Best Composting Toilets: Reviews & Buying Guide

Best Composting Toilets: Reviews & Buying Guide

  • Posted by Tatiana
  • On March 17, 2021
  • 0 Comment

Eco-friendly living is all the rage now, and people are constantly looking for ways of making their homes more sustainable.

One of the ways of doing it is installing the composting toilet. This toilet, also known as waterless, composts solid waste using a medium, so you can dispose of it in the soil or even use it as a fertilizer!

If this caught your attention, scroll right below, and you will find the best composting toilets and a comprehensive buying guide that will help you choose a unit for your needs.

Quick Picks

Best Overall

2nd Best — Composting Toilet With Urine Diverter

3rd Best — Composting Toilet for Long-Term Use

Nature's Head Dry Composting Toilet with Standard Crank HandleSeparett Villa 9215Nature's Head Self Contained Composting Toilet with Spider Handle Design
21’’ high bowl; needs emptying every 2-3 weeks the fan can vent the air up to 20 ft; can operate from grid or batteries the composting section holds 60-80 uses; 2.2-gallon urine bottle

How Does a Composting Toilet Work?

A toilet that doesn’t use water? You must be joking!

No, it’s a fact:

The decomposition process doesn’t require water, only a carbon-rich medium — such as peat, coco coir, tree bark, or leaves — and some oxygen, so the aerobic bacteria can do their job. 

The key to a quick and proper decomposition process is maintaining the balance between carbon and nitrogen, ensuring optimal aeration, humidity, and temperature settings. And your toilet is pretty much equipped with all the necessities for it:

  • Fan. Modern composting toilets have a built-in fan that, along with removing gasses and residual odors, supplements the bacteria with oxygen and reduces excess moisture. Solid human waste contains water, which is enough for the bacteria to grow, but too much moisture can drown it, so the fan ensures air circulation inside the compost bin and prevents that from happening.
  • Urine diverter or urine bottle. Mixing solid and liquid waste stops the decomposition process because urine contains too much nitrogen and can disrupt the microbiome. That’s why modern toilets either have a separate container for the liquid waste or can be connected to the drainpipe to remove the urine.
  • Mixers. To facilitate the decomposition process, waste should be thoroughly mixed with a composting agent, To do this without getting inside a compost bin, modern toilets have a crank or a spider handle, which incorporates the medium particles into the waste. Also, the handle serves as an indicator for cleaning: when you feel like it’s become hard to move, then it’s probably time to empty the toilet.

And there you have it!

The final product of decomposition is a humus-like substance that smells like damp soil. Most states require you to dispose of it with the licensed septic hauler in your area. But in states, where the soil amendment is permitted, you can use this humus as a fertilizer for non-edible plants in your garden (1).

Our 3 Best Composting Toilets

Best Overall — Editor’s Choice

Nature’s Head Dry Composting Toilet with Standard Crank Handle

Highlights:
  • crank handle agitator for fast composting;
  • includes 5-feet long vent hose;
  • works for 2-3 weeks between emptying  (when used by 2 adults);
  • completely odor-less;
  • works with peat or coco coir fibers as a medium.
Nature's Head Dry Composting Toilet with Standard Crank Handle

Let’s start our review with the absolute best composting toilet on the market by Nature’s Head. This model has comfort height, an odor-free design, and can be a great pick for those who live in places where connection to sewers is limited.

So, the toilet has two separate containers: a 2.2-gallon urine bottle, and a solid waste container. Note that everyone needs to pee in the sitting position to ensure that the urine goes right into the bottle, and not in the solid container. The urine bottle needs to be emptied every other day.

The solid waste container uses peat or coco coir as a composting medium and needs to be emptied every 2-3 weeks if used by two adults. After you do your job, crank the handle to let some air in, and that’s it. The toilet also requires a 12V socket for a fan, removing the gasses and residual odors from the container.

The toilet bowl measures 21’’ high, which is beyond ADA regulations but can be comfortable for people with bad knees or taller than 6 feet. Also, the Nature’s Head is made of hard plastic, making it easy to clean and transport.

