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A moldering toilet is simply a waterless toilet that is built to allow for very long term slow decomposition in place – the waste molders, rather than composts, much as leaves and plant debris "molder" on the surface of soil through the action of bacteria, fungi, and microorganisms. With moldering, the "technology" applied for waste treatment is mainly isolation, and simply time itself!  All that is required is a temperature and humidity stable aerated vault that can support enhanced growth of fungus.  There is no heat generated and consequently no nutrient is 'burned' out of the pile - all of the nitrogen in the waste AND that generated by decomposing microbes is sequestered in the finished product.  Virtually no carbon is consumed because there is no high temperatures to create carbon based 'greenhouse gases'.  After a year or more, all you are left with is half the mass of the original waste converted into fine, lite weight black humus suitable for application back into your landscape and virtually all of the moisture (80% of the original weight!) evaporated into the atmosphere.  

On the other hand, a "composting" process is typically associated with fairly fast transformations, in the neighborhood of weeks and months and is normally associated with elevated temperatures induced by the rapid consumption of nutrients in the waste. It necessarily requires quite specific man-made conditions and technologies to do it’s magic in such short time periods. Usually, this requires an environment that encourages elevated temperatures, enhanced oxygen and air mixing (fans), critical moisture control (heaters) and specific control of the waste material makeup and loading rate (special starters and additives).  These toilets often need to include stuff like electric heaters and mechanical stirrers and sophisticated baffle arrangements to accomplish this reliably. They sometimes incorporate a portable collection device for raw waste, for the waste may have to be transferred to another location for composting. These are often small, compact, store-bought off-the-shelf  units suitable for a quick solution when waterless is the only way to go.  Unfortunately, Health Code standards by normal definition never permit building your own composting toilet.   They are not considered as safe until the National Sanitary Foundation has approved a design as suitable for manufacturing and general public availability.   

The SunnyJohn was designed to meet the 'vault privy' standards of the Colorado Health Department's Guidelines for 'Individual Sewage Disposal Systems'.  It is essentially a pumpable, water proof concrete vault completely sealed from the water table, vermin and flys.  It's safe in the environment for long term heirloom constructions and you can build one yourself.  If your project meets the detailing and design criteria of a 'vault privy' in your local code district, and your local officials allow 'vault privy's' you can have it approved for use as your own waste management solution. 

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Composting and moldering toilets use no water. On the other hand, the flush toilet is pretty much the be all and end all of human living in much of the modern world. The major objection to all variations of water-based waste disposal is the expense of infrastructure. Rural septic leach field systems cost anywhere from $6,000 to $20,000, while municipal sewer connections are no less costly and require continual energy inputs to maintain. Basically both take drinking quality water, dump sewage into it, use the water to transport the waste, and then attempt to remove that sewage from the water somewhere else. Most water-based systems give little consideration to completing a cycle where it begins – on the farm or in the garden.  Instead they turn a local critically useful resource into a regional waste nightmare. Worst of all, water-based systems are usually installed simply because of the lack of knowledge of legal, workable alternatives.

When you see that required maintenance could be as low as once every few years,  advantages to using a long-term moldering design immediately present themselves. Besides the work and investment saved, moldering systems lend themselves to maintaining an atmosphere around the home of simplicity and repose. Traditional portable-sized composting toilets need more frequent maintenance; their processing is much quicker and so their products need more frequent handling and careful control over the rate of loading. A moldering toilet may only need attention every four to five years if you like. And wildly fluctuating load rates are not a problem... the SunnyJohn inherently by design can easily accommodate short haul load increases of 500% or more.  As the size of the moldering container or vault increases, the time span can be permanently expanded with the simple addition of more $10 containers.  And still yield treated products to properly cycle back into your natural system.

Portable composters are efficient waste processors, so their overall size is fairly small. They can handle their load quickly, and so do not need to have large amounts of internal storage. They are designed to treat quickly, and then need unloading. Herein lies the weakest point in their design. If the loading characteristics of a composting toilet ever change significantly beyond the design limits, it will stop doing its job of transformation. It will just fill up and need to be abandoned or cleaned of raw waste! (That workshop you dreamed of hosting at your site — with 35 people showing up for 14 days — will mean only one thing! a mess or worse, renting portaboties!) On the other hand, a design which incorporates large storage times will also be able to handle loading fluctuations without breaking down. The moldering approach to design leaves you with more time to play with and is more resilient to load fluctuations.

