Best Composting Toilet For A Tiny House

Best Composting Toilet For A Tiny House

Living in tiny homes puts a lot of things in perspective, especially maximization of space, which makes finding a suitable composting toilet vital. 

If you don’t want to be encumbered with searching for water to flush the toilet when you’re supposed to be enjoying the great outdoors, then this guide might help you find the best composting toilet for a tiny house that will suit your needs.

We know how strenuous decision-making is, which is why we took matters into our own hands. We reviewed 5 of the top composting toilets available to help you come to an informed decision!

1. Sun-Mar Compact Self-Contained Composting Toilet, Model# Compact

The Sun-Mar compact composting toilet is the solution to waste treatment as it is 100% non-polluting. It can be easily installed anywhere without the hassle of plumbing connections, and with its size dimensions of 28.5 x 21.5 x 33 inches, the toilet is so compact in size that it takes up very little room. 

Quite a number of companies use the term “composting”  to describe their products when in reality they do not “fully compost” waste. This is a toilet that is capable of fully composting waste and is certified by NSF International.

The 90-pound toilet is built with a venting kit with a vent size of 2 inches. It is a self-contained toilet fitted with one drain and an emergency drain, and there is a thermostatically controlled heating element that aids the evaporation of excess urine. This heating element also provides the apt temperature that supports composting and ensures that any liquid output is safe.

Operating this toilet is easy, the two things you have to routinely do are add bulking material (approximately a cupful per person per day), and secondly, you will have to rotate the drum when it is approximately half full. The drum rotation is a periodic task that will ensure that when the time comes to empty the compost, you won’t have to deal with any fresh waste as everything would be well mixed.


  • Manufacturer: Sun-Mar
  • Part Number: CSEM-01400WB
  • Item Weight: 90 pounds
  • Item model number: COMPACT (white)
  • Color: White
  • Shape: Oblong 
  • Product Dimensions: 28.5 x 21.5 x 33 inches 


  • No need for external plumbing 
  • Higher than regular toilet 
  • Easy to install
  • No odor 
  • Comfortable 


  • Fiberglass cracks quickly
  • Drums are too small
  • The fan is loud
  • The drain for urine isn’t separate from compost

2. Separett Villa 9215 AC/DC

The Villa 9215 AC/DC released in 2018 replaces the previous Villa models. It is the most advanced, straightforward, low energy composting toilet that serves both on-grid or off-grid living because it functions with either electricity or solar power. It is waterless and urine-diverting, which means that the urine is separated from the solids under the seat by a cleverly designed urine-diverting bowl.

It has a single-speed fan that expels any ambient odor and excess moisture or condensation from the toilet and the bathroom quietly and effectively. The venting duct can be installed straight through the exterior wall eliminating underfloor plumbing. It runs further than 20 feet and has 3 height choices for vent direction. This toilet is so fancy that it comes with a weight-activated door, which means that the toilet slides open when weight is placed on the seat.

It leans towards the light side at 48.1 pounds, and its size dimensions of 38.25 x 25.25 x 25 inches make it compact enough to blend into your tiny house. It comes with 10 compostable bags, 1 waste container, a child seat accessory, a 5-year guarantee against manufacturing defects, and a 3-year fan guarantee. 

The toilet bowl catches the urine in a drain which is plumbed to a greywater system or holding tank, while the solid waste is transferred to the holding area in the compostable liner bag. 

The compostable liner bag takes over two months to fill and can be disposed of by sealing the bag and removing it from the holding area before transferring it to your waste-disposal area. This method alleviates the issues of attempting to fully compost waste while still in the toilet. The toilets are Intertec ETL certified.