Pros:

  • Needs to be emptied less frequently than cassette or self-containing toilets
  • Can work for tall individuals thanks to the 21’’ bowl height
  • A crank handle facilitates the composting process by adding some air inside the container

Cons:

  • The pellets of coco coir or peat can take up space in the van or cabin
  • Depends on electricity for more efficient work

Best Composting Toilet With Urine Diverter

Separett Villa 9215

Highlights:
  • diverts urine into the gray water system for a less wasteful experience;
  • made of high-impact polypropylene;
  • powerful single-speed fan vents the gasses up to 20 ft;
  • AC (power grid) or DC (battery) operation;
  • comfortable oblong bowl.
Separett Villa 9215

The next pick for our composting toilet review is the Villa 9215 by Separett. Its main advantage is the urine diverter, which allows you to connect the toilet to the gray water tank or sewers, which makes it low-maintenance. However, this isn’t the only good thing about it.

When used by a standard household, the solid container should be emptied every 2 months, which makes it extra efficient. Plus, the toilet comes with three interchangeable composting bins, so you’re stocked for 6 months of use right at the start.

Another great thing about the Villa is that it can use both AC and DC power sources for the electric fan that drives the odors away. For grid operation, you will need a 120V US socket, and the toilet itself needs only about 0.3-0.45kW per 24 hours, which is a pretty low consumption.

Finally, the Villa is a good pick for those who suffer from mobility limitations: it measures 26.4’’L x 17.9’’W x 21.2’’H, which is higher than ADA recommendations but might work for tall users or those who need some extra help with their bathroom visits.

Pros:

  • A composting bin needs cleaning every 2 months, which is longer than similar models
  • Urine diverting system reduces maintenance of the toilet
  • Is higher than standard models and can suit tall users

Cons:

  • Made of plastic, which means it may start to retain odors sooner or later
  • Might not fit short users

Best Composting Toilet for Long-Term Use

Nature’s Head Composting Toilet with Spider Handle Design

Highlights:
  • the solid tank holds 60-80 uses — that’s up to 1.5 months between cleanings;
  • spider handle makes the toilet more compact;
  • 20’’ high bowl;
  • weighs only 28 pounds when empty;
  • completely odor-free.
Nature's Head Self Contained Composting Toilet with Spider Handle Design

And the last of the commodes we picked for our composting toilet review is another model by Nature’s Head. This time it’s the toilet with the spider handle, which takes 2’’ less space compared to the crank handle. But the most awesome feature of this toilet is its larger tank that can hold up to 80 uses, which is great if you travel by RV or live somewhere without a connection to sewers.

So, the toilet has separate containers for liquids and solids: a 2.2-gallon urine bottle and the composting tank. Generally, the urine bottle needs emptying every 2 to 5 days, and the solid tank will last you up to 1.5 months depending on the use.

After you do your job, turn the spider handle to mix the waste with a composting medium and let some air in to start the composting process. When the handle feels hard to turn, it’s time to empty the bin. 

The toilet has a built-in fan that removes residual odors and gasses and makes the composting process faster. The fan requires a 12V plug or a battery to work, so be sure to take that into consideration.

Pros:

  • Needs emptying way less often than other composting toilets
  • Comfortable bowl height for everyone
  • Easy to clean and requires low maintenance

Cons:

  • Can get quite heavy to move when full
  • The fan CPU can glitch sometimes

What Makes the Best Composting Toilet?

Dimensions

Most composting toilets don’t differ from your regular commode in dimensions. The only major difference is the agitator handle that can extend to the side and requires some extra space to accommodate it.

Also, some dry composting toilets, such as those made by Nature’s Head, have an extra high bowl (20-21’’). This falls beyond the Americans with Disabilities Act (ADA) but can still be comfortable for those who have bad knees or are taller than 6 feet.

Tanks Capacity

The size of the toilet’s compost bin and the urine bottle — in case if your commode doesn’t have a urine-diverting system — will define how often you will have to empty it. 

