How to Safely Compost Human Waste


How to Compost Human Waste

Fully Composted Human Waste

Composted Human Waste is excellent fertilizer for non-edible plants.

This is an article on how to safely and easily compost human waste. It’s not difficult, but you MUST do it right, or people could get sick. The main issue is the solid waste – feces. It’s easy to deal with urine. More on urine below.

Solid human waste (feces) can be safely composted by carefully following a few simple guidelines. These are my suggestions only, based on the comprehensive Composting Toilet Guidelines published by the Government of British Columbia in Canada, and recommendations from the World Health Organization. I make no guarantees about the accuracy of this information, and if in doubt you should check with your local authorities.

First, it is much easier to compost human waste waste from a urine diverting composting toilet. The material removed from a urine diverting toilet should be just slightly damp – perfect for composting. With a non-urine diverting toilet, the contents will be too wet for efficient composting, and the combination of urine and feces creates an anaerobic environment that allows very stinky bacteria to flourish (think outhouse or portable toilet at large public event. Ugh!). A urine diverting toilet is key to the successful composting of human waste, in my opinion.

compost human waste

Composted Human Waste

When the human waste is removed from the toilet, you should place it in a dedicated composter. The type of container is very, very important! It must not leach out the bottom or sides, as this might contaminate groundwater. It must be protected from rain and snow – it cannot get wet. And it must have lots of ventilation. The easiest way to meet these requirements is a rotating compost drum or barrel that sits off the ground. You can build one if you are handy, and there are many sites on the web showing how to do that. You can also buy one fairly inexpensively. In my area hardware stores carry them starting at around $100.

composting human waste tumbler

Two compost tumblers would be ideal for composting human waste

You can add leaves or grass to the compost bin. However, I don’t like to add too much vegetable waste as it seems to make the contents too damp. It is a good idea to learn a bit about composting basics. You should monitor the contents from time to time. If it seems wet (it should be just slightly damp), add dry grass, dry leaves, or some other dry carbon rich material. If it’s too dry, you’ll need to add a bit of water, and possibly more nitrogen rich material like green plants. It’s actually pretty simple and easy. Keeping the contents just slightly damp will ensure rapid and complete composting.

Additional Tips to Successfully Compost Human Waste

You need two compost bins to compost human waste. Use one at a time. When the first bin is full, start using the second bin. When the second bin is full, the first one should be ready for the plants.

Add lime to the compost bin. This will drastically reduce the time it has to sit, before being safe to bury or spread on non-edible plants. Use roughly 3% lime to total waste volume – i.e. if you have a full 50 gallon drum of waste, use 1.5 gallons of lime. These numbers are very approximate. With lime added, the bin needs to sit undisturbed, without adding new material, for 120 days. This should kill all pathogens. Without the lime, the time frame is much more uncertain, and varies from 6 month to 2 years, according to various sources.

You must never put composted human waste on edible plants, because of the small chance that dangerous bacteria is still alive in the waste. Always use human waste compost on non-edible plants only, or bury it.

Pee is Easy!

It is extremely easy to deal with urine from a urine diverting toilet. You can just use it as fertilizer! Some people dilute it, others do not find dilution necessary.

You can download a wonderful guide to using urine as fertilizer from the Rich Earth Institute here. They have worked with numerous universities, public health regulators, the WHO and even the EPA to establish principles for using urine from a urine diverting toilet as fertilizer. The take away message from this guide is that, at the household level, urine is not a health risk, and can be used directly on plants without treatment. Sadly, many (most?) local governments are unaware of the facts around urine, and think it is somehow dangerous. Not true. Send them the guidelines.

If you follow these simple steps, you will have a complete, safe, odor free and low cost waste treatment facility on your property. Unlike conventional sewage or septic systems, you will completing the circle of nutrients, returning much of what you consumed back to the earth. You won’t be creating toxic sludge to be burned in a high temperature furnace, or treated in a typical sewage treatment plant using vast amounts of energy and producing considerable CO2.

 


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20 thoughts on “How to Safely Compost Human Waste

  • Johannes

    Your well measured input on the proper, safe use of human manure is highly appreciated. I am a 51 year old South African who grew up surrounded by multitudes of subsistence vegetable farmers who never thought twice about the value of using human manure in growing their edible cash crops and we never heard about any resultant health risk of such usage. What has really changed from my daily witnessed life experience of human waste usage? My somewhat stronger personal feelings are, once human manure is adequately treated, it should be safer to be used on edible crops as well.

