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Composting Toilet Composting Toilet
Compost Toilet

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Composting Toilets – The No Bull#$% Guide To the Ultimate Green Appliance

General Product Features

After a decade of being intimately acquainted with composting toilets, I’ve got some pretty good stories to tell and quite a few anecdotes to share.  While I no longer work in the field, I find myself returning to the topic over and over again, like a bad record.  The truth is, everyone wants to talk about composting toilets – and how they can make the process of dealing with “it” a little more environmentally friendly. 

I’m not going to lay any claim to having studied extensively in the self composting toilet field, as I would have required about 3-4 different degrees to do so.  I am going to tell you that I have helped thousands of people with their composting problems and shared their stories while working at one of the top manufacturers – from that I draw what is probably a little more expertise than the average bear.

How Do They Work?


All composting toilets work off of one central principle.  Aerobic bacteria, which are bacteria that thrive on oxygen-rich conditions, break down waste quickly and without any unpleasant off gassing.  Anaerobic bacteria, by contrast, are the bacteria which break down waste in a septic tank; this breakdown process is much slower and anyone who has been around an open septic can tell you just how lovely it smells.  Composting toilets really do produce a safe, innocuous, and dirt-like material when the process is complete – as long as a proper maintenance schedule has been followed.

Aeration, Carbon, & Moisture


The catch – a good environment is absolutely necessary for the aerobic bacteria to do their work. This is where all of the different designs and products come into play.  The waste requires aeration, which is provided through various design principles, stirring mechanisms, and occasionally fans. 

You must also ensure that adequate carbon is provided to the mix, since any good compost requires an adequate carbon/nitrogen ratio, and urine is very high in nitrogen.  This is done through introduction of carbon rich materials like peat moss.

You must also make sure that the mixture is 40% to 60% moisture content.  Too dry, and the composting process stops and you have a desiccating toilet rather than a composting toilet.  If it is too wet, you will have a mini septic tank in your bathroom.

The Rest of It


Any liquid waste is evaporated off by means of fans and heating elements, and any excess liquid is drained out to a French drain (gravel bed) system.  In systems that function without any electricity, all liquid is drained off. 

How does it help the environment

Most composting toilet models work without water, and those that do work with water as a concession to societal needs for a flush toilet use extra low flush toilets. 

One dry composting toilet alone in a house can save, on average, 98.7 litres (that’s 26 gallons) PER DAY in freshwater use.  That is the average per capita household use of water for toilet flushing in Canada.  That is over 36,000 litres of water per year.  There is no doubt that just installing one composting toilet can make a difference, no matter where it is going.  For that reason alone, composting toilets are worth anyone’s consideration. 

If you want to take it a step further and purchase one without electricity, you just need to ensure that you install a secondary system to deal with excess liquids.  Details on such systems are usually available from the manufacturers.

Product Details

If you have a cottage or cabin, and want to limit the flow to your septic; or simply have a more conveniently located bathroom at your shoreline rather than up a hundred stairs in the main cottage, you can probably use a composter. 

If you are determined to set up a composting toilet for your family for your main house, keep the maintenance in mind (3 times a week for most designs, any claims to less than that should be investigated prior to purchase) and the fact that there is more of a chance that you will be personally involved with your poop than if you were to install one at a seasonal cottage.  You should also investigate your local building laws if you think that there is a good chance that an enforcement official will drop by, and make sure that you have a proper solution for your greywater (shower and sink water).  Don’t let it just run out onto gravel, particularly if you are using detergents, etc.  This will do more harm than good. 

Capacity is also very important when selecting a composting toilet.  Make sure that you are getting one that is large enough for your needs.  If you are looking for one for a commercial or civic application, look at larger systems.  They work really well in parks and any other setting where you require a system that maintains the ecological principles necessary for a place such as a national park. 

Product Description

I could really go on a lot more about composting toilets.  In the interest of keeping things simple, I will say that they are one method by which you can lead a more environmentally friendly lifestyle.  They may not have a direct impact on the issue of climate change, but they definitely save water and minimize the risk of harmful bacteria and nutrients ending up in our precious drinking water systems through leaky septic tanks; most septic tanks remain viable for an average of nine years, and most of them have been installed for much longer than that. 

Product Review

Do They Work?


This is usually the first question everyone asks, so best to get it out of the way.  The functionality of a composting toilet can be broken down into two parts – 20% is design-dependant, and 80% is user-dependant.  The answer is yes, if these two items are successful.

Design

I’m not going to say which designs work better than others, because I would definitely be accused of favoritism, and perhaps rightly so.  Most of my experience was with one design. 

The one thing I will say about design is that you should purchase from a company with an established reputation in the business; there are quite a few upstarts who are hoping to break into the field with new designs now that “going green” has become a major profit center, but when it comes to your bathroom, why take the chance.

User-Dependant

Any composting toilet, regardless of the design, is heavily user-dependant for proper operation.  Even the ones that claim to be automatic still need a human eye to monitor moisture levels, etc.  Basically if you aren’t prepared to look at your own poop, whether it has decomposed or not, you aren’t a composting toilet person.  Composting toilets also require addition of bulking material (the carbon mentioned above) and aeration, whether through agitation of stirring mechanisms or manual aeration. 

What to look for when buying

All of the tried and true designs have been patented, and any room for improvement really only exists within the scope of those companies.  That isn’t to say that anyone with a brilliant new idea should immediately scrap it, but in my view most of the newer entries into the marketplace are simply overpriced boxes with fans, or designs which cannot lay claim to being composting rather than desiccating (drying) toilets. 

The difference between the two is crucial – bacteria aren’t breaking anything down in a desiccating toilet, meaning that the end product isn’t exactly inert, and toilet paper is still extremely evident.  You don’t want that.  If you do any solid research on the process of composting itself, you will quickly turn up that moisture is an essential component of the process.  This is the one area in which dry does not equal sanitary. 

You also should watch capacity claims and marketing jargon.  A good rule of thumb to use is to purchase a product that has 25-40% more capacity than you think you need in order to both plan for the future and allow a margin of error.  The biggest is the best.  Often the price difference between smaller and larger models is negligible; don’t save $200.00 now and find yourself in a bind when your kids move back home three years later.

Who Should Buy Them?


Composting toilets are not for the faint of heart.  While what comes out at the end is usually decomposed dirt, there is going to be at least once in the lifetime of the product that you will have to deal with the raw stuff, regardless of any manufacturer’s claim.  Things like repairs to parts require your involvement in the main chamber in most designs.  If you don’t think that you can hack that, best not to purchase one.  Don’t think that you can hire a local handyman to do this for you either – most won’t touch it because they aren’t familiar with them, and in a lot of cases I have heard of repairmen doing more damage than good when asked to replace a part in a desperate bid to get in and out as fast as possible.

Marine composting toilets are starting to get a bit more attention.  It is my experience that the space limitations of boats preclude their use; a chamber larger than possible is necessary for proper full-time use for two people.  If you are a solitary sailor, they are an excellent option.

References

  • Study on Waterless Composting Toilets, Australia
  • http://www.clearwater.asn.au/resources/523_1.322_TD_JW_DavisonCompostingtoilets.pdf
  • Wikipedia Article
  • http://en.wikipedia.org/wiki/Composting_toilet
Submitted by angelawest on Aug 6, 2008