5 Tips for Composting Toilets

According to the U.S. Environmental Protection Agency, the average American family of four uses 400 gallons of water in the home and garden per day. Of that, as much as 27 percent can be down to toilet use alone. When you consider that the standard modern toilet uses an approximately 1.6 gallons of water for each flush (with older models sometimes using as much as 7 gallons) it’s easy to see how it adds up.

Because water is not (as many people think) an infinite resource, such levels of use are going to be unsustainable in the long-term. Permaculture emphasizes the preservation and efficient use of water on the land (through mulching, planting native species, contouring, and so on) and in the home (taking showers rather than baths, reusing bathwater for irrigation, and similar techniques).

One significant step towards conserving water is the use of a composting toilet. For some people, the thought of a composting toilet is a step too far, imagining that they are smelly or unhygienic in some way. But, in fact, composting toilets are very sanitary and do not smell if treated correctly. They are water-less or use a very small amount of water compared to conventional lavatories (and those models that do have some need for water can easily be serviced by rainwater harvesting).

The other benefit of a composting toilet is, as the name suggests, they provide material for composting. Such a sanitation device serves to create a ‘closed loop’ system, which fits in with the principles of permaculture by being a self-sufficient system, not requiring any outside inputs. Consider that we eat plants for food, that food produces waste, then, with a composting toilet, the waste goes towards growing more plants. These sorts of closed system are found so often in nature, so it makes sense to replicate them on our permaculture plots wherever possible.

Pre-fabricated composting toilets are becoming increasingly available on the market, but the permaculture gardener could also consider constructing their own version. Here are some tips for composting toilets.

The best set-up for a composting toilet is to have two tanks: one for liquid and one for solids (you could have a pump that diverts one from the other, but having separate tanks is the easiest method). This is because urine can be used on the garden immediately, while feces must be composted.

When expelled, urine is sterile and full of nutrients. It contains most of the potassium, phosphorous and nitrogen that our bodies get rid. And in a marvelous piece of symmetry, those are three of the most important elements for plant growth. The reason to split your composting toilet is that urine can be contaminated if it comes into contact with feces; if kept separated, it can be used straight away on the garden, with no need for composting. Dilute one part urine to six parts water (rainwater, where possible) and add to garden beds. You need a tight-fitting lid over the urine receptacle in the toilet, as contact with oxygen in the air can turn the nitrogen in the liquid into ammonia, which will not only burn you plants, it will make the toilet smell.

Feces, on the other hand, must be composted before it can be used on garden beds. When it is initially expelled, it tips for composting toiletscan contain microorganisms and bacteria that are harmful to human health, and if put straight onto the garden, these organisms can be taken up by the plant and so the crop that the gardener will eat. Ideally human waste should have its own composting pile, as it takes longer to break down to a safe form than other waste, such as scraps from the kitchen, and should be left without human contact until fully composted, to avoid the risk of contamination by pathogens before they are broken down. However, if you don’t have a need for compost in the immediate future, you can compost all your waste together; just maintain good hygiene standards when adding kitchen waste to the pile. The feces needs a bulking agent that contains air gaps that allow the functioning of aerobic bacteria to break down the waste. Sawdust and straw are good choices, but rice hulls, peat moss and leaf litter can also be used. The toilet paper and the cardboard tubes at the center of the rolls are perfectly fine to add to the compost pile, just try to use organic, sustainable products. As it should be left in isolation, you won’t be turning the pile as you would a conventional one, so do not cover the pile with a plastic sheet, as it needs air to function. Covering the waste with the bulking agent will prevent odors. The compost pile should also be set up on a soil base so organisms for the soil can enter from the bottom. To fully compost human waste takes about six months.

A composting toilet needs ventilation to add oxygen and prevent the build up of odors. Some composting toilets simply have one side open, facing away from other buildings, but you could consider a three quarter-length door with spaces below and beneath, as well as a vent in the roof. If the toilet does begin to smell, keep a box of a bulking agent, such as sawdust, at hand and add to the tank after depositing. This damps down any odors.