  • Package Dimensions: 38.25 x 25.25 x 25 inches
  • Item Weight: 48.1 pounds
  • Manufacturer: Separett
  • Color: White
  • Shape: Oblong
  • Fan and Vent Size: 75 mm
  • Urine Outlet: 32 mm


  • Easy to clean and install
  • No under-floor plumbing 
  • Normal toilet height 
  • Exhaust fan 
  • Comfortable 
  • No odor
  • 5-year guarantee
  • Electricity, Battery, and Solar powered 


  • Need to connect an outside hose to drain urine

3. Sun-Mar Excel Non-Electric Self-Contained Composting Toilet, Model# Excel-NE

The Sun-Mar Excel non-electric self-contained composting toilet is the most amazing composting toilet that converts human waste into safe “humanure”. The NE model is designed for medium to high capacity use, ideal for 2-3 people in a residential setting or 5-7 people at a cabin for a weekend, and is NSF/ANSI certified. It has a bio-drum fitted with a recessed handle that allows the rotation of the compost in the unit. 

The handle is used to rotate the drum every two days to mix and aerate the compost. Once a month, you will need to roll the drum anti-clockwise to drop some compost into the finishing drawer where it remains for at least another month to completely break down. This means that you never have to handle any unbroken down waste. It also has a 5-year guarantee on the fiberglass tank and 3-year parts replacement on all other parts.

The toilet has no fan or heater but regulates temperature through one drain, an emergency vent kit, and the vent stack which is 4 inches in size. The toilet utilizes a diffusor at the top of the unit which draws away odor from the toilet just as a chimney draws smoke from a fire. 

The toilet is 33 x 22.5 x 32 in dimension making it the perfect description of compact-sized. This model does not run on electricity but is solar-powered. It is a waterless toilet suited to minimize ecological impacts.


  • Color: White
  • Installation Method: Floor Mounted
  • Shape: Oblong
  • Manufacturer: Sun-Mar
  • Part Number: EXCEL NE-WHITE
  • Item Weight: 81.1 pounds
  • Product Dimensions: 33 x 22.5 x 33 inches
  • Item model number: EXCEL NE (White)


  • Solar-powered
  • Easy to install  
  • Bio-drum for processing compost
  • Uses no water
  • 100% non-polluting
  • 5-year and 3-year guarantee 
  • No odor


  • The handle breaks easily 
  • Not recommended for everyday use
  • The fan consumes a lot of power
  • Drain tube not wide enough 

4. Sun-Mar GTG Composting Toilet || Portable Toilet, Compost Toilet for RV

The Sun-Mar GTG Composting Toilet is the ideal portable toilet because its first feature is that it separates solid and liquid waste materials, same as other Sun-Mar toilets. The GTG is a further extension of Sun-Mar’s innovative designs as it sets up in a matter of minutes. 

It is a breeze to install, all you have to do is mount it on the wall! It’s modern (European) styling and has its size dimensions of 24 x 15.75 x 19.8 inches making it an ultra-compact size.

It has an easy to remove seat/separator and the elongated seat easily connects and disconnects, giving you access to the composting material underneath the seat. Because of its dual-chamber design, the GTG efficiently separates liquid from solid waste into respective chambers. The liquid waste can simply be poured out, and the solid content can be easily removed by using a bag/liner for composting.

This composting toilet features a built-in fan/vent and transformer to decrease odor and catalyze the composting process by increasing aerobic conditions. It also doesn’t weigh too much at 29.5 pounds, and cleaning it is pretty straightforward – not messy at all. It runs on electricity but power consumption is low. It also comes with a spray bottle and wood-shavings to aid composting.


  • Manufacturer: Sun-Mar
  • Part Number: GTG Toilet
  • Item Weight: 29.5 pounds
  • Product Dimensions: 24 x 15.75 x 19.8 inches
  • Item model number: GTG Toilet
  • Color: White
  • Shape: Oblong
  • Installation Method: Wall Mounted
  • ASIN: B07Q626GHG


  • Portable 
  • Easy to install 
  • Great size
  • Compact
  • In-built fan
  • Low power consumption 


  • No return policy 
  • Fans don’t stop running 
  • Poor liquid funnel design 

5. Nature’s Head Composting Toilet with Spider Handle by Nature’s Head

Nature’s Head Composting Toilet with Spider handle is an eco-friendly dry toilet made of stainless steel hardware, designed to withstand the harshest of conditions. 

