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When “Eww” Turns to “Ooh!”

Photos © Craig Mackintosh

You’ve heard the Zaytuna Farm composting loo story before, but since this is the first time I’ve personally seen ‘the great chamber changeover’ take place myself, during one of my own visits, I thought I’d share the tale once more.

The PRI’s Zaytuna Farm composting toilet setup utilises the Farralone (230kb PDF) dual-chamber system. It’s not a complicated affair, and it works a treat. For the… er… end user, utilising the system is as easy as making your delivery, and following that up with a correspondingly appropriate sized scattering of carbonaceous material, like sawdust. The chamber then piles up with layers of nitrogen-rich human waste and carbon. Anyone who understands the ABCs of composting knows what the result of this will be. And, should the loo ever become a little smelly, it’s simply because you’ve been adding insufficient amounts of carbon (sawdust, dry leaves, etc.) — enlarging the carbon additions will promptly address the issue.

When a chamber can’t take any more ‘contributions’, to use Geoff’s terminology, it’s closed up and left to sit for a few months. Our little microbial friends work quietly and busily over this period, working magic with our muck, in a way that only they know how, while deposits continue in the adjacent chamber.

The interesting thing is, no matter how much you emphasise to students and interns how well the system works, when the day comes to actually empty out a full chamber — even when having been left to ‘mature’ for a full three months — the lead-up to the event is always accompanied by a relatively high degree of trepidation. When the day arrives, and Geoff reaches to open the chamber door, students tend to stand back at a ‘safe distance’, wrinkling their noses in expectation, and almost cringing as the door swings open….

But then, mental "eww"s turn into verbal "ooh"s, and the dreaded moment turns into a non-event….

Geoff promptly grabs a shovel, and leads the way — lifting out shovel after
shovel of nice, crumbly looking material — while the students begin to edge closer.

The compost is emptied onto a trailer, before being taken to get spread thin and
layered with mulch. After resting on and under mulch for a while it is then
hot-composted, before
finally getting utilised on the farm.

After seeing the rather benign looking material, and Geoff’s indifference about the situation, the students begin to throw caution to the wind and jostle to be next on the end of the shovel. (I mean, who wants to be last?)

At Zaytuna farm, in many ways, it’s incredibly satisfying to know that our most basic needs are met in a passive, carbon neutral (even positive) way, through sensible, appropriate permaculture design. This is especially true when it comes to that most maligned of human by-products — a material we normally, and strangely, mix with pure, clean water, so as to enable us to transfer it into a pathogen-rich, centralised network, before sending it out, at great expense, to pollute our oceans, or before we (insanely) invest enormous amounts of energy trying to purify again…. The other big ‘strategy’ is to simply let it pile up underground, to slowly leach into our landscape and water tables.

When you consider that clean drinking water is of more value than gold to many of the world’s inhabitants, it should be regarded as obscene to be crapping in it!

If this dual-chamber system can handle the many contributions from a very steady stream of students and interns, it can so much the more handle those from a typical home situation.

At the PRI’s Zaytuna Farm our most basic human functions not only leave precious water completely untainted, but another significant plus is that soils are regenerated through the subsequent cycling of nutrients and minerals. Top of the critical nutrient list is phosphorus — essential for all plant and animal life, and a growing concern worldwide. If we harness the potential of nutrient cycling through composting toilets, then the Peak Phosphorus dilemma would become a non-issue.

When I consider the simplicity and logic of such a system at this, the more absurd our massively expensive municipal installations seem.

Talk about turning a problem into a solution!


  1. Oh! How I do love humanure systems! We have been humanure-ing now for about twenty years and I wouldn’t have it any other way! This is the first year that we have been making “lasagne” mulch and our precious compost pile came in very handy.

  2. Hi Craig,

    Good to see that they are utilising such a valuable resource there, although you wouldn’t expect anything different.

    When people visit here they sometimes ask if there is anything they can bring. I say, “bring poo!”.

    It’s also fun to get people to have a look into the worm farm which processes the human wastes here because: a) it just looks like soil; and b) it has only a minor humus smell – much less so than composting toilets.

    Peoples yuk factor is disproportionate to the resource.

    The whole phosphate cycle in agriculture is one of lost opportunity and as such is short term and won’t last out our lifetimes.



  3. I would love to see this or any other option available to householders in Australia.

    The driest continent in the world & it’s hooked up to the water supply! And to add insult to injury, water charges are set to increase by 30% in July 2012.All that wasted water & materials..I’d have one installed in my own home tomorow if i could.

