The Composting Toilet

This is The Nature’s Head composting toilet…

natures head


We don’t own one of these. We wanted one, REALLY badly, but they are so painfully overpriced (£600) that we couldn’t justify it.

To put it in perspective, you can pick up a new portable chemical toilet for about £50. The designs aren’t wildly different, pretty much the same amount of material (plastic mainly), however as the demand for composting toilets is comparatively low they’ve been forced (or chosen) to whack a massive price tag on them. I think anything upwards of £200 for a toilet is kinda taking the piss (no more pee jokes, I promise) so we set out to make our own, for freeeeeee!

I trawled the internet trying to find out if it was possible to turn a chemical ‘Portaloo’ into a composting toilet. Unfortunately I couldn’t find any info so we forgot about it and went on with our terribly interesting lives. But then Rodney’s Dad happened to mention one day that he had a couple of old Portaloos in his workshop, and the idea resurfaced, like an unflushable floater (no more crappy jokes, I promise) and so we decided to give it a go.

The good news is that IT IS possible to turn a portable chemical toilet into a composting toilet. The bad news is that we ran into difficulties pretty early on and had to draft in Rodney’s Dad (a mechanical engineer) and brother (a welder/fabricator) to help make it happen. So strictly speaking it’s possible, if you’re quite handy or know someone who is. (You don’t need to be a welder or an engineer, you just need to be handier than us!)


You’re going to need:

  • A pre existing vent in your vehicle or be willing to make one
  • An electric jig saw
  • A drill
  • Industrial glue / sealant
  • A spare sheet of plastic a few mm thick
  • A sturdy piece of pipe
  • A container for the pee
  • A bucket / container for the compost
  • A 5W, 12V computer fan
  • Wire connectors (male-female or straight)
  • Crimping pliers
  • Low load 12V wire (most speaker wire is fine)
  • 3 straight connectors for the flexi pipe so it can slip onto the toilet & each side of fan
  • Larger flexi pipe approx 3 inches to house the fan and lead the rosy smells outdoors

The main bit of advice I have to offer is… do not start out with a USED chemical toilet, like we did (because we’re cheap, I mean thrifty).  We washed ours several times (unpleasant) before starting work on it, but that still wasn’t enough to undo years of stinking deposits. As soon as Rodney started sawing into the plastic, the hideous odour of raw sewage was released once more.

The internet is full of guidance on how to make a composting toilet from scratch using wood etc., which I’m sure is a lot easier, but as ours is kept in our tiny wet room we wanted it to be

  1. small (and)
  2. plastic

Here it is for your viewing pleasure. We call it… The Turtle’s Head Composting Toilet (sorry, too gross?!).


How to make it, as described by Rodney in his debut VanSpecies post!

First of all, get some gloves on. Then get your gloved hands on a super cheap – or free – second-hand chemical toilet. The toilet I used was a second-hand Thetford Portaloo, so I can only speak from experience of this type – a 2 piece toilet that separates at the middle. It stank a bit, but after being thoroughly cleaned it was fine. Please be environmentally aware and recycle if possible – ignore Jodie’s wasteful advice of buying new!

After using lots of hot water/bleach/disinfectant to clean off the fossilised excrement/ blue chemical blend, you’re ready to create your masterpiece.

1)  The first objective is to cut away excess plastic from the bottom (waste storage) half to turn it into a lidless box. This is best achieved by boring a hole and using an electric jig saw. I used a small grinder with cutting disk, which produced too much heat and led to a few drops of molten plastic hitting my ankles. Try to leave a little lip all the way around for extra support. Any hard to reach parts can be cut with a hacksaw blade and some patience.

2)  Now to the upper half- Using the jig saw cut the back half out of the toilet bowl piece and trim off any other unnecessary plastic/ pipes underneath. Leave a small lip for a lid to sit on (to be made later) and leave the front half of the toilet bowl intact as this is what you’ll eventually pee into.


3) Get a 5 litre liquid container (we used an old plastic jerrycan) for the urine part and set it on its side at the front of the base. Find a plastic container (for the compost) that fits snugly into the back of the base behind the liquid container. It should have high enough sides to store as much solid waste and compost as possible, whilst still fitting when the seat is set back on. We used a small rectangular waste paper bin with the top sawed off as it was too tall.


4) Attain a piece of pipe (metal or plastic) to drain the pee from the pan down to the 5 litre urine container, preferably with a lip at one end for ease of fixing in place. Bore a hole the diameter of the pipe at the lowest part of the remaining half bowl and glue in place with a good, reliable, strong waterproof adhesive. I used something called CT7 but I replaced after a year of use with Unibond Weatherproof which also seems to be doing the trick. Try to avoid white and clear adhesive, as the pee will stain it yellow and make your girlfriend sad.

5) Bore a hole in the 5 litre container to fit the pipe protruding from above.


6) Get a plastic sheet (a few mm thick) and cut a semi circle the correct size to act as a division/separator between the solid and liquid waste areas, so you don’t end up peeing in your compost. Glue in place both sides with the same strong adhesive.

7) Get a flexible vent pipe long enough to attach to the back of your toilet and lead smells to the outside world. I used pipe approximately 3 inches wide.

8) Attach one of the vent pipe connectors to the pre-existing hole at the back of the Thetford (if you’re using a different chemical toilet then you may have to make a hole!).

