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Compost Toilets Explained
Many people now know about composting toilets, particularly those in the alternative movement who are quite familiar with composting in their gardens, and who understand the advantages of recycling and simplification of our needs.
But to the many others who have not really thought about where their sewage goes after flushing, the thought of composting their own waste is a little uncomfortable.
Objectionable questions are fired at you when you first introduce the concept to someone, and many persons leave the subject still thinking that a composting toilets is a old pit (outhouse) toilet, remembered unpleasantly from camping trips.
Well, composting toilets are far from being pit toilets! They range from simple twin chamber designs through to advanced systems with rotating tynes, temperature and moisture probes and electronic control systems.
They are effective biological converters of human and household “waste,” saving money and energy for the person and community. They start the regeneration of the Earth’s precious environment that is long overdue.
The Benefits of Composting Toilets
Making a Big Difference
The advantages of natural waste treatment systems are many and varied.
The following section shows the benefits of the system in comparison to existing waterborne waste treatment systems. These benefits improve conditions for the individual, the community and the environment.
An understanding of how your system benefits the individual and the community will help you to maintain it and confidently explain it to others.
Benefits to the Individual
There are many great reasons to use a composting toilet!
Water Use Reduction (20-50%)
A significant savings in water storage will result if the household is not on reticulated water supply. Combine this with wastewater re-utilisation in irrigation and other household water reduction techniques and water storage costs can be cut by up to 60%.
Shock Loading Capacity
Loading shock for large gatherings is achieved easily with correctly sized composting toilet systems.
Odour Problems Reduced
The suction air flow in most composting toilets takes toilet and bathroom odor out of the room and acts like a constant extraction fan.
Lower Household Maintenance Costs
Sewage rates and water rates (metered) can be in the order of $500 per year, a significant cost. This will only increase if the demand for sewage system upgrading increases. Other on-site systems have annual maintenance costs that are obligatory. Local authorities will be increasingly paying rebates to households who own composting toilets.
End Product Recycled
While only small in amount, the solid end product is a valuable humic fertiliser that can be utilised around trees and gardens.
Reduced Greywater Loading
Where composting toilets are installed instead of septic and mini-treatment systems, there is a large reduction in the “loading” on the effluent treatment system by the removal of “blackwater.” Smaller, less maintenance, greywater systems are possible.
A household with a composting system is independent from potential problems of the waterborne sewage system. If future water shortage or system backup problems occur with conventional systems, there is not much that you can do personally about it. On-site composting systems are much more flexible, they are easier to fix and have less damage potential if operated incorrectly.
The composting toilet possesses the ability to recycle much of your household waste. Food scraps, paper, lawn clippings and grease from you grease traps and greywater systems can be composted back through the toilet. If you choose to put in a reed bed greywater systems, the annual clippings can also be composted. There is no wastage in this system.
Composting toilets can be installed in many different situations which would not accommodate other systems. Rocky sites, high water table, no water storage, environmentally sensitive, close to running watercourses, and swampy ground. All these difficult site situations can be accommodated with a small amount of alteration to the basic system design.
Benefits to the Community & the Environment
Together with the personal benefits of the composting toilet there are overall benefits to the society and the environment.
A reduction in water use allows the large capital costs of dams and reservoirs to be spread over a greater population. It also enables decentralized water sources to be used.
Reduced Marine Pollution
Nutrient load on streams and rivers is almost negligible. This results in more oxygen being available in the water and a return to improved activity of marine life.
Pollution Detected Quickly
Without sewage systems to flush away wastes, It would be easier to ascertain where toxic wastes are being leaked into watercourses. Industry would be more willing to rectify these problems if it were easier to identify the sources.
Miscalculation in individual composting systems has a much smaller impact than the same mistake in a large centralised system. It is also easier to rectify and return to normal operation.
Flexibility of Planning
Composting toilet systems are built only when the need arises. The high headwork and treatment costs of conventional sewage systems must be borne by the community ahead of development. If development does not go as planned, then money is wasted.
Less Environmental Impact
Compared to sewage systems, on-site composting and greywater treatment has less impact on the environment:
• Large effluent releases into watercourses and oceans are avoided.
• Disruption to soils systems through pipeline installation is eliminated.
• Leakage of raw sewage into groundwater through pipe deterioration and breakage is eliminated.
Flexibility in Estate Planning
By eliminating the planning constraints of the sewage system underground piping and infrastructure, housing developments can be designed with more emphasis on environmental and social considerations, rather than how best to situate the blocks to make pipes run straighter.
For such a simple technology, the benefits to the individual and to the community are quite amazing!
What is a Composting Toilet?
On Site Waste Treatment Plants
Composting toilets are toilet systems which treat human waste by composting and dehydration to produce a useable end-product that is a valuable soil additive.
They come in a variety of models and brand names as well as different shapes and designs to enhance the natural composting process.
