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

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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.

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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!

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