  4. Hi Craig,
    I just want to share some Asian way of disposing our nature’s call. Normally, we use water to wash off instead of just toilet paper. Will this make the end results more watery?

  5. What a great post and photos! Can’t wait to see more posts from your trip, as a permaculture journalist you are probably the world’s best!

    Again I’ll encourage the PRI-institute to give Craig an assistant to help him with editing incoming articles, so that Craig himself can free more of his time for permaculture journalism in world class!

    I should hate to see Craig being hijacked by BBC or CNN because they can support him with more assistance and resources for travelling and so on. Craig is unique, and thanks for giving him the opportunity for this travel in the permaculture world!

  6. Seah Choon Siang – the toilet at zaytuna had a pipe that goes into a reed bed so any extra fluids were taken away from the main pile and processed. so no problems without toilet paper.

  7. Concerning the phosphate cycle, it’s actually interesting to see the other side of the coin – i.e. what we are going to likely get if we fail to raise sufficient awareness about embarrassingly simple solutions.

    In order to understand this, one has to realize three things:

    1. Much of the phosphate applied by industrial agricultural practices becomes insoluble quite soon. In the west, we have been massively enriching agricultural soils with phosphorous in a form that’s mostly inaccessible by plants, by over-applying so much of it that the soluble fraction of that directly feeds the plants.

    2. Suppose you are a professor in some life sciences related discipline. You have become a specialist in a quite narrowly defined field. You know a lot about plant metabolism, and if you haven’t got that clue already anyway, you will soon realize that it is very important for you to work on problems perceived as relevant in order for your papers to get cited, and your research grant applications to receive sufficiently favourable reviews (by other narrowly specialized experts) to get funded. When submitting research grant applications, it is of course massively important for you to play to your strengths, emphasize your experience, why you and nobody else but you can and should do that type of work (because only you have that very deep understanding of the key biochemical processes in plant metabolism). So… what kind of grant application will you write? “I’ll tell people what already Liebig tried to tell them – i.e. to crap in a bucket – before he set out, as a sort-of stopgap measure – to come up with industrial fertilizers”, or “I will employ my deep understanding of genetic engineering/synthetic biology/whatever strange magic to research methods to engineer plants/funghi/bacteria/little green bugs to tap into and mine that phosphate reservoir to postpone having to deal with the actual problem for another decade or two” – your guess. Of course, your livelihood depends on bringing in such grants, and you have to use the expertise that discerns you from everybody else in the field as your most important capital.

    3. If you are e.g. a political party wanting to sell a solution to people as “progress” and as “incredibly important research essential to our very survival” – well, guess what sells better?

    I hope society will realize soon that there is such a thing as insanely stupid outcomes of the idea of hitting a problem with excessive amounts of human cleverness. At the moment, ideas such as this are met with an incredulous “but that’s not (hi-tech) progress” attitude. I’d say it is indeed progress – and I wonder how society got so programmed to believe that “if it’s not over-engineered tech, it’s no good”.

    But hey – maybe the problem is just that compost toilets lack “the blinkenlicht”. That’s easy to fix then.

  8. Hi Rebecca,

    The option to compost or worm farm most forms of organic matter is available to most people in Australia. Even apartment dwellers can get in on the act through either really careful monitoring of their chosen system or by using a communal system in a community garden. Your end product – compost, not foul smelling gunk mind you – could even be placed down at the local garden or park. If you are uncomfortable about being seen doing this, how about placing it there at night, guerrilla gardening style? The trees and garden beds can always use a good feeding.

    Regards. Chris

  9. Funny this should come up in my morning web surfing, because I used this toilet just three days ago. And I found it smelly. We have a Nature Loo inside our house (unlike this one whose door faces the outside) and is in fact “ensuite” to our bedroom….. and I can tell you we would never put up with odours this bad in our house. I’m wondering if this loo even has a fan?

  10. Hi Mike

    As mentioned, whether the toilet smells or not is really dependent on the people using it. Here there are many students going through, and if some of them are a little lazy in ‘flushing’ (adding sufficient carbon afterwards), then its obvious what the result will be. I’ve noticed it smelling on occasion only, and when it does, I just add more carbon, and the issue (again, as above) goes away.

    In a home situation, where your family are all well versed on how to best manage the toilet (it’s not rocket science…), this is a non-issue. We just don’t have control over the behaviour of all the students here, so don’t take your isolated experience as being typical of these types of systems. Students are here to learn, and this is all part of the learning curve.

  11. Funny you say that mike because i used the toilet, the one pictured in the photo above for 2 weeks, as did 30 other people and there was no smell complaints from anyone.