They use little or no water, are not connected to expensive sewage systems, cause no environmental damage and produce a valuable resource for gardening.
The systems can be broadly divided into two different types:
With the batch systems, a container is filled and then replaced with an empty container. The composting process is completed inside the sealed container. The system may have a single, replaceable container. Or it may be a carousel system where 3 or 4 containers are mounted on a carousel and a new container is spun into the toilet area when the other is full. After a full cycle is complete, the first container is fully composted and ready for emptying.
CONTINUAL PROCESS SYSTEMS
These systems are in a constant state of composting. Waste enters the system, composting reduces the volume and moves it downward where it is harvested after 6-12 months as fully composted material.
All systems are designed to treat the waste material by composting, worm processing, micro- and macro-organism breakdown, and by dehydration and evaporation of moisture.
There are a wide variety of systems including:
• Owner-built, two chamber mouldering systems that are basic, but effective.
• Owner-built from concrete blocks and concrete inclined base. Constructed in with the house foundations.
• Manufactured, small, self-contained and remote systems suitable for vacation and full-time home use.
• Manufactured, large tank, inclined base models suitable for heavy loadings.
• Wide variety of small units which fit into existing bathrooms. Many have dehydration fans and heaters.
• Vacuum flush unit for production of worm castings.
• Full flush systems with centrifugal action to deposit wastes into composting chamber.
Not all of us live within the city limits and this means we either have to use a septic tank or be creative when it comes to eliminating our waste. Neither do we want to touch it nor do we want to impact the environment any more than it already is. Septic tanks work fine if you aren’t in the city’s sewer system, but depending on the restrictions of your health department, you might have lagoons or sprinklers or chlorinators all tied up in this “simple” system – and it’s suddenly not so simple anymore.
This got us thinking about the various types of chamber pots available and thought we’d offer our readers a couple of alternatives.
As the name implies, composting toilets take waste, both fecal and liquid and turn them into compost. How it works is actually rather interesting, if this sort of thing fascinates you. First it separates the solid from the urine – solid stuff falls into a composting chamber and the urine is sent to tank called a gray water system. Earthworms, microorganisms, air and heat all work together to start decomposing the solid matter. Meanwhile, the urine (as you may remember from your biology and chemistry classes) is comprised mostly of nitrogen. If you were to look at the ingredients of most fertilizers, you will notice that they contain lots of nitrogen. When you are ready to add your new batch of compost, having stored your urine, sprinkle it all over your plants and watch them drink it up.
Now all the rage in England, parts of Europe, Australia and New Zealand, one might assume this is a new concept; however, a rather crude version dates back to the late 1800s. The notion of using excrement as a form of compositing is controversial. Many countries allow this, and even in the USA there are areas where “sludge” (human waste) is sold to farmers for fertilizing crops, but is that really healthy? The Chinese have devised a system for using human waste, but part of that system involves high heat for about a month to kill off deadly bacteria and organisms. There are too many diseases that can be transmitted via human waste if the composting is not done right. If you choose to go this route, make sure you’re composting properly and applying it to your crops in the prescribed manner.
The nice thing about composting toilets is that they use almost no water to operate.
Who Sells These?
Available in both electric and gas powered, these are toilets that burn excrement rather than flushing it. These are seemingly ideal in remote areas, for people who live off the grid and/or have unreliable plumbing. They are available in various sizes and can run on electricity, diesel, propane or natural gas. The diesel versions boast the ability to burn between 1 and 7 gallons of waste an hour. The model you purchase will determine how many gallons can be incinerated. Another of their advantages is that unlike a septic, enzymes are not required to kill bacteria – another euphemism for human waste.
The logistical difference between the gas and electric version is that every so often you will need to empty out the ashes that are burned – the level accumulated that requires emptying varies by manufacturer.
A few manufacturers make these incinerating toilets in gas powered:
And for the electric powered ones – I recommend you consider an alternate source of power (such as wind or solar) if you are going go this route, as your utility bill will likely increase and not decrease:
Other Alternatives to Traditional Flush Toilets
After a careful review of the other alternatives available, they really didn’t turn out to be viable alternatives after all. Perhaps easier to install, they appear to be damaging on the environment, non-hygienic or wholly inconvenient.
Perhaps if you live in an RV park or on a boat, the portable toilet, a.k.a. the port-a-potty, might be a solution for you. Enzymes are required to control odor and more importantly kill bacteria that could be harmful. Once the tank is full, somebody has to come and haul your waste away.
Digester tanks work by breaking down waste to be used as fuel and/or make humus. Nearly as I could discern, great as they look, they seem to work best in highly industrialized areas (due mostly to their size). They can hold up to 1000 gallons of waste. Most of us don’t have the land to house something that large.
We hope this article was helpful to you. If you own one of these systems, we’d love to hear your feedback. It’s okay, as the story goes, everyone poops…
We may as well talk about it.
