Sun Mar Composting Toilets: A Detailed Review

Sun Mar Composting Toilets: A Detailed Review

Aug 14, 2023

Sun Mar, renowned for its innovative composting technology, has been pioneering green solutions since 1979. Their range of composting toilets, distinguished by their eco-friendly design and user-friendly operation, has carved out a unique niche in the sustainable living market.

This article will delve into a detailed review of Sun Mar's composting toilets, examining their features, benefits, and how they compare to other products on the market. Whether seeking to reduce your environmental footprint or embrace a more sustainable lifestyle, Sun Mar's products offer a compelling proposition.

What is Sun-Mar?

Sun-Mar is a leading manufacturer and global distributor of composting toilets and composting technology. The company is renowned for its innovation and commitment to sustainability, offering products designed to minimise environmental impact and promote eco-friendly living.

From compact composting toilets ideal for small spaces to larger systems designed for residential use, Sun-Mar provides solutions that are beneficial to the environment and user-friendly. Their products are characterised by their high-quality design, sound functionality, and ease of installation.

With a steadfast commitment to providing green solutions, Sun-Mar is a good toilet that supports sustainable living and waste management, but the reviews online are mixed.

We will get into that in a moment, but here is just one review that goes into the reality of managing a composting system like this that many first-time toilet buyer don't learn until it's too late.

In case the text is too small for you to read, here's some of the quotes of the review from an owner:

"I despise when we have to do a deep clean. We didn't empty it often enough or our "mix" wasn't quite right and the liquid diverter drain clogged."

"Ours can develop an odour, but it seems that is only when it isn't being emptied often enough or you have, like in our case, a clog."

"We have it in an enclosed shed so it isn't a small space space and it is not built very tight so there is air leaks 24/7."

"It can be messy to clean out, they do not hold a ton so guests may have to take the finishing tray out to dump."

"They recommend adding peat moss in that needs to be stored and creates a bit of dust when dumped in."

This is why it's important to read reviews online!

How Do Sun-Mar Composting Toilets Work?

This self-contained toilet functions on a simple yet effective principle of composting, replicating the natural decomposition process that occurs in nature. These toilets leverage three essential components for composting: organic waste, bacteria, and oxygen.

When organic waste is deposited into a Sun-Mar composting toilet, aerobic bacteria within the system break down the waste. This decomposition produces heat, which in turn accelerates the composting process. The heat also serves another purpose: it evaporates excess moisture, vented away through a dedicated exhaust system.

The distinguishing feature of Sun-Mar's composting toilets is their patented Bio-drum™. The Bio-drum™ provides an optimal environment for aerobic bacteria to work, and it's easy to rotate — turning the rotating drum speeds up decomposition and helps to distribute moisture and oxygen evenly.

Finally, the completion drawer at the bottom of the unit allows for removing finished compost, a nutrient-rich material that's safe and beneficial for gardening purposes. The entire process is clean, odor-free, and environmentally sustainable.

What makes Sun-Mar unique in the composting toilet Industry?

Sun-Mar holds a distinctive position in the composting toilet industry due to its technology, product range, and commitment to sustainability.

Unlike conventional composting toilets, Sun-Mar's units leverage a patented Bio-drum™ mechanism, providing an optimal environment for composting and enabling users to speed up the process easily.

The company's innovative approach extends to its comprehensive product range. Sun-Mar offers a diverse selection of composting toilets, catering to different needs and spaces, from compact units perfect for smaller homes or RVs to larger systems designed for full-sized residences.

Sun-Mar's commitment to sustainability is another aspect setting it apart. The company doesn't just produce composting toilets; it provides green solutions that promote sustainable living. Its products help users reduce their environmental footprint by transforming waste into a rich, safe compost ideal for gardening.

Moreover, Sun-Mar prioritises user experience, ensuring that their composting toilets are environmentally friendly and easy to install and operate. Their systems are advertised as odour-free with require minimal maintenance, however many online reviews state otherwise.

On Amazon, 23% of reviewers give the toilet a 1-star review.

Here are just some of the headline from those reviews...

Although they are committed to green living and eco-conscious toilets, it's still critical that they work well and it seems that at least some customers are far from delighted.

23% 1-Star reviews is not great.

