Given that toilets and sewage are something that most people – including myself for most of my life – never really think too much about, when I express just how much I am thankful for the idea of composting toilets, it probably sounds like a strange exaggeration. Composting toilets are not only environmentally sound, clean and functionally simple but they are also the most natural way (figuratively and metaphorically) to deal with human waste. Ours is particularly simple and that is its beauty, along with being inexpensive. Let’s have a look at what sorts of benefits that this type of system offers over flushing toilets and where they work best, how ours works and where we might make improvements.

Benefits and Uses

First up, let’s look at 10 reasons why composting toilets can be seen as superior to flushing toilets (especially in the right context).

1. Water Conservation:

• Composting toilets do not require water for flushing, contributing to significant water conservation. For example, even with water-saving loos in Australia (3L per half flush, 6L per full) meaning a family of 4 flushes around 28,000 litres of drinking-quality water down the bog every year. In Adelaide, this constitutes 18% (32 GL) of all mains water use from the 200 gigalitres we use every year. It takes energy and resources to purify water, a lot of energy to operate desalination plants and in a state where rainfall is due to decline by as much as 30% by 2050, we can’t afford to minimise the importance of fresh water.

2. Environmental Impact:

• Flushing toilets contribute to water pollution through the release of sewage into water bodies. Composting toilets eliminate this form of pollution, as they do not produce liquid waste that requires treatment. Best of all, “humanure” is natural and, when composted and dealt with appropriately, can be used as a positive way to restore soil health.

3. Significant Reduction in Energy Use:

• Traditional sewage treatment and water supply systems involve significant energy consumption. Composting toilets effectively take away all the energy consumption from the system other than some manual labour in managing your compost.

4. Off-Grid Capability:

• Composting toilets are perfectly suited for off-grid living or in remote areas where access to water and sewage infrastructure is limited. They provide a sanitation solution without the need for extensive plumbing. Once you remove “black water” from your waste system (in most areas, only toilet water is black water now), it is easy to deal with grey water with zero sewage involvement.

5. Nutrient-Rich Compost:

• Not only environmentally friendly from a water or energy perspective, compost produced by composting toilets can be a valuable resource for gardening and agriculture. It is rich in nutrients and can be safely used as fertilizer after proper composting.

6. Odour Control:

• A common concern is that composting toilets smell worse than flushing loos. A properly set up composting one is designed to minimize or eliminate odours through proper ventilation and microbial decomposition. A dry bucket loo will have no odour (other than smells created “in-progress” which is the same as any toilet! 😛 Advanced models often have features like fans and venting systems to keep the compost dry as moisture is usually the only contributor to smell.

7. Reduced Infrastructure Costs:

• Installing traditional sewage systems and water supply infrastructure can be expensive. A composting toilet can be as simple as a bucket under a toilet seat with organic covering material up to a traditional-looking toilet with a chambered unit under the house. Not having a “wet” system means plumbing can be DIY and is very simple to maintain or repair.

8. Resilience to Water Shortages:

• During droughts or water shortages, traditional flushing toilets may face restrictions or challenges. Some eco-minded folks will put a brick in the toilet tank to conserve water or other modifications, but the fact is, toilets need water to work effectively without blocking up. Composting toilets provide a reliable and independent sanitation solution that doesn’t rely on water availability.

9. Reduced Strain on Sewage Systems:

• In areas with overburdened sewage systems, composting toilets can help reduce the strain on infrastructure, preventing issues like sewage overflows and backups. On a localised level, a “blocked toilet” is a thing of the past with a composting toilet, rendering a toilet plunger permanently unneeded! Hooray! It doesn’t matter what you throw down the loo as long as it can naturally break down. In one house we lived in, our old pipes would be routinely infiltrated by tree roots which resulted in horror scenes of raw sewage burbling up through a backyard grate. Yuck-o.

10. Adaptability to Various Climates:

• Composting toilets can function effectively in a range of climates, including cold and remote areas, where traditional sewage systems may be challenging to implement. Frozen pipes aren’t going to affect this system, and hot environments only help get the composting process moving along faster.

Bonus point: Silence. Rather than worrying about plopping or tinkling sounds in a wet loo, nor the sound of a toilet flushing (eg. in the quiet of the night or numerous times with guests over), there is complete silence. Not something to be underestimated in its importance.

Based on many of these reasons, I personally think that we should see a whole lot more people giving composting toilets a try, however the reality is of course much different. Local regulations, and the specific needs of a given community will dictate what is “allowed” or not. Sadly, despite fresh water being a disappearing resource, city councils will probably never adopt any other system other than the one they have as they see human waste as a public health (even though flushing toilets are still reliant on people using and maintaining them properly). However, with more people going off-grid and expanding into semi-rural areas, this is entirely a possible solution.