Composting toilets have come a long way in the last two decades. The first composting toilets were outhouses, at one time the ubiquitous outdoor bathrooms used by most western families. Here are some of the best composting toilet systems around, each with their own modern-day twist on an age-old concept:
Sun-Mar Composting Toilets
Sun-Mar is probably the best-known composting toilet maker in all of North America. Their design puts the toilet unit inside the bathroom with the composting chamber and ventilation pipe sitting outside of the house. Another unique part of the Sun-Mar system is the composting chamber, which rotates like a cloths dryer. This allows oxygen to get to all of the contents, thus keeping the compost aerobic, which speeds up the rate of decomposition.
Like most composting toilets, there is a separate chamber called the “finishing drawer” where the aged compost sits awaiting removal. Some online reviews claim that sometimes fresh waste falls into the finishing drawer in Sun-Mar composting toilets, which results in finished compost that may still contain pathogens and retain an odor. However, due to the design of their system (the drum only turns one way) I don’t see how that could be possible. Furthermore, Sun-Mar systems are certified by the National Sanitation Foundation International, which requires finished compost from toilets to contain less than 200mpn/gm of oderless fecal matter.
BioLet Composting Toilets
BioLet makes an interesting composting toilet. It differs from others in several ways, such as requiring an electric source for heating and evaporating the liquid and a set of “trap doors” that automatically open when you sit on the toilet. For women, this might sound like a great idea. Who wants to look down at the “compost” after all? But for guys – who don’t sit down to urinate – it might take some creative foot placement to apply enough pressure on the seat for the trap doors to open.
BioLet composting toilet designs are compact and put the composting chamber inside the house, directly under the toilet in a “bucket-like” design. They do have a tendency to over-dry the compost, which makes it difficult sometimes to stir the compost (which is necessary to prevent anaerobic conditions) using the externally-accessible stirring rods.
Clivus Multrum Composting Toilet
The Clivus Multrum composting toilets require a large accessible space below the toilet itself, typically located in the basement. Their waterless design (they also have a foam flush) relies on gravity to move the “compost” down a ramp. It includes an automatic moistening system, which requires the system to be connected to a water supply, even those it is a “waterless flush” design.
It also has to be connected to power in order for the liquid removal system to work, which removes liquid from the main chamber of the composter and sends it to a separate storage tank. Due to the size, complexity and cost of this system it is not on the top of our list in this review. But that is only because this review is focused on home-use toilets. For industrial purposes, Clivus Multrum may end up coming out on top.
EcoTech Carousel Composting Toilet
EcoTech toilets are made for full-time use for entire families, as opposed to some of the smaller designs like many of the Sun-Mar and BioLet models, which are designed for cabin and vacation home use. This design is multi-chamber (usually four) and should be rotated when full, which takes from two to six months. This means one “batch” of composting material can age for up to two years.
It also means no “fresh” material can mix with the older material, thus ensuring that more pathogens are destroyed and you get a cleaner end-product. The EcoTech composting toilet system is usually set up with the composting chamber in the basement and a ventilation pipe running up from the chamber through the roof or wall of the house.
The Envirolet composting toilets are a last-minute addition to this composting toilet review / comparison, but are definitely worth looking into. They are good looking units that are designed at different sizes and prices depending on your needs, but all of them have the first Vacuum Flush technology we’ve seen in a composting toilet.
All of these composting toilets are high-quality systems by trusted manufacturers. Although it is a tough choice, in the end we would recommend a different system for three different needs and price ranges:
- Best for Industrial and Municipal Use:
- Best for Small family (3-4 people), Cabin or Vacation Home Use:
BioLet or Sun-Mar
- Best for Large family continuous use:
- Best for no-basement use: Envirolet
In this review we compare composting toilets from what we believe to be the best manufacturers, each with their own unique design to human waste compost.
Sun-Mar Composting Toilets
- Outdoor Composting Chamber
- Rotating Drum for faster composting
- Requires electricity for heater
- Widely available
- Many sizes
Avg. Price: $1,500 (and up)
Learn More: See SunMar Composting Toilet Models
BioLet Composting Toilets
- Single Unit System
- Larger models require electricity for heating
- Trap doors
Avg. Price: $1,300 (and up)
Learn More: See more BioLet Toilet Models
Clivus Multrum Systems
- Large system
- Waterless and Foam-flush designs
- Requires electric and water
Avg. Price: $10,000 ? Company does not list prices
Learn More: Clivus Multrum Site
EcoTech Carousel Composting To
- Multi-chamber composting
- Separate composting chamber
- No heating element
- Ability to age compost up to two years
Avg. Price: $2,700 (and up)
Learn More: EcoTech Website
Envirolet Composting Toilets
- FlushSmart Vacuum Flush
- No gravity required
- Modern, elegant design
- 10 persons per day for vacation use and 8 persons per day for continuous use. (Based on 3 uses per person per day.)
Avg. Price: $3,500 (and up)
Learn More: See Envirolet Models