9) Buy a 2nd hand 12V computer fan from a computer repair store or Ebay. The shape of the fan will dictate how you fit it in your vent pipe- we had a square one lying around. Cut 2 squares of your plastic sheet the same size of your fan (or circles if you have a circular fan housing). Cut circles in these approximately the same diameter as the fan blades, but slightly smaller than the diameter of your vent pipe straight connectors. Glue a vent connector on to each of these 2 squares. Glue or bolt the fan in between the 2 squares, with the vent connectors facing outwards.

10) Extend the wires of the computer fan by crimping female spades onto the 2 existing wires and males to a new long piece of thin 12v wire. Connect the ends and wire into any unused switch in your vehicle or a new simple switch wired into your 12 system which can be mounted anywhere.

11) Install the fan anywhere in the vent pipe by simply cutting the pipe and sliding each cut piece over the connectors on each side of the fan.

12) Cut another semi circular piece of sheet plastic to fit as a lid for the solid waste part. Attach (screw or glue) any suitably small object to act as a handle for the lid.

13) Seal any unnecessary holes on the structure with your adhesive.


*** Important note***

As this was a prototype, I believe I could have kept a tiny bit more of the initial plastic structure for rigidity and support. This caused the top half to occasionally slip slightly over the bottom half when leaning forward on the seat. I fixed my problem by riveting some metal angle onto the bottom half to catch the top if it were to slip. This can be bolted with small bolts if you don’t have access to a riveter. 


The toilet is functional. The only thing I might change is the size of the pee container, although there isn’t much room for an increase. For two people, the container needs to be emptied daily, although pee stinks more if left to stew so a daily emptying is ok by me.


So there we are. Thanks Rodney, gripping stuff! Though you appear to have contradicted me in your very first paragraph so let’s call this your last VanSpecies post too!

Good luck to anyone attempting this nightmare of a project!!


Questions Questions Questions!

Why didn’t you just use a chemical toilet?

One of the main reasons we were against chemical toilets is that they are bad for the environment, but on a purely selfish, practical level, we weren’t willing to put up with the stench of a chemical toilet. We’ve recently discovered that you can get eco tabs for your portaloo but that they need to be emptied regularly as they also start to smell within a few days.

Does it smell?

No. Well yes, sometimes, but mostly no. The pee pot smells of pee when you come to empty it. The compost does not smell and as we have a fan in the back of the toilet leading the initial stink (of rose petals) outdoors, the van does not smell when we use the toilet. If you happen to be strolling past the van’s exterior when either of us is auditing our ass-ets, well that might be a different story.


Where do you empty it?

The pee gets poured down a drain or toilet or sprinkled on the ground (with landowner’s permission). The compost is thrown away whenever we come across a large bin.

Is that legal?

Yes, there are waste disposal laws in place that allow hospitals to dump human waste and parents to dump their babies nappies / diapers. Not only is it legal for us to put our waste in landfill, it is beneficial to the planet as our compost is bagged in biodegradable bags and becomes soil within 9 to 12 months. I’ve a hunch it will eventually become illegal to flush away waste in our precious water supply, because it’s gross…

Isn’t it all just a bit of a hassle though?

Kinda, yes. Of course it’s easier to flush away your wares and not give it a second thought. But if you live in a van there’s no getting away from the dirtier side of life. In our humble opinion it’s easier to pop a bag in a bin than it is to pour stinking, poisonous, chemical waste into our flawed sewage system. In our humble opinion, we’re f*cking heroes!




9 thoughts on “The Composting Toilet

  1. Fascinating and funny read. We are heading off next week to full-time around Europe and we have never spent as much as one night yet in a motorhome, so I’m sure we will have some adventures ahead of us and initially not the ones we expected.

    ! I have talked about these for a year since the previous owner left us the contents of the cassette, which had been brewing for some months. My OH thinks the idea of composting toilets are gross, but she might soon change her mind as she has been nominated cassette emptier 🙂

    I have been watching a guy on eBay who started making them in large plastic storage boxes with a loo seat on top, but he has now refined his design and they are reasonably priced. But I really think that Goldie could benefit from one of these. It would just look like the dog’s whatsits against her exterior. I am guessing that Rodney’s father is not too far from our home if he ever starts his own production run!

    We don’t want stinky chemicals so for now we have opted for a SOG which similarly vent the nasties wafting toward our neighbouring travellers 🙂

    Liked by 1 person

    • Ahhh how I wish I was heading off for the winter. It’s so bloody cold!!May your toilet woes be minimal and insignificant compared to the amazing adventure you have ahead! Though I’d recommend spending a couple of nights in the van closer to home before heading off. Living in a tiny box takes a bit of getting used to! Bon voyage!!!!


  2. You really, truly are composting heroes. I’ve been thinking of doing this for years, there is just no room for a natures head in our camper, even the Separetts are too big. My solution, for what its worth and its not much, was to just use the chemical toilet differently. Place a biodegradeable bag with peat moss in the toilet bowl, and poop into that. Pee goes into the resevior as per normal, except when pooping, try to hold it, or pee into a nalgene bottle. Pee gets dumped on ground or in toilet if available, poop bag goes into airtight fat 50 ammo can (sort of a dry black tank) until can be buried or placed in dumpster. But I like your solution much much better.

    Liked by 1 person

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