KAKAPO© Composting Toilets
Home What, how and why FAQs Operating Installation Troubleshooting
As installed at the Mussel Inn - Onekaka, Golden Bay, NZ.
$4923.37 ex Dunedin, New Zealand
Why composting toilets?
Chances are you are interested in a composting toilet for one of two reasons.
- A conventional waterborne system is inappropriate for your situation due to water constraints and/or drainage problems.
- You have environmental concerns about the impacts of a conventional system and would like to be able to recycle nutrients in an environmentally friendly way.
For whatever reason you may be considering installing a composting toilet, you have already made the most important decision and that is - to deal with the problem yourself.
Having made that decision, all you need to do now is decide on which system best suits your situation and your lifestyle.
There is no composting toilet system that requires as little input from the user as the flush toilet, where you simply push the button and the contents are washed away to some other place for someone else to deal with. All composting toilets require at least some attention from the user at some point - this usually amounts to the addition of suitable bulking or cover material during use and periodic emptying of the collection chamber.
Kakapo composting toilets have been designed to make these tasks as simple as possible and anyone who can turn a handle and occasionally empty a bucket will have no problem operating one.
You will also save at least 30% of your water supply, greatly extend the life of your septic system if you have one and if you are on a municipal sewerage scheme, reduce your loading on their systems by at least 40% (although we cannot guarantee that this will be reflected in a rates reduction unfortunately!)
What is it?
A Kakapo composting toilet consists of a rotating drum inside a semi sealed chamber designed to separate the liquid from the solids and reduce the contents to a more "user friendly" state. It is not intended that full composting will necessarily occur within the toilet itself as this is more efficiently achieved in a separate compost bin where full thermophilic action will ensure a pathogen free, high nutrient end product.
How does it work?
It is a continuous system whereby the input (the seat) is positioned at one end and an outlet at the other. The solid material (faeces, paper and added bulking material) travels along the length of the drum as it is periodically rotated to overflow out of the outlet chute into a receiving container. The container is accessed via a door and is easily removed for emptying from the outside of the building.
The rate of use of the toilet will govern the degree of composting achieved within the toilet itself but it is intended that all out flowing compost will be finished in a separate compost bin.*
Excess liquid drains from the bottom of the drum through a screen, into an evaporation/collection tray. A drain is provided from this tray to a suitable soakage system or collection container **
A vent is provided which produces a partial vacuum within the unit, drawing air in through the toilet seat from the surrounding room. This ensures odour free operation and helps keep the compost aerated.
* Anyone in a rural or suburban situation will have little or no problem finding space for a suitable compost bin. For urban residents, the partially composted material could be placed in a bin to be collected by someone who values this source of high nutrient organic fertilizer or any municipal composting facility should gladly take it.
The liquid can be drained either to an existing septic system or a suitable soakage trench or pit. The average adult produces approximately 1.2 litres of urine a day. Of this, approximately 0.6 litres may pass through the toilet as excess liquid. The dimensions of the soakage system should be designed accordingly. (designs of soakage systems are available) Alternatively, excess liquid can be collected and either placed in the compost bin along with the solid material or applied directly to suitable crops such as citrus or other fruit trees as this is an extremely rich source of nutrient, especially nitrogen.
How is it used?
(see also the operating instructions)
The toilet is used just like any other toilet with two exceptions. After making a solid deposit a handful or two of a high carbon bulking material (such as sawdust or shavings) is sprinkled into the toilet. This material serves the purpose of keeping the compost aerated and friable and also to maintain a favourable carbon to nitrogen ratio required for good composting. Every few days, depending on the rate of use, the drum is rotated three or four times using the crank handle provided (takes about 5 minutes). When the receiving container is full, it is simply removed from the toilet and the contents emptied into the compost bin and covered with straw or other organic matter which will provide adequate cover while maintaining airspaces within the pile. The frequency of this task is directly proportional to the rate of use. In a household of 5 people, with continuous use, this will be approximately once a fortnight. In a bach used once a week you may need to empty only once a year (there is no minimum amount of use required)
After a year has passed, a new compost bin is started. At the end of the second year, the compost in the first bin may safely be applied to any garden - vege or ornamental or to a tree crop (hot composting is the most effective way to kill human pathogens).
For complete information on the composting of human excrement, see The Humanure Handbook by Joseph Jenkins. This is thoroughly recommended reading for anyone considering recycling their personal byproducts, dispelling many myths and putting into everyday language the hows and whys of composting.
Features of the KAKAPO Composting Toilet
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The bulk of the unit is located outside of the building - with only the feed end positioned inside. The advantage of this is that a larger processing drum can be utilised without compromising space within the building. The larger drum size means more thorough mixing of the 'ingredients' can take place within the drum thus producing a more 'user friendly' material for further composting. The removal of processed material is carried out outside the building, eliminating any possible mess factor and odours within the building.
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The unit has a horizontal configuration thus reducing the need for a basement space. Ideal for houses on flat sites. This also makes installation on concrete slab floors and retro fitting to existing buildings possible without major structural changes. (Retro fitting on concrete floors will only require a small step in front of the unit to achieve a normal seat height)
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The vent works on natural convection fan to power.
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The unit is furnished with a crank handle with which the drum is turned - no electricity required.
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No plumbing required other than a simple drain from the unit and a roof flashing where the vent exits.
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The unit comes complete with wall and floor flashing pieces and a standard toilet seat.
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Standard colour is white. The fiberglass housing will readily take a paint finish enabling you to decorate to your particular taste if so desired.
Outside view showing crank handle and hatch containing receiver.
Kakapo composting toilets were designed by Andrew Dixon after much thought and many sleepless nights, specifically for the Mussel Inn, to replace a failing water-borne system. After 12 years of continuous use we are pleased to say they have met all expectations.
They are made in New Zealand and are available for shipping to any destination.
Please contact advfibre39@gmail.com for further information
You will need to supply:
- A suitable drainage pipe away from the toilet.
- A vent pipe - standard 100mm pvc waste pipe is recommended - available from any plumbing or building supply place. Minimum length of 4.5m. This will cost approximately $30.
"In compost we trust"
Operating Instructions Installation Contact the Distributor
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