Our composting toilet experience

We came into the composting toilet idea early on after seeing how effective they were and how many people used them during our Intentional Community trips. There were indoor and outdoor loos-with-views, fancy loos, simple loos. The one thing in common was that they were all inoffensive to use, clean and required no special plumbing. Including our time building our tiny house, we haven’t had a flushing toilet since early 2019. Largely we have not missed it at all:

Pros: the environmental considerations listed above, easy to keep clean, quiet, no unclogging or flooding concerns, no mechanical issues like tank stuck filling.

Cons: requires manually levelling the accumulated pile occasionally for better coverage, can get smelly if people wee in it (see challenges below), no flushing water should things stick to the bowl, every 6 weeks or so the bin needs swapping and old compost needs burying.

Our set-up is based on ones that we saw for sale by companies like Green-Loo who have large multi-chamber polycarbonate units that can fit under tiny houses and will allow the composting activity to occur within. Some units like the Separett include unique urine diverters but you still need to empty compartments plus it requires you to always sit down and I just don’t personally like the way they look. The Green-Loo system is well thought out but much more expensive than we wanted to spend, but we modelled ours off that idea.

The perk to building in a semi-trailer body is the height from the ground. Having just over a meter of clearance means that we could slip a standard wheelie bin underneath which would provide us with a waste receptacle at a fraction of the price of a dedicated system ($75 per bin from Paramount Browns, delivered). We found some handy plans of how to fit-out a bin for this purpose and then just modified it to work with the Green-Loo pedestal toilet, which was our biggest expense ($450). A good-quality fan which sits in-line in the large exhaust pipe out of the bin ran us about $100 too.

The design is based around the idea that there is a sub-compartment separated by a mesh barrier that allows liquids to accumulate in the lower reservoir and then a hose from that lower area allows fluids to leak into a run-off pit as needed. The mesh barrier keeps the solids compost up top and then near the very top of the bin is a hole for the vent pipe and fan. The wheelie bin has its attached lid hanging off the back, unused until it gets swapped for a fresh bin, then closed up and sat in the sun to ferment. A standalone lid with a hole cut in the middle hugs the main toilet shaft from the house above and sits snug over the bin to keep it sealed up. In the house, the toilet pedestal looks like any other toilet and the only giveaway is no tank or flusher. To further conceal the nature of the system, we have a couple of storage boxes built into the wall as drawers which hold the bulking material that you use to cover your business in the toilet after you’ve gone. Added innovation: the bulking material boxes are in a two-way hole that leads out to the back of the trailer where two large bulk storage bins reside in the wall of the trailer. They can each hold about 200 litres of material so it allows us to easily top up the internal bins without having to drag anything in through the house.

Watch the video at the bottom of this page of how I put it all together and what the system looks like.

The result: a largely fuss-free toilet experience but not without both some caveats and planned changes. Initially, we used the toilet for all activities with the intent to allow liquids to drain out, keeping things dry enough not to smell with the fan doing its job to dry out what was there and draw away remaining smells. In the winter and when the bin is less than half full, this worked well enough. If we didn’t use enough covering material (or the right covering material…it took us time to get that right) then it might smell for a short time after a wee until it got soaked up into the pile (we tend to use bulk garden compost mixed with soil from our yard for solids and pet bedding sawdust for liquids). With two of us working from home, it was just too much fluid in the system so I just went outside for my contribution (which wasn’t terrible: there is no one around where we are and it gets me outside). Come summer, the toilet smelled a bit more which led to Heidi avoiding weeing into the toilet at all and using a bucket and then dumping outside. Obviously this is not rendering our toilet system too useful if we are only using it each once a day!

With the decision to keep our other semi-trailer (P2) and fit it out as a guest space, we decided it made sense to add a toilet there too. On a couple of our intentional community visits we came across duel toilet set-ups and thought this made sense in P2. This way we can make the toilet in our main house (P1) a dedicated wee-only toilet which will allow it to be used many times a day, with a dedicated wee-only toilet right next to a dedicated poo-only toilet in P2. The only downsides to this idea are that it means someone must use the poo-only (which is really just like the one in P1 now, so it can take fluids too if someone is unsure of what might come out 😱) for poo, and never never do a number 2 in the wee toilet which will be fitted with essentially a funnel connected to a hose! Also, my handy-dandy bulking material bins will be rendered useless in P1 (although, I’ll set it up so that the original set-up can be easily implemented if that suits us in some future scenario).

Overall, we really like the composting toilet set-up. We have a special microbacterial spray that speeds up the process of composting in the toilet and doubles as a cleaner so keeping the bowl clean is easy. It looks good, there is no splashing or flushing or brushing required. There is no plumbing, septic, sewage costs and most importantly, water wastage. It does require a slightly more hands-on approach to swap out bins and bury compost, plus manage bulking/covering material.

If you want to visually check out the process and the result, have a watch of the video below. Let me know if you have any questions or comments in the section below!