The main reason for composting wastes is, of course, is to make nutrient available to the soil - for which we are permanently indebted - returning all the products of your labor and partaking to the Earth. Completing this one simple mineral re-cycle quietly and with little effort stands out as the major advantage. Whatever the method, an important ritual for any and all can be letting the products of our bodies be returned to the Earth better than from whence they came.

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The obvious reason not to choose any on-site dry waste treatment system is that sooner or later you will have to handle human waste directly. This will be the point of departure for many; the thought of it will send the squeamish running. That is just the way things are, and will always be the objection to any kind of direct hands-on home management of human waste. However, do not fear, when properly functioning, the moldering toilet produces finished material which looks and smells just like and for all intents and purposes is forest duff.

The second disadvantage is the size of the chamber required. Portable composting toilets and water-based systems don’t need a lot of building space, whereas a moldering toilet must incorporate a large chamber in order to store up several years’ wastes. And this chamber must be beneath the toilet room, sheltered from severe cold, well ventilated, protected from vermin and meet Individual Sewage Disposal guidelines.

As well, with any new approach being prototyped and perfected, the lack of experience and skilled execution of designs may be a problem. While the general approach to this type of waste treatment may be well understood, a lack of the hands-on knowledge of the finer details of accepted and understood construction practices may put the whole process in jeopardy. 

(Note: The included report in the SunnyJohn Plans package is intended to provide practical introductory guidance only. Perfect execution of good design always requires the application of the designer/builder's inspired imagination through the skill set of qualified construction tradesmen.)  

The other possible hindrance is the legality (or lack of it) that may surround this approach. I don’t know of any law that makes it illegal to do your thing in a bucket (essentially, that is what all composting toilets amount to), but what you do with the bucket when it needs emptying may be an issue! Seriously though, let's let common sense and the applicable codes determine the right and fitting thing to do. Composting toilets are accepted in many areas of the country now. Look for precedence in your area, and go from there.  As the fresh water crisis looms, many officials are actually encouraging homeowners to consider waterless solutions.  The Sunny John is just one of many that meet the guidelines in place.

The original impulse for the first design I considered sprung out of a need for a restroom at a working farm site that hadn’t a waste water system available to expand. It needed a second facility for farm hands and many visitors to relieve the strain on the existing septic system (not to mention the strain on the carpet and privacy of the farm manager’s household!) A simple pit outhouse was out of the question — a nearby well would be threatened. As well, the whole idea of on-site recycling was mandated; it was being actively pursued in most areas already. As well, the opportunity to house the toilet in a structure built to Eco-friendly building standards came about by lucky providence — a project was needed to demonstrate timber frame and straw-clay wall construction methods. The vision slowly grew into a full expression of simple beauty and natural function. The reason why we built the moldering toilet as we did came to relate more to this expression of a vision than simply an effort to satisfy a need. It eventually became a symbol for all to see, and for all to know.  You must "Do, show, and then know..." to be ahead of the pack.

Why would anyone want a moldering toilet? The answer to this question relates to the advantages of having one. Namely — on-site human waste recycling, infrequent maintenance and no water-based sewage infrastructure requirements and expense.

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Many designs have been implemented using one vault for the waste, but most have seen the need for two vaults.  Implicit in the moldering process is a long resting period: the full waste vault must be left undisturbed for a minimum of six months, while fungi, bacteria and microorganisms break down the waste without any addition of fresh material. This requires that you build a second vault to be used while the first is resting. The vaults can be sized to hold more than six months’ loading, allowing for a longer resting period, up to several years. As the first one is filled, it is capped off, and use is directed to the other. Once the second vault is nearing capacity, the first vault’s contents can be harvested as finished compost, ready for orchard and field. The second vault can then be inoculated with worms, capped off aerobically, and the first brought back into service.

My first design used removable 55-gallon containers in each vault to allow for more flexible loading rates and easier handling of the finished product. Two of these barrels provide a year’s capacity for a family of four. To date this has been proven to be the best solution.  The barrels are cheap (often free, but typically available as low as $10 reconditioned), very manageable and allow you to have more than the two in the vault... you can have many on hand to handle larger loads if required.

