The simplest, cheapest and easiest compost toilet

Maybe you’re thinking about buying or building a compost toilet, but you’re not sure if you’re ready to make the leap and part with a lump of cash or spend a lot of time making something.

What if you want to dip your toe in the waterless world of compost toilets and humanure to see if it will work for you, or simply don’t have the budget just yet for that lovely, shiny, all-singing compost toilet.

Can you get started with a compost toilet, at really low cost?

Yes, I think you can and it’ll cost you almost nothing! Plus it will give you some practical insights and experience, and can help you determine the right way to move onwards and upwards (if you want) and not make costly mistakes that you’ll later regret. Before you get too excited though, there are some compromises and I’ll talk about these further on.

Look at the whole system, not just the toilet

I want to start by saying that most compost toilets are part of a composting system. They’re the collection side of the coin, with your compost bin being the other, equally important side where the composting actually takes place. Unless you’re looking at toilets with underground chambers and the like, you probably won’t have a proper ‘composting toilet‘, in reality what you’ve got is a compost toilet, dry toilet or waterless toilet.

Note the missing ‘ing’ on compost vs composting- that’s important!

Composting as a process needs CARBON, MOISTURE, OXYGEN, and NITROGEN – the carbon usually comes from the cover material (such as wood shavings or sawdust), and the nitrogen from the faeces and urine. Oxygen (air) can be added through agitation (which mixes things up and gets air in there) or even by adding a coarser carbon material which traps air.

Rather than complicate things, I prefer to just use the toilet for collection and do the actual composting outside in a compost bin – it also means the toilet can be very compact and easily moved. It’s capacity is however limited and it will need emptying regularly – if this is an issue for you, then you should look at a toilet based around a urine separator.

Keeping it really simple

Simple is good. Simple is understandable. Simple is fixable without having to get ‘experts’ in. The simplest compost toilet is essentially a bucket with a toilet seat and lid over it. You might already have a bucket – a 25 litre container (5 gallon) is ideal, but you can use a smaller one.

I managed to find a cheap camping toilet online from a UK outdoor adventure retailer (www.millets.co.uk) – it was on offer and reduced to £15 with a further 15% off. With shipping, I ended up paying under £16. However, since buying it, the price has gone back up.

If I was being critical about my camping toilet, I’d have liked a bit more capacity, to have it a bit taller, and to have a full-sized toilet seat, but as an experiment (or just to take away camping, which is the original design intention) it’s fine.

Getting started – the base layer

I chose not to line my bucket, but you can use biodegradable bags if you want. Personally, I think the bags are an additional cost and hassle that I can do without, but I appreciate that some people would like to think that the inside of the container is clean between each empty.

You’ll need a good base layer of a carbon-rich material – this is to act as a ‘sponge’ or soak to absorb up any liquids that get down to the bottom. So far, I’ve experimented with wood-based cat litter pellets, wood shavings and sawdust (from cutting firewood with a chainsaw) as the base layer. Add a good 3cm (1 inch) layer.

Choose your cover

Your choice of cover material is really important in an all-in-one bucket toilet. The cover should be a carbon-based material (because the wee and poo have more nitrogen and we need a good balance to make excellent compost) which means it’s probably best to use a wood-based cover.

Because you’re not separating the wee from the poo in this simple style of compost toilet, you need it to be a slightly absorbent material, ideally with a bit of a ‘rough’ structure/texture so that oxygen is maintained/trapped in the contents. I started off with wood-based cat litter pellets, first emptying some into another container and adding a little bit of water to ‘fluff them up’. These worked really well, but the pellets are quite expensive.

At my local ‘countryside’ store, they have a similar product for horse bedding that’s much cheaper, but I’m not sure that it’s as fine as the cat litter wood pellets. Again, I’ll have to experiment one day and try them.

After this, I moved onto just fine wood shavings (sold as pet bedding) – these were inexpensive but I’d rate them only as ‘OK’. I found that you needed to add a lot of it to get the odour control I was happy with. A friend of mine suggested leaving the shavings outside for a while to ‘weather’ – this will get the good bacteria into them and this should improve their odour control. Fresh out of the bag, wood shavings are bone dry and therefore quite inert – you might think dry is good, but you actually need some bacteria in there and they need moisture to keep them working.

