The Ins and Outs of a Composting Toilet

Kirsten Seeto
Jun 2, 2018 · 8 min read

I’ve wanted to write a post on this pretty much since I started using the composting toilet. People online were insisting it wouldn’t smell and, to be honest, I really couldn’t see how this was possible without chemicals but it really is true. It’s not completely hassle-free but given the benefit of being able to set up wherever you want without access to sewerage plumbing its pretty incredible. It’s one of the things I stressed about the most in considering how living tiny would work out. Turns out its one of the easiest aspects of tiny living.

I purchased the EcoLet NE Separera, from EcoFlo. The product link is here but I think this model supersedes mine as mine plugs into mains power for the fan. It’s ridiculously expensive for what it is — some moulded plastic and a fan that could have come out of a 1980’s computer. But I shelled out the cash for its compliance certification and I’m guessing that’s what I’m paying for. If you weren’t worried about your local council you could totally make one yourself for a tenth of the price. But I was worried so I bought one with certification for the most number of states, including the state I knew I was going to start in (Victoria).

It’s essentially a plastic shell that looks like a toilet, with a fan and 2 chambers inside, hence the “separera” part of the name. This type of toilet separates the solids and the liquids. I liked the idea of this so that I didn’t end up dealing with a big sqidgey pile of sewerage when it was full. It’s important to keep the deposits separate in this set-up. Some liquid can go into the solids chamber but you must keep the solids out of the liquids chamber. The liquid drains out a hose which I have plumbed externally. This can either be drained into a separate chamber or plumbed to water your favourite tree. I’ve done both but remembering to empty the chamber is a complete pain so I’ve now plumbed to water a tree. I always follow-up any liquid deposit with a cup of water to dilute the tree deposit and also to keep everything relatively clean. Once a week I pour boiling water down it to stop any salts building up. You must not let any solids into that chamber because urine is fine for a tree but faeces is not. The solids need to be treated. This is really not a problem so long as you position yourself properly on the toilet. As a girl, I always sit down so this is something I keep in mind every time. If you are a guy and want to stand up I think splash-back is going to be a problem. The liquids chamber is quite shallow as it’s essentially a wide funnel. The instructions say you must sit, but in my experience men would rather pee outside than sit down. I don’t understand it but that’s a conversation for another time :) I’m not sure if it’s just me but getting a stream of liquid with “equipment” that you cannot control the exact direction with is not quite fool-proof. To be honest, I don’t think it matters that much, but it bothers me a little that not all the liquid ends up in the right chamber.

When you make a solids deposit you always scoop some humus in after. Humus is

20% fine grade peat moss and 80% untreated wood shavings. I read that I could probably make this mix myself but after making several enquiries to local hardware and nurseries I decided it was easier just to buy it from the toilet supplier. I was also unsure I was operating the toilet properly and didn’t want a home-made humus mix to be a source of conjecture. It’s not that expensive anyway — it looks like the 45 litres I ordered at the end of last year will last me 12 months. For $50 that’s not going to break the bank. After the scoop of humus you then spray an enzyme (also purchased from the toilet supplier) to help the process along. You can also use the enzyme spray to clean the toilet.


I make sure I use 1-ply toilet paper because the thinner the paper, the quicker it will decompose and the less space it takes up in the chamber. It takes some getting used to 1-ply paper when you’ve been used to 3-ply for so long. But it’s totally possible and you feel better not wasting so much paper!


The toilet has a fan that runs 24/7. It plugs into a power point (important to design the space with this nearby!) and uses hardly any power. The ventilation pipe needs to finish above your roofline so this needs to be taken into account when designing your tiny house. I went to the trouble of plumbing the ventilation pipe into my walls and ceiling so that it pops out just below the apex of my roof. I needed to put a couple of bends in it so it didn’t end up right next to my bedroom skylight (figured any smells might ruin those summer nights under the stars). Whilst this troubled me in terms of affecting the efficiency of the ventilation, the manufacturer assured me what I had done sounded fine and it hasn’t created any issues to date.

So for the first month when I was living in it in Sydney, where there were no livestock around, it worked perfectly without any issues. No smells, no insects. Then I moved it to its new home in a country town, right next to a paddock of chestnut trees. Sometimes the owner of this adjacent property puts his cattle in it and this is when I started having issues with insects. I started to notice little tiny vinegar flies. I’m not sure what their real name is but I think some people call them gnats. They were hanging out in the solids chamber and getting rid of them became difficult. I googled the issue and there were suggestions that the pile was too dry, so I started adding a cup of water every day. No effect. I called the manufacturer and they told me to sprinkle tomato dust in the pile. No effect. By now I could see larvae in the pile and this was grossing me out. I was also stressing that this meant I was not operating it correctly and I was going to screw the whole thing up. Being independent from sewerage was crucial to the whole set-up! So I started googling again and found a post from someone who recommended diatomaceous earth. This is a natural product made from siliceous sedimentary rock that is crumbled into a fine powder. People use it to bring bed-bugs under control and this blogger stated they had used it to get an insect problem in their composting toilet under control so I gave it a go. It’s not that easy to find and its expensive ($30 a can!) but it did the job. I used an aerosol version as I figured that would be easiest to apply. That took about a week to get the larvae under control. In the meantime I also used an automatic spray to keep the hatched flies under control. When there was an outbreak I’d need to keep the bathroom door closed so I could contain the insects to the bathroom and allow the automatic spray a confined space to be effective. Using both of these measures brought the problem under control in about 10 days. I’ve only had 2 outbreaks in 6 months and both were during the summer months when the livestock was around.

When the solids chamber is full you simply take the top half of the toilet off and pull the chamber out by its handle. One chamber lasts me about 2–3 months. I’m living here at least 75% of the time and am the only person using it. They suggest you take the full chamber and go leave it to mature outside for 12 months but with only 2 chambers that leaves me with an issue. So I bought a composting bin from Bunnings and empty the chamber into that when I need an empty chamber. They say to leave the contents in the chamber as long as possible so a full chamber sits nearby ready to empty into the main composting bin when I need an empty chamber. I’ve emptied 2 chambers in the larger composting bin and they already looked a lot like compost and not much like poo. The paper seems to take longer to decompose.

I’ve had the power off for 24 hours at a time to move the house which meant the ventilation fan had been off. Close to the toilet it starts to smell a little like the enzyme spray (a kind of chemical smell) but never did it smell like poo and never did the smell stray far from the bathroom. I can say I have never smelled the toilet in the 7 months I’ve been using it.

So apart from the insect problem, its been very easy to use. Using a composting toilet really makes you think about some of the bad habits we have fallen into by simply expanding on waste treatment methods as our population grows without really thinking about whether it’s the right method any more. To be using so much drinking-grade water to flush after every deposit seems ludicrous, and then we create sewerage that is expensive to treat and potentially harmful to the environment. Treating excrement the way nature intended to is not only extremely satisfying, but also cheap and, if done correctly, beneficial to your local environment. If you’ve been considering a composting toilet, read up on what is involved and do it. This book is a great starter to that journey -


Originally published at My Journey into Tiny.

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