On thing that can put people off installing a composting toilet is that it will require endless emptying, but in fact it can be surprising how little actually accumulates. On average a 25-liter container will take 2 adults around 10 weeks to fill. When you empty a container you will need to wash it thoroughly before reuse, to ensure no pathogens are left behind. Use a long-handled brush and rainwater. It’s really no worse than cleaning the kitchen bin, and you can be secure in the knowledge that you are saving water, preventing pollution and creating valuable compost.


I want a composting toilet. The old regular one I use now I flush with water from a plastic pitcher filled in the tub. Can’t find composting one that is small and affordable, yet.

Ummmmm I still need to be swayed

I’ll persuade you someday.

Okay we will see sooner than later I’m sure ..lol

I’m ok with my toilet since I don’t flush after every pee. But I’d like a legal grey-water reuse system. Either for in-house use (to flush toilet) snd/or outdoor.

this is why i think a well and septic tank is the way to go…….city water/sewers are pumped to and from miles away….a septic tank basicly recycles water right there on your own land

where does the water go after it leaves to toilet?

Jarod would this be similar to a bokashi bucket (they compost fruit and veg scraps) re: By using enzymes I think …

A composting toilet is in my future. Thanks for the info.

Tread carefully before going this route! There are many claims and promises from many companies to deal with. We have used one for over 5 years now. Our next one will have the main unit in the basement,and, have a low flow flush. All of these are “hands on” and not just “Flush & Forget”! Many may find that coming this close to Nature is hard to do.

having spent a good deal of time around composting toilets I have noticed one thing…there is a reason we have use a lot of water to flush it away. Nice theory, poor in practice.


“The compost pile should also be set up on a soil base so organisms for the soil can enter from the bottom.”

This piece of information is incorrect and potentially dangerous. Per The Humanure Handbook by Joe Jenkins, a man from Western PA who has been successfully composting human waste for over 25 years, you do NOT want to have your humanure compost pile in direct contact with the soil, as some of the pathogens that can be present in the feces will persist in the soil. Instead, Jenkins recommends making a simple “biomat” of hay, straw, etc. that is several inches thick and prevents feces from directly contacting the soil, but encourages microbial activity to break it down.

For those interested, you can view Jenkins’ book online for free through his website: http://humanurehandbook.com/. I highly recommend it before embarking on the humanure path, as it is quite comprehensive from both a scientific and process standpoint.


We ha e a C-Head on our liveaboard sail boat. Love it easy to use and deal with. Would never go back.


I designed and built a composting toilet with urine diverter. We used it for 23 years. There was no odor. We only had to empty it once a year because I added “red wiggler” worms to it.


Real composting NEED volume … composting in a bucket fails because there is not enough mass to give it the needed stability, so it hits the border conditions too easily … they either get to wet [and over-flows onto the floor] or they get too dry and you have to remove a hard brick.
Traditionally the maker of various alternative toilets have overemphasized the ecology and not paid enough attention to the user need … so now the next generation has tried to change that … see http://youtu.be/39GL1Fj6GHs


I, Alan Kreglow have been happily without running water All of 2015. It started by accident and is now my preference.

Regarding alternatives to flushing the toilet my choice has been to line a bowl or box with many layers of newspaper and stand and deliver feces into the newspaper, together with used toilet paper.

Then I roll it all up like a Tootsie Roll and store these rolls in plastic garbage bags in my wood stove until I’m ready to burn them.

Washing dishes is done with hot water in glass sprayer bottle, using Miracle II soap only when necessary. My dishes are Clean using Very little water.

I wash my skin exclusively with hot r/o water. Makes the skin very healthy and feels as refreshing as a shower.

An occasional coffee enema, flushed in the usual way (using an amazingly large amount of water – 7-8 gallons for everything) keeps my body happy and healthy.

Regardless of alternative toilet etc., I HIGHLY recommend coffee enemas once a week or so. They are even More valuable than fasting on liquids one day a week.

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