Generally, the urine bottle needs to be emptied every 2 to 5 days depending on the use. The solid waste bin will last you from 1.5 to 6 months which also depends on the following factors:

  • Frequency of use. An average adult needs to use a toilet 1-2 times per day to do a Number Two. The regular composting toilet can hold up to 60-80 uses for a solid tank which means that it may last you 1.5-2 months. If you live with someone, the time will proportionally decrease for 3-6 weeks for two adults, 2-4 weeks for three adults, etc.
  • Location. If you purchase a composting toilet for a remote cabin that is inhabited for 2-3 months per year, your toilet will last significantly longer. Moreover, you can even leave the waste to fully compost when the cabin is not in use.

Power Source

The built-in fan in the composting toilet needs electricity to run, either a battery or a socket. Battery-operated toilets are more suitable for off-grid locations, RVs, and other places where connection to a socket is limited. On the other hand, plug-in toilets are more reliable and long-lasting. Don’t worry, it doesn’t use that much energy, and the fan is shutting down automatically.

Ease of Emptying

Finally, a composting toilet can get quite heavy as the solid waste bin fills up. So it should have a convenient design that allows to empty it single-handedly. Modern composting toilets usually have a detachable solid waste tank that can be emptied and hauled away, or come with several interchangeable bins, which allows you to let the waste decompose entirely for several months.

Tips for Maintaining a Composting Toilet

A composting toilet is pretty different from your regular commode, and it needs to be maintained differently as well. Here are some recommendations on how to care for the composting toilet so that it will serve you for years:

  • Sit on the toilet while you do your job. Yes, even if you’re a male. Peeing in the sitting position reduces the chances of urine entering into a solid waste chamber, resulting in an unpleasant sewage odor. 
  • Turn the agitator every time you use the toilet. This will help break the waste and composting agent mixture into smaller chunks and aerates it, promoting bacteria growth and facilitating decomposition.
  • Don’t put toilet paper or other hygiene products into the bin. Toilet paper will significantly slow down the composting process and may make you empty the toilet more frequently. Hygiene products that contain plastic and synthetic materials don’t compost at all, so you need to utilize them separately.
  • Monitor liquid and solid bins. Make sure you empty the urine bottle regularly to prevent overflowing and bad odors. Also, monitor the compost bin’s state: if the agitator handle feels challenging to move, it’s time to empty the bin.
  • Do not add liquid into the solids bin. The composting agent should be moist but maintain a crumbly structure. Usually, water contents in the human waste are sufficient to keep it moist, but if you think that the mixture feels too dry, you may spray some water on it.
  • Do not use regular soil as a composting agent. Aside from composting agents, regular soil may contain pathogen microorganisms as well as insects or worms. These definitely aren’t things you want inside your toilet.
  • Maintain proper nitrogen-carbon ratio with additives. Good compost needs a nitrogen-carbon ratio of about 1:30 (2). Human waste contains a high amount of nitrogen compounds, so you need to add carbon-rich agents, such as sawdust, wood chips, or bark to balance them and help compost bacteria to thrive.

FAQ

The main advantage of a composting toilet is that it doesn’t use water for flushing (or uses a tiny amount to keep the composting agent moist), so you can reduce your water use per household. Also, composting toilets can be installed in places where connection to plumbing or electricity is problematic, such as RVs or cabins.

Although certain toilets do use water for flushing, most of them don’t require liquid to function, and the composting process is governed by heat and aeration through the fan and vents.

This mainly depends on how well you use it, but urine bottles should be emptied every 2-5 days, and the solid waste tank will last you up to 2 months or even longer if you buy a toilet for a remote location.

Some states prohibit burying the humus from a composting toilet, while others don’t. To make sure that you won’t break the law, it’s better to contact your sewage haul organization or local plumber.

After each use, you can wipe the toilet with a cloth soaked in a mixture of water and vinegar. This will ward off odors and remove stains. Also, after you remove the compost from the bin, thoroughly rinse the toilet with water and soap, and let the bin dry out before you place a composting agent.

Owner - Mary O. Frazier

Founder

Mary O. Frazier

Mary O. Frazier — lead author of our website, connoisseur of interior design and plumbing. I will tell you the most interesting and important facts about household items. She reads a lot, plays chess and collects useful information for you. You can read more about her here.

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