During the summer, the design relies on wind power for ventilation, and ambient air temperature for heating. During the winter, when the sun is lower in the sky, solar energy is used to boost venting and to heat both the space and the vault. Wind continues to be used for ventilation.  A thermostatic damper controls the amount of winter venting to prevent deep cooling.  Tons of additional mass is incorporated into the second vault to thermally drive the chimney venting even when wind and solar influences are absolutely nil.  

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If the waste is to be collected for long periods, there must be enough elevation from the floor of the vault to the level of the toilet stool to allow 55 gallon barrel to clear. Four feet or more is not unusual. The overall size of the vaults will be determined by the projected loading requirements and the space available.

Access to the vault will have to be provided for harvesting. A wheelbarrow, cart or vehicle will likely be required, as the volumes involved will be large. This means a large door which seals well, and a location adjacent to a flat, unencumbered space for unloading and transferring the material.

The vault must be very well ventilated too. Ventilation provides the oxygen required to maintain aerobic fungal and bacterial activity sufficiently to reduce odors. Many, many times higher than normal ventilation will also evaporate excess urine and help to keep the toilet room fresh. A vent stack which draws air through the toilet seat or bench, around and under the pile before exhausting it above the roof line will serve these purposes well. If free energies such as sun and wind can be harnessed for this purpose, operating costs will be low and reliability built in. Of course, if passive powering does not cover all possible eventualities, the design will be forced to rely on mechanical ventilation.

The waste must not be allowed to get too cold for significant periods of time. This means the vaults will need to maintain temperatures above normal ground and winter ambient temperatures. Temperatures approaching 90^oF are not too high, while and annual average low of 70^oF would be a good design target, with annual lows of 60^oF still manageable. 

The last matter to consider is that the building must be built soundly and tightly. All entrances and accesses must be made vermin and fly-proof. Door seals and gaskets must be used,  the traditional toilet seat must be sealed with gaskets or substituted with special air tight seats and the vault and it's access doors must be weather-stripped as well. The vent piping, must be screened as with all openings to the outside. Flies can be a major concern, as they can readily infest the vault and room.  And they do, spiders can cast an impenetrable web in the venting system if there is a payload of insects to harvest. If the venting is compromised, odors and poor evaporation of liquids will be the consequence. Pay careful attention to the integrity of the structure! We've also since discovered that we get good breakdown of the waste ONLY if we introduce redworms in each barrel after they are full.  See more info and Plan Updates

Summarized, the following criterion need to be met:

1. space,
2. ventilation (for odors and moisture evaporation)
3. warmth (for breakdown, comfort and evaporation,)
4. integrity and screening (to prevent unwanted vermin and pests)
5. harvesting access.

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When I built this first prototype moldering toilet it had to be placed in the central working area of the farm. There was no opportunity to add onto the farmhouse. We had no elevations to use to our advantage. The design had to be built around a modified pit setup. The space also did not allow direct solar exposure of the vault for heating.

I built a timberframe, light clay structure, almost totally free of modern materials. Straw-clay walls lent themselves well to the needs of the building. Their permeability provides many air exchanges per hour to handle part of the ventilation requirements for fresh air. The mass of the walls makes heating easier. Robert Laporte of EcoNest Builders provided the skilled know-how and practical guidance needed to apply this ancient European wall system to the project.  The design considerations for light clay walls have been formalized by the  State of New Mexico Guidelines.  The small size of the building required only a few framing members, so it was easier and cheaper to build with a timber frame. Since I was concerned with groundwater contamination I built a concrete foundation and vault. To take advantage of the investment in all this mass, I surrounded the foundation with closed cell insulation. Because much of the foundation was above ground, I sheathed it with galvanized sheet metal for protection from the elements. I used a solar collector and direct solar exposure through south facing windows to heat the building. To prevent overheating, we had to exclude massive summer solar gain with a large south roof overhang.

I had to design in more ventilation capacity than natural convection alone could provide. Winter sun coming in through the windows heats a 10" metal solar "chimney". The solar chimney is effective only when the sun is low in the winter sky, however. In the summer a wind-driven turbine vent, of the type generally available for attic and roof ventilation, enhances airflow. A temperature-controlled automatic damper, sold as a companion to the turbine, regulates venting: it is adjusted to begin opening when the stack temperature reaches 50^oF and to open fully at 70^oF. (Since the original prototype, 10 inch dampers have been discontinued, only 12" dampers are available... see the Plan Updates for more info and changes.)  For an extra heat boost in the winter months, we converted part of the south glazing into a solar hot air collector, directing the heated air into the room.

