The hot poop on alternative toilets, Tiny house edition

After covering the wonderful Tiny Tack House, Commenter Marrena noted:

A bucket and sawdust! That's pretty hillbilly for most people. I see that the other similar tiny home you feature here, Alek Lisefski's Tiny Project, also did the bucket and sawdust routine. There has got to be a better solution.

I have twenty-five years of experience with alternative toilets, but have never looked seriously at the bucket and sawdust toilet as a viable alternative. In fact, re-reading Joe Jenkins' Humanure Handbook after many years, I began to appreciate the logic and sophistication of this solution. (Sami has covered this for years, links at end of this section)

Humanure and the Loveable Loo

© Human nutrient cycle/ Joseph Jenkins

Much of the Humanure Handbook is taken up with a review of the problem of what we should be doing with our poop, and the alternatives available for composting toilets, many of which are big, expensive, requiring electricity and pretty regular maintenance. Jenkins' system is a model of simplicity; it's a bucket. You put organic material on top of your poop after you use it; if it smells, add more sawdust or whatever you are using until it doesn't. The buckets fill up pretty quickly (in less than a week for two people) at which point you swap it out for an empty one and take the full one out to the separate composting area outside. It's that simple.

© Loveable Loo Instructions

It is usually a do-it yourself thing, but you can get the package deal with the Lovable Loo.

When any foul smelling material is deposited into a humanure toilet, it is covered with a clean organic material in order to prevent odor, absorb moisture and prepare the material for composting. This is how humanure is mixed with the other organic materials — by covering. No manual mixing, stirring or digging of the humanure is required, only covering. Therefore, the clean organic materials used in the toilet are called “cover materials.” The cover materials used in the toilet should have a somewhat moist (not wet or dry) and fine consistency. Sawdust from logs that are sawn into boards is ideal, but other materials can be used depending on what is lo- cally available. Some people utilize rice hulls, coco coir, sugar cane bagasse, peat moss, rotted leaves, even shredded junk mail. Proper cover materials are absolutely essential to the successful operation of a humanure toilet.

There's a lot more information on the Humanure website, including PDFs of the book that you can download.

Sami Grover has covered the Humanure scene, and the lovable loo before; see also:
A Composting Toilet for $195 - the Loveable Loo (Video)
TreeHugger Tips: How-to Manage Humanure Composting
DIY Composting Toilets and Humanure: The Pee & Poop Show (Video)
Joseph Jenkins Explains Humanure Composting

Other alternatives: Pluses and minuses

One of the reasons that I am intrigued by Jenkins's solution is that none of the alternatives are truly plug and play, they all require adaptation and maintenance. The major manufacturers are all striving to make it more like a home flush and forget experience, but they are not there yet. Here are some options for small spaces; since we are discussing toilets for tiny homes I am skipping the bigger units.

The Chemical Toilet

© Chemical toilet by Dometic

These are often two part units with a toilet above and a tank below that you can separate and take to the pump-out in an RV park. They are environmentally the worst solution, where you pickle your poop in formaldehyde to keep down the smell and till you can get rid of it. The trouble is, everything smells of formaldehyde. Not recommended for other than short term use or if you are constantly on the road and have access to legal places to dump the contents.

The Incinerating toilet

© Incinolet

The Incinolet is built like a tank for industrial use, all stainless steel. You drop a sort of coffee filter into it and then press a pedal; The full cone of poop then drops down into a lower chamber where it is incinerated by a high temperature electric heater.

© Incinolet

Powerful fans carry the smoke and vapour away, supposedly after filtering out much of the smell. It uses a LOT of electricity, and if there isn't a breeze, the air is full of the smell of.. burned poop. The fan is extremely noisy; it's like having a 747 going in your cabin. A friend's young child used it and was put off toilet training for a year I think.

Small composting toilets Sun-Mar

© Sun-Mar

The Sun-mar composting toilets are very popular, and come in compact units. It has a composting drum that you add peat moss or other composting material to and then crank to mix everything up; crank it backwards and it drops into a finishing drawer. Because it's all mixed up, it feels more like compost and less like poop in a shorter period.

This unit is small and recommended for "light residential"; their standard units are higher and have a step up. It needs an "emergency drain" to handle moisture in excess of what the evaporator can handle. There is also a larger off-the-grid model without a heater that can be hooked up to a 12 volt fan and solar power. Laurence Grant has been using one in his house for almost twenty years.

Envirolet

Envirolet Toilet/CC BY 2.0

This is a version of the Envirolet toilet that I am using now in my cabin. It is a lot lower than the Sun-Mar because it has no drum: the Envirolet people say that mixing everything up all the time kills the composting action. So the stuff just sits there; a rake mechanism spreads it around. The fan and the heater are effective at keeping it odorless and it runs all summer without needing to be emptied. However by the end of the year the poop is feeling uncomfortably close beneath you.

Mulltoa / Biolet

© Mulltoa

I have always been impressed with the design of the Mulltoa, sold in the States as the Biolet. I wrote last year:

They have tried to make it as much like a conventional toilet as possible and for a self-contained unit, do a pretty good job of automating the process. Sitting down on the toilet activates the trap doors; closing the seat activates the" the stainless steel mixing mechanism that efficiently breaks down paper and distributes moisture into the compost material in the upper chamber." It now comes with LED indicators that tell you when it is time to empty the unit, and when it needs the thermostat turned up to evaporate the excess moisture.

I have been told (by a competitor) that the stainless steel mixing mechanism, buried as it is in the poop and compost, is a high maintenance item.

Meanwhile, back at the Loveable Loo...

All of these systems need electricity, cost about two grand, are not maintenance free and are a lot more complicated that the Humanure system that costs between zero and $ 225 for the whole purchased package. None of them do the job perfectly, but I am no longer certain that they are all that much more effective than the Loveable Loo. I am going to follow up with the Tiny House occupants and find out what they think of all this.

Tags: Composting | Composting Toilets | Toilets