Composting Toilets: All You Ever Wanted To Know

by heather

Many people have a lot of misconceptions when they hear the words “composting toilets”. Immediately they think “outhouse” or imagine a hole in the ground. Yucky, smelly, and a little drafty.

Well, the composting toilets of 100 years ago (the outhouse) and the composting toilets of today are completely different creatures.

Today’s composting toilets are sleek, efficient, and entirely odor-free. So hang on. We’re going to go take an in-depth look at our stinkier side, and learn how composting toilets can allow us to become more eco-friendly and completely “waste free”.

The Facts On Our Waste

Courtesy of

According to the Environmental Protection Agency, septic tanks are a big cause of groundwater pollution. On average, a family of 4 puts 150 gallons of water into a septic tank each day.

You’ve probably never really thought about it, but where does all that water go, anyway?

Well, septic tanks are designed to have a “leach field” or “drain field” around them. Here’s how it works:

Most septic tanks are 1,000 gallons or larger. Wastewater flows in the tank on one end, and is drained into the surrounding area through the other.

At the bottom is the sludge layer. I’ll let your imagination tell you what’s down there.

At the top is the scum layer (no I did NOT make up these terms, that’s really what it’s called).

In the middle of those two yucky layers is the wastewater that gets drained out. That is, the excess water is drained into the dirt below, and the solid “waste” is left behind to dissolve in the tank.

Think that excess water is 100% pure? Hardly. It’s loaded down with pollutants like bacteria, phosphates, and nitrates, all of which harm local watersheds. Yuck.

According to the “Humanure Handbook“, up to 1,460 billion gallons of this water is leached out of septic tanks each year in America.

That’s an awful lot of dirty water that’s going into our streams and rivers. Yikes.

Now, the soil is a natural filter. Out in the country, there’s plenty of open space for the land to naturally filter all these contaminates out. The problem comes in densely packed urban areas, such as subdivisions. If 30 homes in a neighborhood all have a septic tank, the soil can’t handle all the leach water. So, pollution occurs.

Courtesy of

Benefits To Using A Composting Toilet

The cool, amazing thing about composting toilets is that they cut all of this mess out. There’s zero pollution, zero waste, and zero lost water.

Here’s the rundown:

Envirolet estimates that composting toilets reduce household water use by 60%

In fact, Sun-Mar composting toilets estimate that an average family of four flushes 70 gallons of water down the toilet every day, which is a whopping 25,000 gallons per year. They estimate that based on all the composting toilets they’ve sold in the past, their company alone is saving 6,103 gallons of water every minute.

They also keep you from “depending” on your septic tank or city wastewater treatment facility. Ever been in a natural disaster, when the city couldn’t process your water (and thus you couldn’t flush your toilet)? That dependence is completely eliminated with compost toilets.

You can also use the system to compost food scraps and lawn clippings. Try putting those things down your current toilet. Yeah right.

They’re truly environmentally friendly. Neat.

Now the only downside here is that if you live in an apartment, or you’re renting a home, installing a composting toilet isn’t going to be an option. But perhaps your landlord might be interested to hear just how much water these babies save per year. Those savings really add up, and these composting toilets pay for themselves in just a few years.

How Do Composting Toilets Work?

Composting toilets work by quickly dehydrating 90% of the liquid that’s in our waste, and then composting the remaining 10% solids that are left. We can then use those solids, called “humus”, as additive for lawns.

Think I’m kidding here? It’s no joke. You really can turn your poo into garden soil. Let’s continue onward for more detail…

Types of Composting Toilets

There are 2 broad “types” of composting toilets.

Batch systems, or self contained systems (like the picture up above, on right), are “all in one” units. The waste is composted in a tray at the bottom. See that pipe sticking up behind the toilet? That a ventilation pipe. A small wind turbine that’s at the top of that pipe, on your roof, is what keeps the unit completely odor-free.

These systems are designed for lighter use (two person households, or occasionally used vacation cottages). They’re completely waterless. And don’t worry; when you lift up the lid, you don’t see what’s composting in the tray. These toilets have a cover that separate your eyes, and your bum, from what’s being broken down below.

Another perk to these system is that they require no winterization. If you live in a cold climate, then you don’t ever have to worry about your pipes freezing.