By comparison, the Dry Flush toilet that we sell here on this website averages 9.9/10 across 1,324 independent reviews from owners on

Here is just some of those clients:

Sun-Mar Product Lines

Sun-Mar offers a variety of product lines to cater to customers' different needs and requirements.

Residential Composting Toilets

Sun-Mar's residential composting toilets are designed for full-time use in homes and cottages. They are fully self-contained units that can be installed in any part of the house without the need for a water connection. These toilets come in electric and non-electric models, providing options for those living off-grid or wanting to reduce their energy consumption.

As you can see from the images though, these toilets are nowhere near as streamlined as our Dry Flush toilets, and they still have many of the draw backs of composting toilets (listed below & shown in the reviews above).

Mobile Composting Toilets like the Sun Mar in RV's, vans and tight spaces... 

The mobile toilet range is ideal for RVs, boats, and trailers, providing a sustainable solution for those on the move. Compact and lightweight, these units try to ensure that you can enjoy the comforts of a regular toilet without worrying about harmful environmental impact, however they seem to fall short on several fronts based on the client reviews.

Clogs, urine handling, smell and more are in fact part of life when you choose a composting toilet.

Here's one good example of the reality of using this toilet for this purpose.

Garden Composters

Sun-Mar’s garden composters are designed for those seeking to enrich their garden soil naturally. These composters effectively transform kitchen scraps and garden waste into nutrient-rich compost.

They feature the same Bio-drum™ technology found in toilets' composting, ensuring efficient composting. With a variety of sizes available, Sun-Mar has a composter to fit any size garden.

That being said, you cannot put this compost onto any plants that are growing food!

Sun-Mar’s product lines ensure a green solution for everyone, regardless of their living situation or lifestyle. Whether you're a full-time resident looking for a sustainable toilet solution, a traveller needing a mobile option, or a gardener seeking to enrich your soil, Sun-Mar has a product designed with you in mind.

Just remember, READ THE REVIEWS online.

Installation Process Of Sun-Mar Composting Toilets 

The installation process of Sun-Mar composting toilets is straightforward and user-friendly, designed to be manageable by even the most inexperienced homeowners.

Here's a step-by-step guide to installing your Sun-Mar composting toilet.

Step 1: Choosing the Location

The beauty of Sun-Mar composting toilets is that they can be installed almost anywhere in the house. However, it's important to ensure that the chosen location has access to a power source (for electric models) and a way to vent the unit outdoors.

Step 2: Vent Installation

The vent is a critical component of the composting toilet, responsible for expelling excess moisture and ensuring an low-odour experience. The vent should be run from the unit, through the wall or roof, and extend at least two feet above the highest point of the roof.

Obviously this is far more complicated than our Laveo Dry Flush system that requires no vents or fans at all.

Step 3: Installing the Unit

Place the composting toilet at the chosen location, ensuring it is level. If necessary, the unit can be raised on a platform to make it a comfortable height.

Step 4: Connect the Vent

Attach the ventilation pipe to the composting toilet, ensuring a secure fit. The other end of the vent should be externally located as specified in Step 2.

Step 5: Power Connection

For electric models, the unit will need to be plugged into a standard outlet. Non-electric models won't require this step.

Step 6: Initial Set-Up

The initial set-up of the unit involves adding peat mix (or any other bulking agent recommended by Sun-Mar) and water to the Bio-drum™. This creates the perfect environment for the composting process to start.

As you can see, the installation process of Sun-Mar composting toilets is fairly simple but certainly not easy for everyone.

Always refer to the detailed instruction manual provided with your unit for specifics related to your model.

Maintenance of Sun-Mar Composting Toilets 

Maintenance of Sun-Mar composting toilets is designed to be minimal and user-friendly, but if you miss anything, things can get messy and smelly.

The company understands that ease of use plays a significant role in the user experience, so they have done their best to develop a system that require simple, straightforward care, but it still causes a lot of people issues if you read the online reviews on Amazon and other forums.

