Should I switch to a compost toilet?

Switch to a compost toilet

Are you thinking of buying, building or improvising a compost toilet? Waterless compost toilets are not only a great solution for off-grid lifestyles, they’re also great for the environment. Plus, they’re increasingly popular. Which is just as well, since, according to Waterwise, in Britain we flush away – wait for it – 2 billion litres of fresh water every day.

Oh. Dear.

The good news is that more and more manufacturers are responding to demand by producing increasingly efficient, user-friendly and affordable compost toilets both for both land and vehicular use.

But I need to tell you: the world of compost toilets is deep and complex. Yes, much like their contents.

Where are the pipes though

When I first moved onto my boat I searched online for boat-suitable toilets – I’ve already talked about my chemical atrocity here – and immediately found the Simploo. Now, the Simploo looked to be exactly what I was looking for. That is to say, it looked like a toilet. Simple. But what followed was a series of very confused (and confusing) emails to a nice lady called Kate, who tried explaining the toilet to me very clearly and carefully.

I kept not understanding.

You see, at that stage I couldn’t really comprehend that a toilet could just be freestanding, basically a fancy commode. I was convinced that my existing chemical toilet was plumbed in to a complicated system of pipes and sewers (despite the fact that it was on a boat). I could not conceive that it was a self-contained unit that could just be unscrewed from the floor. Likewise I couldn’t conceive of what a compost toilet would be, could be, or should be; whether it would need to be plumbed in, how much space it would take up, or what happened to the poo. Or what happened to any part of anything.

I don’t think I’m particularly stupid (obtuse, perhaps) but such details were entirely opaque to me.

Clear as mud, as my nan used to say

I told Peter the Boatman that I wanted a compost toilet. He pulled faces and said I’d have to work out what I was going to do with ‘all the solids’.

All the what now?

‘The solids,’ he said, for the second time. It took a few stilted conversations for me to understand that all that decomposing poo has to live somewhere once you empty the toilet and until the poo has finished composting. ’Oh,’ I said, finally. This signified that I had done about as much thinking on the matter as I was capable of.

The compost toilet idea ran to seed.

But because I can’t (won’t) believe that I am the only obtuse person in the world, I’m going to share my meagre learnings with my fellow composting know-nothings. (You might also want to read the next post in this series, here…)

Here we go.

Six degrees of separation

Most compost toilet systems are based on a separating system; in other words, they separate urine from the faecal matter. If you’ve ever been to a festival then you will know well the specific aroma of the blended poo and wee. It is not good. In fact, it is poowee. It is the very same perfume you can create easily at home by collecting all your poo and wee in a bucket. After less than a day of moderate usage you will have your very own eau-de-festival, to remind yourself of those heady days of high summer.

However, if you keep the poo separate, dry and preferably buried in sawdust, I am assured it doesn’t smell at all. While I can’t yet testify to this from my own experience, as a long-term cat custodian I can confirm that stinky feline faeces are entirely neutralised when buried in wood litter. (It’s only when the cat leaves the poo carefully balanced on the surface like a sausage on mash that there’s a problem.)

It is also far easier to dispose of urine (which is generally completely sterile) than it is fresh, raw sewage. Diluted weewee can be used to fertilise plants. Apparently you can also lighten your hair with it. Some people even drink it.

Whereas you should definitely not throw fresh poo on your tomatoes. Or wear it on your head.

For vanity’s sake

Unless DIY is your thing, you will probably want an entirely self-contained toilet. In other words, everything happens under the seat. You can think of your toilet as a freestanding piece of furniture (although you may well want it bolted to the floor in case the bog topples over with you sat on it).

Beneath the toilet bowl will be at least one container. More often you’ll find two separate compartments for liquids and solids (and possibly a third for longer term composting).

Some toilets have a ‘vanity flap’, which conceals the contents beneath. Down in the hole, the poo is encouraged to dry out, either by installing a 12 volt fan or just by using sawdust or coir to mix in with the poo. Remember: dry poo means no smells. And if you’re of a certain age, you might have recollections of ghostly white dog poo that used to feature on street pavements. That bone-dry crud was scent-free too. Not that I ever got that close to it.

Not a fan

Some compost toilet systems advocate installing an electric fan in the solids container (I assume not actually ‘in’ it) to help dry out the stools more quickly. Some use a vent to the outdoors to help any fresh poo smells escape. I’m told this isn’t very pleasant if you happen to be strolling past on the towpath just as a deposit is being produced.

Others have an activated charcoal filter which traps and neutralises smells. However, opinion is divided on whether fans, vents and charcoal are needed. If you use sawdust (or coir) to cover your poop then the smell should already be neutralised.

Can’t I just use a bucket?

Stirring the sawdusty poo is encouraged, if not mandatory, for reasons which aren’t altogether clear to me. Liquids are collected in a separate container (also underneath the bowl) and can be disposed of responsibly. The solids will continue to break down into compost until finally they become safe to return to the environment. If you have an existing waste tank under your bed (ugh) it might be possible to divert urine from a compost toilet into that tank. Then you can savour the anticipation of pumping it out later.

By the way, it is standard for men to have to sit while peeing into urine-diverting compost toilets, because the urine separator is typically fitted at the front of the toilet bowl.

You didn’t answer my last question

If you’re considering making such an investment both of money and slurry, there are some useful resources on the web. Notably, there is the rather fabulous Facebook group ‘Compost Toilets for Boats and Off-Grid Living’ created by Colin Ives and Maria Matthews of the Kildwick compost toilet company. The group is private so your admittance will need to be approved, but there is truly… uh, well, a wellspring of information therein. Colin Ives has helpfully compiled a list of compost toilet FAQs on the Kildwick website which you can view here.

And yes, you can use a bucket. But we’ll come back to buckets, you can rest assured of that. Oh yes… we will.

Meanwhile you should probably check out the next article in this riproaring series...


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I'm Victoria. Hi.

I'm afraid I write most of the nonsense on this site, apart from the stuff written by Geoff. (Geoff is the cat in orange.)

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