My final test, and the one I’m sticking with because it’s brilliant, is sawdust from a chainsaw. I’d heard from other people that this stuff is ‘gold’ for compost toilet cover material because it’s already got the ‘good’ bacteria within it (from the living tree etc). This stuff really is a game changer – you don’t need to use much, it was free (for me), and it just works incredibly well as a biofilter (locks the odours in because the bacteria get to work quickly).

The idea is that after every visit, you add some cover material. If you’ve just had a wee, it only needs a little, but if you’ve done a poo, then you might need a couple of scoops. Ensure everything has been covered up, including toilet paper if you’ve used it.

I have a container with lid by my compost toilet and inside is a plastic scoop which keeps it handy and easy to use.

Do you dare to stir?

Agitating the contents will really help with odour control, but it might be a step too far for some people, which I completely understand. I know of quite a few compost toilet users who have a ‘poo stick’ in a bag that they use to stir the bucket every day or so. It’s also useful to ‘knock the tops off the mountains’!

But if that’s too much for you, don’t worry about it!

How quick will it fill up?

It depends. My camping toilet is probably around 20 litres and for one person using it all the time, it’ll fill up in under a week. I stretch mine out to lasting around 10 days, but that’s because I’m urinating elsewhere a lot of the time. Urine equates to around 80% of the volume of your excretions.

Doesn’t it smell bad?

No. Once you get the cover amount and type right (and if you’re unsure, just add more) it won’t smell. When you first open the toilet seat, there is sometimes an ‘earthy’ odour, but that soon goes.

If people tell you that you must separate the liquids from the solids in order to stop smells, they are wrong! Separating toilets have their place – they can make it easier to control odours, and they fill up more slowly, but you have to sit down, and in the correct position for it to work and not everyone can do this. The key is the cover material.

Do you put used loo paper in there?

I do, for convenience. There’s an argument that loo paper takes up space, inhibits stirring (if you do that) but it’s just convenient so that’s what I do. Some people have a small separate bin for used paper, especially ‘wee’ wipes, which is then burned or disposed of later. If you are happy to do that, brilliant, but it can be a step too far for some people, so don’t worry about it.

Composting

Composting is huge topic and no doubt will be covered elsewhere in detail. I have started with on old plastic dustbin – drilling holes in the base and some in the sides allows excess liquid to drain away and lets some air in (and worms in too).

I plan to agitate the contents from time to time, and check it’s not too dry (adding water or urine where needed). Beyond that, I’ll start harvesting the compost after twelve months.

From previous work with humanure compost, I know that the result looks like any other homemade compost and doesn’t have any visual or odour clues about it’s origin.

When I’ve emptied my bucket, it’s usually fairly clean. I rinse it and pour the rinse water onto the compost pile.

My verdict?

Looking at the positive aspects of this, I would say I love the simplicity, the low price and the relative ease of maintenance (this is used just by me). It doesn’t use any electricity and the only ongoing cost might be the cover material.

• simple
• low cost (potentially free)
• ease of use
• ease of maintenance
• completely off-grid – no electricity needed

The negatives are that it’s quite ‘hands on’ – not in a dirty sense, but it won’t suit everyone. Depending on the number of users, you’ll be emptying the bucket regularly, more often than you would with a urine-separating toilet and you have to keep an eye on how full it is because, especially with a small container, it goes from being useable to unusable quite rapidly!

You’ll also need a fair amount of space to do the final composting – not everyone has this space, so factor this in. And finally, the containers can get quite heavy, so again think about this – how far is your compost area from the toilet?

My compost toilet is in my garden shed, but the portability of it means that in the winter (when I don’t want to have walk down the garden in the cold, rain or snow), I move it into the garage. Having sorted out the best cover material, I’m now confident enough that it doesn’t smell, that I could move it into the house with no ill effects.

The particular toilet I purchased is fine for occasional use, but the seat and hole is smaller than a regular toilet and after a while, that got annoying. The capacity was also a limiting factor – at about 2/3rds full, my ‘bits’ start to get very close to the contents!

This simple toilet is essentially the type championed by Joe Jenkins (author of the Humanure Handbook) – you can find out more on his website https://humanurehandbook.com/

If you’re concerned about hygiene the safety of composting, don’t worry. The simple humanure method of collecting and composting has been subject to scientific scrutiny by the aforementioned Joe Jenkins. In his book, the Humanure Handbook, you’ll find all the facts behind this method of composting that will ensure all pathogens and nasties are safely and completely dealt with by the process.

So what are your thoughts? Would this be something you’d try? Is it too basic for you or is there too much work involved? Have you tried something like this? Let us know in the comments area below!