Photo courtesy of

Batch systems may only have one tray for composting, or they may have several depending on which model you choose. And how often you have to empty these trays largely depends on how much you use the toilet, and how many people are in your household.

Continual process systems are designed for larger households (pic on right). These can handle more waste, and are perfect if you have a basement or your house is built above ground.

The picture on right is part of a waterless system by Envirolet. It can handle waste from up to 10 people per day, and only has to be emptied every six months or so.

Low Water Systems

Some companies, such as Envirolet, also make low water composting toilets. If you squirm at the thought of letting your waste just go down a hole, then you might want to consider these systems.

They work on the same design as the continual process systems in the sense that there is a large composting unit outside the home. But the difference is that your waste is “flushed” down with a mere pint of water. With the Envirolet system, you can install up to three low flush toilets on one line.

Can I Put Toilet Paper Down There?

As far as I can tell, you can put unbleached toilet paper into composting toilets. But, feminine hygiene products are a no-no.

How Much Do Composting Toilets Cost?

Composting toilets run anywhere from $500 to $2,000. Just like anything else, you’ve got your choices. Every brand and maker is different, and they’ve all got different bells and whistles.

Of course, you could try making your own for far less money. Many people do (see the Resources section below…)

Composting Toilet Resources

These vendors make good composting toilets:

And here’s some resources if you want to try making your own…

Last Word…

I never, ever thought I would actually have “feelings” for a toilet, but I truly love these systems. You can bet I’m incorporating a waterless compost toilet into our micro home design, and I can’t wait to get one!

If any of you currently have a composting toilet, I’d love love love to hear about your experience. And, I’m sure other readers would too, so please write in and share!

Republishing Policy:

Like this post? Great! You’re welcome to reprint anything that’s posted on, as long as you link back to the original article. Please see my Republishing Policy for more information.

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Aya @ Thrive February 18, 2009 at 2:34 pm

That’s pretty cool, but I’m assuming this only works if you live in a house and not an apartment? It’s so hard to go green living in the city, even though the city needs to work on being green the most considering how un-green our environment is compared to the suburbs.

I do recall at one point, the apartment I used to live in went through a whole installation of eco-toilets that used less water. Ironically, you had to flush more than once because there was so little water used. How intuitive… I wonder what options we have without having the freedom to swap toilets to cool green ones.

heather February 18, 2009 at 2:39 pm

Hi Aya,

Thanks for bringing that to my attention; I really should put that in the article.

The waterless self-contained system would be perfect for small spaces, but you could only modify your toilet if you owned the apartment versus renting.

As far as green toilet strategies for apartment living, that’s a toughy. You could always go with the “If it’s yellow let it mellow” philosophy I guess!


Thanks so much for writing in!

Andrea Paulinelli February 19, 2009 at 5:39 am

If a composting toilet isn’t your thing, you can always opt for a Dual Flush toilet to save about 40% of water compared to a standard 1.6 gpf model.Caroma toilets offer a patented dual flush technology consisting of a 0.8 Gal flush for liquid waste and a 1.6 Gal flush for solids. On an average of 5 uses a day (4 liquid/ 1 solid) a Caroma Dual Flush toilet uses an average of 0.96 gallons per flush. The new Sydney Smart uses only 1.28 and 0.8 gpf, that is an average of 0.89 gallons per flush. This is the lowest water consumption of any toilet available in the US. Caroma, an Australian company set the standard by giving the world its first successful two button dual flush system in the nineteen eighties and has since perfected the technology. Also, with a full 3.5″ trapway, these toilets virtually never clog. All of Caroma’s toilets are on the list of WaterSense labeled HET’s and also qualify for several toilet rebate programs available in the US. Please visit my blog to learn more or go to to learn where you can find Caroma toilets locally. Visit to see how we flush potatoes with 0.8 gallons of water, meant for liquids only. Best regards, Andrea Paulinelli

Miles February 19, 2009 at 12:41 pm

Thank you for the writeup on composting toilets. An alternative for apartment dwellers is the “High Efficiency Toilet,” which uses no more than 1.48 gallons per flush (gpf). High efficiency toilets are different from standard 1.6 gpf toilets in that they are tested and shown to actually flush effectively…no need to double flush as Aya experienced in her comments above.