    • richardbrunt Post author

      Human waste has the potential to be extremely dangerous. “Adequate treatment” is tricky to achieve. A small amount of E coli can cause severe illness, blindness or death. Careful studies have shown that very small amounts E coli (and other pathogens) may occasionally be present in human waste even after 1 year of composting. You can’t know if your compost is safe, without sophisticated testing. It’s not worth the risk. The WHO and other health organizations state that we should therefore not use human waste on food crops. In Haiti, human waste is very carefully composted in a large scale commercial facility, and the temperature reaches 55 degrees C for a week or more. This kills everything. Then the waste is tested repeatedly, and only after it is determined to be pathogen free, it is used on crops. So yes, it’s possible. But generally it’s not practical. I strongly recommend never using human waste on edible crops.

      • Henriette Vermaak

        Hi Richard
        Have you been involved in the making and testing of humanure?
        Can you support your strong opinion about the dangers of human waste in a composting process with relevant research – that contradicts the research done by SOIL in Haiti and x-runner in Peru?
        Please let me know – as we can provide information to the contrary.
        Regards

        • richardbrunt Post author

          In Haiti it works because highly qualified, well trained people are monitoring the pathogen content of the waste with sophisticated lab testing. They know that the temperature of each compost pile has to reach a sustained, very high temperature, and they closely monitor the temperature of all areas of the pile. This is relatively easy to reach in a tropical climate, and hard to reach in most part of North America. Most people do not have the knowledge, training, skill or expertise to do this safely. So it’s not safe to do. This is why the World Health Organization recommends using compost made from human waste on non edible plants. The humanure approach relies on a very long waiting period, to ensure there are no dangerous pathogens. But small amounts of E Coli have been found in human waste stored for long periods, even a year or longer. Recently a child in California went permanently blind from eating food contaminated with E Coli. That’s a human being that will live their life in darkness because of someone’s relaxed attitude around human (and animal) waste. Putting human waste on edible plants, unless you have the equipment, training, lab facilities, skill and motivation to do it properly, is a bad idea.

  • Jan Fekkes

    Richard, I purchased a Villa toilet from you about 5 years ago. In the composting discussion and questions, there is nothing about the green bags and how long they take to decompose. I have been putting the bags in my regular compost and they are still visible a year later. I’m wondering about the incinerator advertised on the Separett website, or if there are any other incinerator products you might recommend.

    Jan

    • richardbrunt Post author

      Incinerators are a bad idea. They use an enormous amount of power, and have incredibly expensive parts that fail regularly. They are the absolute worst solution in my view.

      If the bags have not composted, then you are not composting successfully. They break down quite easily. Usually too easily. I suspect your compost is too dry. Please see my page on how to compost human waste, and possibly read more on numerous websites about composting in general.

      Also, small fragments of bags are not a problem. Remember never to use compost made from human waste on edible plants.

  • Dakota

    What is the difference between composting human and animal waste? Are there any other materials needed to compost human waste? Can Urine Diverting Toilets be keep in a home?

    Thank you!

  • Jennifer Campbell

    I’ve been interested in humanure since I’ve learned about it from YouTube years ago. However, they used it for fruits and vegetables as well. There has to be a way to confirm if the pathogens have died so I can use it for fruits and vegetables plants. I don’t want to bury perfectly good usable compost if I don’t have to. I would like as much information as possible because I would like to develop it for larger scale planting…
    Thanks in advance!
    Jennifer

    • richardbrunt Post author

      The compost can be taken to a lab, but it is expensive and hence impractical. It is done in Haiti and Africa but under strictly controlled and monitored conditions where the compost has to reach and maintain very high temperatures. Don’t under estimate the danger here. E coli can kill people. Use it on ornamental plants only after a lengthy period of composting and it is safe. Using humanure on vegetables is gambling with people’s lives, and against all WHO guidelines.

  • deb tolman

    Where can I find out more about the compost tumbler shown on this page…can’t seem to find it anywhere online.
    thank you.
    d

  • Isaac

    What happens if there is urine mixed with the human waste., how do you separate the urine from the feces before composting..

    Secondly., how is the safest way to apply human waste compost to crop fields such as corn and pepper farms..?

    • richardbrunt Post author

      The urine is separated in the bowl, by the toilet. If urine and solid waste is combined, it will smell much worse. You cannot apply human waste compost to food crops, because of the small risk that the material you are using is not fully composted. Use on non-edible plants only.