  12. Craig,

    ah… if the outhouse only became as iconic as a certain blue police box…

    But, well, maybe that’s indeed not that impossible to achieve (for a humoristic genius, that is).

  13. Hi Morissey…. perhaps the users thought it was “normal” for such a toilet to smell if they were new to the idea. My question regarding a fan wasn’t answered either… does it have one?

    Our toilet BTW doesn’t need sawdust because it’s a urine diverter variety. Sawdust is usually added to a compost toilet to absorb urine, plus only wet shit smells, and if it dries out faster by using a fan and not being urinated on, then odours are inevitably absent. Just my 2 cents.

  14. Hi Mike. Sorry, been busy. Yes, the system does have a solar powered fan (well, it’s solar powered because the whole place is off-grid and powered by solar). I still don’t note any smell…

  15. As your article shows with the use of the words human waste, the idea of humanure or shit as ‘waste’ is still a strongly ingrained and false cultural belief. Great article.

    In the caption of the photograph with Goeff dumping a wheelbarrow load, you mention hot-composting. What happens to the thermophlic bacteria stage inside the chambers of your system? Why do you have to hot compost it (?again?) and move it around so many times before you can finally use it? When life and social circumstances in my places of living have allowed, i have used a bucket system which gets directly dumped into the final compost pile which can be used one year after the compost has been closed and is put in ‘curing’ mode. So i am familiar with this method which is mostly based on Joe Jenkins’ works.

  16. just so i understand this properly – this humanure is being used as compost for food or just trees and non edibles – i thought that humanure had pathogens that made it unwise to use on food?

  17. When I was a little girl I remember having outside toilet and it was emptied by farmers for their compost heaps. To us it was very natural and nothing ‘odd’ about it. In winter time when temperature was over -20C you learn to do your ‘business’ very quickly though :-)

  18. After a recent experience I’ve been looking for information on humanure systems, I happened on this great site. Though I may have arrived very late to this thread trust me, I will be building one or other variety of composting toilet with some degree of urgency!

    Living out in the sticks, we have a 10,000 gallon cess pool tank from which, raw sewage is pumped out into a commercial tanker periodically (at great expense) with the contents being taken to their bio-digester unit.. So far, so good, provided that you can get them to actually turn up and pump out.

    After the latest prolonged series of delays, no-shows and excuses, all the drains and inspection chambers leading down to the tank, had filled up with the ‘inevitable’, with the liquid component steadily draining down the system and seeping out past the tank lid …. leaving all the solids behind.

    A neighbouring farmer kindly pumped out with his small slurry tanker as deep as his hose would go, leaving just under a ‘wellies depth’ remaining in the bottom of the tank. We hoped that emptying the tank would free up the backlog but nope, that would’ve been way too easy.

    The closest inspection chamber cover has not been off in the 30 years we have been here and might as well have been welded shut – nothing short of semtex was going to shift it. We tried for hours to clear the blockage with drain rods from the next chamber up the line but got nowhere. Lacking the kind of bank balance needed to employ the likes of ‘Dynarob’, the only thing left was to try rodding from the bottom end up ….. ie from inside the tank.

    After gearing up a small bouncy castle fan and some ducting for ventilation, roping up and donning my longest wellies, I squeezed through the tiny access hatch and reluctantly descended the slippery and corroded steel ladder into the pit of sh*t and the rods were lowered in to me.
    With about 25mm of ‘freeboard’ to the top of my wellies, and standing in all the ‘best material’ that had collected at the bottom of the tank, I set about the task of rodding with, I must say, some degree of trepidation though clearly not entirely comprehending the sheer power of the hydraulic head on the 3 metre fall and the volume of 40 metres of 150mm drain and 2 pretty deep inspection chambers – all full and rarin’ to go!
    I’m guessing by now you’re way ahead of me ;-)

    My impending doom was heralded by a thunderous roar followed by what can only be described as an obnoxious ‘brownout’as a six inch bore of ‘material’ shot straight across the tank with unbelievable force. On hitting the back wall, to say the very least ‘it spread itself about a bit’. I had absolutely nowhere to go and I thought it would never end!

    Factor in the indignity of stripping stark b*ll*ck naked in the yard, being sadistically hosed down by the wife before eventually and most reluctantly, being allowed in to shower, and I hope you will understand my enthusiasm to try a more hygienic, less smelly and gentler form of waste disposal.

    hey ho! there’s always a bright side … at least I got the drains cleared and I did get one welly back :-))

    Dave P

    ps. Mike S – trust me, you ain’t smelled nothin yet ;-)

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