When wind and solar are  not available, and the toilet space cools, the solar chimney will be chilled enough to create a backdraft into the space.  If this happens, odors will infiltrate into the space.  To counter this action, I designed the SunnyJohn with a second vault filled with football sized river rock at the base of the solar chimney.  The rock stores enough heat from the solar gain of the day that even with no wind or solar power, the solar chimney continues to draw odors from the space.  The stored daytime heat is available to drive the venting process up the solar chimney when the sun or wind are not providing a draft.    

Access for harvesting was only possible on the north side of this small building. We built a small ramp down into the vault, and used a regular cellar door arrangement for sealing it off. We placed 55-gallon plastic barrels for collection containers, modifying them slightly to our needs. The tops were cut off in such a way as to re-use them as well fitted perforated strainers on the bottom of each barrel. Each top (now the bottom screen) was drilled full of 5/16" holes and supported up off the bottom with a few broken bricks. The sides of the barrels above the bottom screen were heavily perforated with 5/16" holes on 4" centers for air exchange, and the very bottom has a ring of 3/4" holes for drainage. Each barrel had an initial 2" lining of coarse wood chip over the strainer to prevent solids from leaking. The portability and low cost of the containers ($10 as a "non-returnable, no deposit" item) makes it easy for us to cycle more of them into the operation if needed. The vault sizing is sufficient to allow for their use directly with shovel harvesting if you build a separating wall and modify the venting passages. Using the vault alone is an option, and would provide a 4 to 5 year cycle between the two chambers. 

The range of options in a moldering toilet is much wider than what I have built. If the toilet is to be integrated into an existing house, the scope of design alternatives changes. Ideally, the best arrangement will involve direct solar exposure to the vault, rather than the room. This means placing the room on the second floor, on the south side of the house, with the vault space at ground level. The venting can be setup to take better advantage of the sun and the wind, avoiding excessive solar gain to the room by rearranging the floor plan and using solar hot air exchangers exclusively.  With good ventilation design included in the house, the Sunny John can be the exhaust avenue for all of the house's incoming fresh air.  With that kind of approach, you may not need any solar driven venting options.  The house will do all the venting through the Sunny John chimney.

I used two stools in a side by side bench arrangement, but you can just as well have the two stools facing each other or the sealed unused stool area used as a small counter instead. You can build one stool on a small bench that is portable and seal the other vault at floor level. That way you will gain the extra floor space, moving the whole bench and stool to the opposite vault when needed. The toilet stools can be placed on the north or south side of the room, in the sun or the shade.  Remember that the fit and finish of the stools and benches must provide a fly-tight seal 

You need not feel bound to the idea of using portable containers. They've proven to be the best for many folks.  You can use two separate vaults built large enough so that they function well if their access allows for easy shoveling when it comes to harvest time. Vault design like this usually requires sloped bottoms and venting of the heap. Just keep in mind the basic requirements: space, ventilation (for odors and moisture,) heat (for breakdown and evaporation,) integrity (to prevent unwanted vermin and pests) and harvesting access.

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My first moldering toilet project (in 1993) involved the construction of a totally separate building, with it’s own foundation, framing and roof. If the toilet is included in a house design, most of this expense can be avoided. The cost of walls, roof etc will already be included in the basic construction of the home. The added cost of the toilet may only be some special hardware items. The building materials cost alone for my first design was only $357 off the shelf. New hardware costs came to a total of only $335. Since then I have contracted the construction of another moldering toilet locally for $1200 complete including paid labor. A slightly smaller arrangement entirely of recycled materials was designed for the sloping site of the Central Rocky Mountain Permaculture Institute.  It was constructed for a cash outlay of only $150!

The original moldering toilet, now dubbed "The Sunny John" is open for viewing Saturdays at:

Guidestone CSA Farm and Center for Sustainable Living
5943 NCR 29
Loveland CO 80538
Contact David Lynch at (970) 461-0271

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Occasionally Going Concerns Unlimited  offers weekend workshops detailing the construction and operation of a new Sunny John to grace the planet.  Keep in touch to hear about them as they are scheduled. 

Stay tuned for future workshops on all subjects related to Sustainable Living Practices..

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Workshop Fees have been $185 in the past.  It's a rate the builder/owner sets. They always included a copy of the plans to build your own!

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