It is urine-diverting as it separates the solid from the liquid fecal matter, thereby eliminating sewage smell. It has a full-size elongated seat for comfort and the entire system disassembles in seconds for emptying. 

It comes with a composting handle that resembles a spider’s leg, which does not extend out as much as the standard handle making it easier to install in tight spaces. This handle can be mounted on either side of the toilet. The toilet’s size dimensions of 21.5 x 18 x 17.75 inches denote that it is ideal for tight spaces. 

It also has a vent hose and fan which may be mounted on either side of the toilet. The unit comes with everything for your installation except the external vent. Molded into the toilet for safety is a pouch for supporting the liquid tank to avoid spillage. The toilet weighs 28 lbs and so can be termed lightweight.

This liquid tank is semi-transparent to enable you to monitor the urine level, and you have to manually open a latch to direct your solid waste into the correct container. Liquid waste automatically drains into the correct container when the latch is closed. The toilet comes with a mixture bottle for spraying the toilet after use.


  • Manufacturer: Nature’s Head
  • Part Number: 3336600
  • Material: Stainless Steel 
  • Color: White
  • Gallon size: 2.2 liters 
  • Dimensions: 21.5 x 18 x 17.75 inches
  • Item Weight: 28 lbs.


  • No odor 
  • Extra Liquid overflow collector to avoid spillage 
  • Disassembles in seconds for emptying
  • Handle mountable on either side
  • Self-contained and portable
  • Easy to install 
  • 5-year warranty 


  • Opening up the solid tank trap before use
  • Not a large capacity toilet

Buyers Guide

What Are Composting Toilets?

Composting toilets recycle human waste by utilizing the natural processes of decomposition and evaporation. This means that waste entering the toilets – which is over 90% water, will be evaporated and carried back through the vent system into the atmosphere. The small amount of solid compost left is converted to eco-friendly “humanure” by natural decomposition.

This means a composting toilet must perform three important functions:

  • Compost the waste and toilet paper quickly and without odor
  • Ensure that the finished compost is safe and easy to handle
  • Evaporate the liquid

Why Get A Composting Toilet?

If you’re wondering why you should get a composting toilet when you could alternatively install indoor plumbing in your tiny house, you might want to consider these advantages:

  • Reduces water usage – you’re saving the environment 
  • Saves money – indoor plumbing costs a lot
  • Minimizes environmental impact – composting toilets are gifts to our ecosystem 

What To Consider When Buying A Composting Toilet

Here are a few details you could add to your list when considering a particular brand of composting toilet to buy:


The sizes of composting toilets vary, you have to know how much space is apportioned for your toilet and buy one that would fit into that measurement. 


Composting toilets don’t come cheap. You should have an outlined budget on how much you are willing to spend to get a comfortable and budget-friendly toilet that would serve its purpose of purchase.

Ease of Cleaning 

If you’re the type that can’t stand the sight of waste, you might want to go for a composting toilet that won’t give you a glimpse of waste when cleaning it. These toilets come with their spray bottle mixtures to assist with cleaning and extra bags for your waste.


It is no surprise that many brands have the absolute best machines based on functionality but when it comes to durability, the machine is strongly lacking. If you don’t want a toilet that will break down after 3 weeks of use, you might go for something sturdy and long-lasting. 

Your preferred composting toilet should be able to withstand harsh conditions and keep working for a long time before wearing out.

Maintenance and Repair Costs

Of course, nothing lasts forever, accidents could happen and parts could fail. Hence, you need to be sure of how expensive replacing parts of your toilet would be. This will go a long way to ensuring that you don’t dump your toilet because you can’t afford its replacement parts. You should also consider the cost of also maintaining the toilet, like purchasing the bulking materials and the bags when they run out.


Composting toilets are the best for tiny houses, as they are waterless/dry toilets that not only save water but also provide safe waste to act as manure for fertilization processes. We have armed you with enough background information on our top 5 best composting toilets. 

Whatever option you choose, remember that it has to be tailored to your every need. Save the planet, go green!

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