potential to reduce water use and environmental impact compared with conventional flush toilets and septic systems. The environmental footprint of a Simplett system depends on how it is installed, how the compost is managed, and what it replaces on the property.
The Simplett is fully waterless at the point of use, which can significantly reduce water demand in buildings that would otherwise rely on limited well capacity, rainwater catchment, or hauled water. In off-grid contexts, this can free up water for other uses like washing, cleaning, and irrigation.
These savings come with tradeoffs around bulking material production and handling, but for many cabins and seasonal homes, the overall water-use reduction is substantial.
By keeping solids and much of the urine on-site, the Simplett system makes it possible to return nutrients from human waste to soils rather than exporting them to centralized treatment plants. When managed safely, this can support healthier soil ecosystems and reduce the need for synthetic fertilizers.
In practice, many owners are conservative, applying finished compost only to ornamental plantings and forested areas, and routing urine to approved dispersal systems. Even with these conservative uses, the Simplett can support a more circular approach to nutrient use at the property scale.
The Simplett housing is typically made from durable plastic or composite materials designed to withstand moist, corrosive environments. While manufacturing these materials has an embodied carbon footprint, they can last many years with minimal replacement parts, especially in protected indoor environments.
For owners prioritizing low-impact infrastructure, particularly on sensitive waterfront or forested sites, the Simplett can be part of a strategy that balances durability with modest material and energy demands.
Based on how the Simplett is designed and how similar systems perform in comparable settings, several strengths tend to stand out for cottage and off-grid owners evaluating this model. These advantages are most pronounced when the system is installed correctly, matched to appropriate usage levels, and maintained consistently.
Owners who value these strengths and are comfortable handling bulking material and waste typically report the most satisfaction with the Simplett and similar urine-diverting composting toilets.
No composting toilet is a perfect substitute for a flush system in every setting. The Simplett has practical limits that become especially important in higher-use, colder, or more guest-heavy environments. A realistic view of these constraints can help you decide whether this model suits your property.
For some households, these limitations are acceptable trade-offs for water savings and independence from large septic infrastructure. For others, the day-to-day involvement and regulatory uncertainty may make a conventional system or a hybrid approach more appealing.
The Simplett’s design and performance characteristics point toward a set of scenarios where it tends to be a strong fit, and others where it is more of a niche or secondary solution. Mapping these scenarios to your own cottage, cabin, or off-grid home can clarify whether to move forward or to consider alternative options.
The Simplett often performs well in the following contexts, assuming proper installation and maintenance:
In these situations, the Simplett’s modest capacity, low water use, and straightforward mechanics align with owner expectations and available maintenance time.
There are also scenarios where a Simplett may not be the most suitable choice, or where additional planning is needed to avoid disappointment or performance issues.
In these cases, owners might still use a Simplett as an auxiliary or seasonal solution, but should consider whether other technologies, such as larger central composting tanks, advanced treatment units, or conventional septic systems, better match their needs and constraints.
If you are evaluating the Simplett, you are likely also considering other composting or waterless toilet options. While detailed brand-to-brand comparisons depend on specific models, it can help to understand where a compact urine-diverting unit like the Simplett sits on the spectrum of available technologies.
Some systems place a flush or low-flush toilet in the bathroom and route waste to a large composting chamber or drum located in a basement or under the floor. These central systems often have higher capacity and can serve as primary toilets for full-time homes, but they require more complex construction and usually higher upfront cost.
Owners deciding between these categories balance upfront investment and construction complexity against long-term convenience and capacity.
Incinerating toilets use electricity, gas, or other fuels to burn waste to a small amount of sterile ash. They require minimal ongoing handling of solids, but they trade water savings for energy use and typically need more robust venting and safety systems.
For owners with strong preferences against handling any solid waste, incinerating toilets may be worth considering, but they come with their own infrastructure and cost considerations.
In some rural areas, traditional outhouses or vault toilets remain common. These can be low-cost but raise concerns about groundwater contamination, odors, and ease of long-term management. A contained, vented system like the Simplett can offer a more controlled and, in many cases, environmentally responsible alternative, especially near sensitive water bodies or shallow soils.
For cabins transitioning from basic outhouses to more contained systems, the Simplett can be part of a gradual upgrade path toward improved sanitation and environmental protection.
If you are designing or renovating a bathroom with a Biolan Simplett in mind, a few layout and design choices can make ownership more convenient and comfortable. Thoughtful planning can also help integrate future upgrades or additions to your sanitation system over time.
Positioning the Simplett against a wall where a vent can easily rise straight up can simplify installation and improve performance. Ensuring clear access to the front or top of the unit for container removal avoids awkward maintenance later.
Locating the bathroom near an exterior wall can also simplify routing of the urine line to an outdoor container or drainage system, particularly if cross-floor plumbing is limited.
For cottages and cabins that host guests or short-term renters, repeated explanations of how to use a composting toilet can become tiresome. Simple, clear signage and easy-to-understand instructions can reduce confusion and misuse, improving performance and reducing owner workload.
Owner manuals, laminated quick-start guides, and occasional walkthroughs for new users can keep the system operating smoothly over time.
Choosing a waterless composting toilet is both a technical and lifestyle decision. The Biolan Simplett can provide reliable, low-water sanitation for many cottages, cabins, and off-grid homes, especially under light to moderate use with engaged owners. At the same time, it demands regular participation in waste handling, careful attention to venting and urine management, and adherence to local regulations around composting and disposal.
Evaluating your climate, guest patterns, water sources, and local rules alongside the Simplett’s operating characteristics will give you the clearest picture of fit. With realistic expectations and consistent care, many owners find that a system like the Biolan Simplett supports comfortable, low-impact living at the cottage or cabin.
When installed with a properly sized vertical vent and used as directed—with effective urine diversion and regular bulking material—the Biolan Simplett is designed to keep odors low. Most smell is drawn up the vent rather than into the bathroom. However, if the container becomes too wet or full, if the vent is blocked, or if urine diversion is inconsistent, odors can increase until those issues are addressed.
Emptying frequency depends on how many people use the toilet and how often. In light, seasonal use at a cottage, the solids container may only need to be emptied a few times per season. Under heavier, continuous use, emptying could be required every few weeks. Checking the fill level regularly and emptying before the container is completely full helps keep odor and handling manageable.
Yes, the Biolan Simplett can be used in winter, but cold temperatures slow or pause composting inside the toilet, and you must protect urine lines and vents from freezing and blockage. In unheated cabins, the toilet mainly functions as a holding container until you can transfer material to an outdoor compost system in warmer weather. Extra planning for insulation, line routing, and periodic checks is important in cold climates.
In some small, full-time homes, a Simplett can serve as the primary toilet if local regulations allow and if the household is prepared for frequent maintenance and careful composting. However, its capacity is better suited to low- and moderate-use scenarios. Many full-time households prefer a hybrid approach, pairing a composting toilet like the Simplett in one bathroom with at least one conventional flush toilet tied to a septic or sewer system.
Solid waste and toilet paper fall into the Simplett’s internal container along with bulking material, where they begin to break down and dry. When the container is partially full, you remove it and transfer the contents to a separate outdoor compost bin or managed waste container. Over time, in a properly managed compost system, the material stabilizes into a soil-like product. How and where you can use or dispose of that finished compost depends on local health and environmental regulations.
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