Waste Management: Getting down and (not) dirty with dry toilets, composting toilets, dehydrating toilets, humanure, soak aways – closing the loop on bio-waste.
(Full disclosure, I’ve been waiting all week to write my punny title for this post. I know, I know…)
Compost Toilets: Myth Busting
- Compost toilets, used correctly, do not stink or have flies.
- They are actually very easy and affordable to set up.
- The waste can be composted safely by following a few simple guidelines.
- They are safe, sanitary and clean.
- They can be used indoors, in your bathroom, just like a water toilet.
- Like a water system, you can put toilet paper, biodegradable/cotton tampons etc in your toilet – but not disposable nappies, pads or anything containing plastic / non-biodegradable items.
Benefits of a Compost Toilet
Choosing a compost toilet over a water toilet is, in my mind, one of the best and easiest choices you can make if you want to go green. Waste shouldn’t be put in water – it should go back to the earth, as per the natural cycle. Instead of flushing it away, you could be feeding your soil with well-composted manure, enriching it and replenishing it. People can be a little skittish about composting toilets, but really, there’s no mystery – and you can choose a set up to custom suit your needs! In this post, I’ll chat about the system I’ve chosen to go with, and how I arrived there.
The Basic Box
A compost toilet can be as simple as a toilet lid over a bucket. The two main criteria are that the lid be firmly attached to the container (no gaps) so as to block out flies and other critters, and that you have a suitable organic matter to cover your waste after each use.
The most common and effective covering used is sawdust, but I’ve heard of people using dried grass cuttings (not as effective as sawdust in airflow allowance), dried leaves (not always available) and sand (beware the weight accumulation), among other things. One or two scoops of sawdust is usually sufficient – all you need to do is make sure the waste is covered. Its ok if a bit of toilet paper peeks through.
Once the bucket is full, remove the toilet lid and replace it with a lid punctured with some air holes to allow for evaporation, keeping the holes small enough to prevent critters from sneaking in. Set it aside out of direct sunlight and sheltered from the rain to continue composting, and put a second bucket under the toilet seat.
By the time the second bucket is full, the first bucket should have had some months to decompose and be safe to add to your usual compost pile. Empty bucket one, set bucket two aside, and so the cycle continues. If you find your bucket gets filled up before bucket two is ready to add to the compost heap, simply add an extra bucket to your rotation to allow the full bucket/s more time to decompose. We’ll be using the bucket method – albeit in a luxuriously designed Sylvantutch throne – until we build our permanent home (the first few months on our land are going to be camping).
Going one step further from the basic box compost toilet, you can add a urine splitter. It’s basically a funnel that fits over the front half of your toilet, channelling the liquid one way while the solids drop straight down.
Splitting the urine from the solid waste has some great advantages. Firstly, since human waste is 90% water, by separating your urine output from your solid waste output, it takes a lot longer to fill up your bucket. Its worth noting that urine, being high in nitrogen, does speed up the composting process – its a great compost activator. But its easy to circumvent that loss by adding urine to your compost heap or resting bucket if you want to give it a boost, either by the occasional collection or the ‘el-naturale’ method (the ever portable man snake is a winner here).
Separating the urine from the solid waste also reduces smell dramatically. Less moisture = less odour overall. The above picture shows the Sylvantutch toilet using the bottle collection method. The front of the toilet box has a hatch you can open to easily access the bottle.
Another great benefit of separating the ones from the twos is that you get to use your urine in the garden. Urine is fantastic for your plants! Its full of nitrogen, potassium and phosphorus, which are the nutrients plants need to thrive—and the main ingredients in common mineral fertilizers. Coming straight out of the human body, urine is actually sterile and safe to add to soil. Just make sure you don’t overdo it in a single area – think about how too much fertilizer can burn your plants if spread too thick or not diluted enough.
You can buy specially made urine splitters to fit to your compost toilet, or buy ready made compost toilets that come with one. Some people use separate toilets (one for urine and one for solids) but I don’t think that’s a very practical approach. You could probably also make your own splitter with a bit of trial and error, but it’s not something I’ve explored myself.
The urine, once separated, can be funnelled into a container which would need to be emptied daily to avoid a smell. We’ll be going with the bottle method to begin with during phase one of our moving onto the land plan.
Once we’ve lived on the land for a while and have locked in our building plans (and just gotten a better feel for the land), we’ll upgrade to a permanent soak away. A soak away means using a pipe from the urine splitter to carry the urine away from the toilet. The pipe can then be buried underground in the garden in a spot of your choosing – nitrogen loving plants grown over this area will thrive. The benefit of doing this is that once in, you don’t need to empty the bottle collector every day.
I still need to do more research into this step, but initial study suggests burying the pipe around 10cm into the ground and perforating it along its length (even adding several branched out pipes), so that the urine is spread out over a larger area for plants to use without being overwhelmed. By keeping the flow towards the top of the soil and spreading it out over a large area, the risk of groundwater contamination can be offset. Since our plot is next to a river, we’ll need to do a LOT of research and fact-checking before we go ahead.
Adding a ventilation pipe / chimney to the set up naturally increases evaporation and removal of odours. An extractor fan can further assist in drawing the warm, moisture laden air out. The result is that the solid waste loses a lot of mass, reducing in size.
Ecosan has a dry toilet available here in South Africa that involves a somewhat complicated corkscrew device to shift solid waste along a tube before dropping it, ‘dry and odourless’, into a collection bag, thanks to the combination of the slow corkscrew progress and the ventilation pipe.
I’ve pulled information and bits of designs from many sources, but John Seymour’s “The New Complete Book of Self Sufficiency – The Classic Guide for Realists and Dreamers” was the first compost toilet I came across to improve on the simple long-drop, or pit latrine. His book has been a massive inspiration to me on all fronts, and has been one of the most referred-back-to books on my bookshelf for years.
Here is a breakdown of what I plan to do when we build our home:
1. Keeping the compost toilet with urine splitter, urine being diverted via a pipe to a garden area outside the house.
2. Solid waste falling down into a large container on wheels. This container is housed inside a brick/cement chamber underneath the toilet, below the bathroom floor. The chamber is built with a slight downward angle.
3. Outside the bathroom on the exterior wall, a ventilation pipe/chimney flue connects to the chamber, running up the side of the house to the roof. A fly screen prevents unwanted guests making their way down the flue into the chamber.
4. An extractor fan fitted to the ventilation pipe inside the chamber increases the flow of air upwards.
5. A hatch allows access to the chamber from outside the house, where the container can be wheeled out when full, and depending on the level of decomposition, either a second container rolled in while the first container is fitted with a lid to decompose further, or if its ready to go, emptied into the compost pile and returned.
Envirosan’s design was my main inspiration – the only things I’ve added are a slight slant to the floor, a fly screen and an extractor fan. Here’s their much more legible design:
Our toilet from Sylvantutch should be arriving next week – just in time for our next trip to Suurbraak for our first camp-stay on the land. I’m probably more excited than I should be about a toilet, but what can I say – compost toilets make me happy!