For the millions of American families that depend upon septic tanks and are not ready to switch to composting toilets, the important thing to remember is that septic tanks need regular pumping in order to continue to work properly. You can find a lot of information about this, including a recommended pumping schedule, at

tami turner March 4, 2009 at 5:44 pm

i’m currently haveing a problem with the county in which i live, i live in a house that was built in1860 way out in the country over my septic systen, (none)they have not disclosed wether or not an enviormentaly friendly toilet . Mariposa county, california, is harrassing my 80 year old father over this please help me convince them that this is a safe alturnative

heather March 4, 2009 at 6:38 pm

Hi Tami,

Thanks for writing in! I’m sorry you’re having trouble; it’s difficult sometimes to change people’s way of thinking, especially when they have preconceived ideas about certain issues.

My only piece of advice is to Google “composting toilets” and compile a list of resources to give to your county. Composting toilets are entirely safe, and giving them hard evidence to this fact is the best way to prove your case.

Best of luck, and please keep us updated on what happens!

Eileen March 13, 2009 at 11:21 am

Can anyone tell me if any type of peat moss can be used in the compost toilet, or only the brand sold by the company toilet was bought from. I have a Sun Mar, and the price to have the mix sent is $15.00s&h, above the cost of the mix. So I thought perhaps I could just purchase peat moss from a local greenery. Is it the same kind of stuff? any help is appreciated. I have searched endlessly online for this question, but no answer as of yet. Thanks
[email protected]

heather March 13, 2009 at 11:42 am

Hi Eileen,

Gosh, I wish I knew the answer to that one!

Have you tried asking the company? They might automatically say you have to buy theirs, just so they make money, but being a green company they might tell the truth. You never know!

Good luck!

Michele March 27, 2009 at 5:04 am

I have a composting toilet and I *love* it! It’s a custom-made system, very easy to use and completely odorless. I wasn’t terribly excited about the prospect at the beginning, but the house I recently moved to came with this toilet, so there wasn’t much choice. I’m now a total convert and would really recommend giving them a try.

Heather, I’m planning to blog post about our composting toilet experience soon (including the actual composting part–next time we empty it) and I’d love to link to this article. It’s really informative and I think you’ve done a great job covering the essentials.

Eileen, I’m not sure if you can use peat moss or not (I agree you should ask the manufacturer), but peat moss is not the most environmentally sound of materials, so you might want to avoid using it even if you can.

heather March 27, 2009 at 5:10 am

Hi Michele,

I would LOVE to read your article when you get it posted! I’ve fallen in love with the whole idea of composting toilets, and would love to see what it’s like to actually empty one. I would definitely re-link back to the article from this one to give readers that additional resource to see.

I love your blog btw; you have some great pics up!

Thanks so much for writing in.

Michele April 2, 2009 at 3:39 am

Hi again Heather!

Here’s the permalink to the post:

I really believe that composting toilets are the way forward and I’m always very happy to hear from you or any one else who would like to discuss them. It’s wonderful that you’d like to get one for your future home. Have you given much thought to the type of system you’ll install?

Looking forward to hearing more!

heather April 2, 2009 at 6:13 am


Your post is fantastic, and I love the picture of your composting toilet! It looks nothing like the ones I’ve seen over here in the US.

I loved what you said here:

“Conventional toilets are such an expected and ordinary part of life in the West that it’s no wonder we seldom question the logic of defecating into gallons of precious drinking water every day. We should.”

Truer words have never been spoken. Thanks for the great link! Readers, please go check out Michele’s blog, A House Called Nut ( It’s very refreshing, and there are wonderful pictures up on each post.

Woodsman May 8, 2010 at 3:03 pm

Hi everyone, well I think we have the best composting/earth toilet for the money only $200 and it works far faster and simpler than most leading brands! We also have lots of other off grid or sustainable products as well, Thanks let us know what you think~

Septic tank repairs fan October 15, 2012 at 5:23 pm

I thought about getting one of these toilets once when my tank broke, but I decided to just have septic tank repairs done instead. It was much easier for me than buying a whole new toilet and installing it. How do they keep it from smelling all the time?

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