  1. Regular Use of the Bio-drum™: To ensure efficient composting, it's important to regularly turn the Bio-drum™. This can be done with the handle provided, making it an easy task even for those with limited physical strength. Regular turning helps to aerate the compost and speed up the decomposition process.
  2. Addition of Bulking Material: From time to time, additional bulking material such as peat mix or wood shavings should be added to the composting toilet. This helps to create the right environment for the composting process and aids in controlling moisture levels.
  3. Emptying the finishing drawer: Once the composting process is complete, the finished compost will be moved to the finishing drawer. This drawer should be emptied approximately every 2-4 months, depending on the number of users and frequency of use.
  4. Vent Maintenance: The venting system ensures that the unit remains odor-free. It's important to check this vent periodically to remain clear and free from obstructions.
  5. Cleaning: Like traditional toilets, Sun-Mar composting toilets require regular cleaning within central systems. However, users should avoid using harsh chemicals, which can disrupt composting. Instead, natural cleaning solutions are recommended.

Overall, while some maintenance is required, Sun-Mar works hard to ensure their composting toilets are easy to care for. The goal is to provide a sustainable toilet solution that is good for the environment and simple and convenient for the user.

Material Composition of Sun-Mar Composting Toilets 

Sun-Mar composting toilets are carefully constructed using durable and eco-friendly materials, ensuring quality and sustainability.

The exterior is typically made of high-strength, lightweight plastics like polyethylene, providing longevity and easy cleaning. These non-porous materials are resistant to bacterial growth, thus promoting hygiene.

The internal Bio-drum™, the heart of Sun-Mar's composting technology, is typically fashioned from stainless steel. This material is chosen for its rust-resistant properties and ability to withstand waste's corrosive properties over time. Moreover, stainless steel helps retain heat, an essential factor for efficient composting.

As for the finishing drawer and the handle for the Bio-drum™, they're often composed of sturdy and lightweight metals or high-strength plastic, delivering durability and ease of use. The vent stack, crucial for maintaining a low-odour environment, is generally designed from PVC piping, known for its longevity and resistance to environmental elements.

Pros and Cons of Sun-Mar Composting Toilets 

Like any product, Sun-Mar composting toilets have their advantages and disadvantages. Understanding these can help potential users make informed decision.


  1. Sustainability: One of the most significant benefits of Sun-Mar composting toilets is their environmental friendliness. These toilets transform waste into nutrient-rich compost, reducing water usage and eliminating the need for sewage systems. Just remember - not on your food plants!
  2. Relatively Easy Installation: As outlined above, the installation process for Sun-Mar composting toilets is relatively simple but it could require professional help.
  3. Low Maintenance: These composting toilets require minimal maintenance for a composting toilet, but all composting toilets are notoriously painful if they play up. If you do get this toilet, make sure that you regularly turn the Bio-drum™ and add the bulking material.
  4. Low-Odour IF you stay on top of the maintenance: Sun-Mar composting toilets are designed to be odour-free but many folks report that they are not. You can be the judge of that when you read the many reviews online.
  5. Quality Materials: Sun-Mar composting toilets are made from high-quality, durable materials, ensuring longevity and hygiene.


  1. Price: Sun-Mar composting toilets tend to be more expensive upfront than traditional toilets, which might be a deterrent for some individuals.
  2. Manual Handling of Compost: While the composting process is natural and sanitary, some people may not be comfortable handling the finished compost.
  3. Dependency on Electricity: Some models of Sun-Mar composting toilets rely on electricity for the composting process as well as the fans and vents that constantly need to be running to keep the smell out, which could be problematic in power outages or if you have limited power wherever you are.
  4. Occasional Maintenance required: Despite being low-maintenance, Sun-Mar composting toilets still require more maintenance than traditional ones, which could be a con for some people.

In conclusion, while there are a few cons to consider.

Pricing of Sun-Mar Composting Toilets 

When it comes to the pricing of Sun-Mar composting toilets, it varies according to the model and specific features offered. The compact, self-contained models suitable for single or occasional use are usually priced in the lower range. In Australia, they will cost around $3,500.

​On the higher end, Sun-Mar offers advanced, centralised composting toilet systems that can cater to larger families or small businesses.

It's important to note that while the initial investment may seem significant, the long-term savings in water bills and sewage maintenance can offset the upfront cost.

​For those on a tight budget, Sun-Mar products also offers non-electric models and mobile versions for RVs and boats, which come in at a more affordable price points.

As always, prices may vary depending on the retailer, location, and additional installation costs or accessories needed.

Obviously, we would encourage you to look at our Laveo Dry Flush toilet which is available on this website. We are the exclusive distributors for this rpoduct in Australia and New Zealand.