Simple Waterless Toilet

Summary

I describe an on-going experiment in a waterless toilet installed in a small shed outside our main house.

Motivation

We live on an island that is its own sole-source aquifer. Water here is precious. The local water district has a backlog of approximately 90 people wanting water shares (calling it a waiting list would miss the mark) and, from what I've heard, no water shares have been granted in over a decade.

Our property includes an out-building which is currently only used for, and only suitable for storage. One obstacle to turning this out-building into habitable space is the lack of legal access to water. The second is lack of a septic system and the rather high cost of connecting to the sewer which currently serves our main house.

The biggest need for a sewer or septic system comes from "black water" - that is, water with poop in it, water from the toilet. Take out the toilet and one is left with "grey water": the effluent from showers and sinks. Thus a pre-requisite to one possible approach to making the out-building suitable for habitation is solving the poop problem which, in turn, initated the thinking that led to the current experiment.

Justification

One side effect of life on the island is many houses close to the water. Some of the older houses' septic systems are failing or, in some extreme cases, missing altogether. The problem is severe in some areas to the point where the water is so polluted the rich, indigenous sea life is both badly damaged and dangerous to eat - the oysters, clams and crabs are toxic from the sewage.

For the houses with enough land a new septic would cost over $10,000. For others, the sewage would need to be pumped uphill to a neighbor's land and the cost, assuming an easement for the use would ever even be granted, could run to over $100,000.

But then there's the thought: why are we using drinking water to carry shit into the sound? On some level it makes no sense. Others have written about this extensively, so I won't dwell on this point here. The summary, however, might be phrased as "waste not, want not." The result for me was increased interest in something simple, practical and waterless. There may be a greater good that could be served, thus, perhaps, my experiment, will be of interest to others.

Prologue

The obvious solution was to install a composting toilet, which led to a web search, which led to information and costs, etc. But I like doing things myself, so I was soon envisioning options ranging from a traditional outhouse, to an above-ground variation with two sides so that the composted manure could be collected and used on flower beds. My ideas eventually settled on an external Clivus Multrum as close to ideal. By the time I was done thinking I'd managed to dream up a project that would take me many months of weekends and probably cost several hundred if not several thousand dollars.

I'm a software architect by day, and my team uses 'agile' methodologies. The methodologies espouse several approaches, one of which is known as doing the simplest thing that could possibly work. Daunted by my imagined tasks, I asked myself that question. I read parts of the Humanure handbook online. I decided all I really needed to get started were some 5 gallon buckets, some sawdust and a camping toilet seat.

I posted for the buckets on Vashon Freecycle, got a response the same day, and voila, 6 buckets that should, by my calculus, be good for a month of "compost inputs."

Requirements

I knew the motivation, but wanted clarity about the goals. Here's a list in rough order of importance:

1. Health. Poop carries pathogens. It has to be handled accordingly. It should be noted that keeping water away actually makes this easier: water transports pathogens, spreading them 100s of feet. Keep the stuff dry (or drier) and it won't go as far.
2. Odor. Let's face it, shit stinks. Nature's wisdom makes us naturally inclined to stay away from the stuff. While most people think the water covers the odor, it has little effect. Odor is best controlled by ventilation, covering with solids (dirt), or, as a last resort, masking.
3. Appearance. Personally I don't like looking at other people's poop, and I don't imagine most others do either. One of the nice things about a flush toilet is that, in most cases, each customer sees a clear, fresh bowl of water ready to receive their deposits. It'd be nice if when using this waterless toilet, each customer gets a "clean start" so to speak.
   
4. Convenience. One thing about indoor toilets is they are convenient. Personally, I enjoy being outdoors, and a 50' stroll to the toilet doesn't bother me. But then again, I've not been going in the middle of the night, nor the middle of our rainy winter. Longer-term an indoor option would be good.
5. Hand washing. This is a sub-set of the health requirement. I don't, yet, have a decent water supply near the outhouse. Instead I rinse my hand with rain-water and come to the house to wash with hot water and soap. So, longer-term, indoor next to a sink would also be an improvement.

Reading about compost I was convinced that, done properly, composted poop is not a health risk. Instead the process effectively pasturizes the poop as thermophylic bacteria take over and super heat the compost to 160+ degrees Farenheit, killing off the pathogens which can't survive at that temperature. Leaving a long 'curing' period of 1-2 years acts as a second mitigator of health risks as othe organisms eventually out-compete the pathogens and result in humus which does not support pathogen growth.

The Plan

The land has a pre-existing "outhouse" structure. It previously housed a small chemial toilet which was powered by a 12-volt car battery. The former owner used this in summer for a camp she ran and dumped the contents down an additional (though apparently illegal) sewer hook-up.

The plan was to use this structure and place a 5 gallon bucket inside with a toilet set attached and a second bucket nearby full of sawdust. The sawdust is used to cover the poop which reduces or even eliminates odors. But that's a side-effect as the main need for sawdust is to help in the making of the compost: it adds carbon to the nitrogen-rich human waste, and it adds air-trapping bulk, key for aerobic composting.

Talking it over with my skeptical wife, Amy, who otherwise wanted nothing to do with the project, she reminded me that squatting is a more natural position for pooping. She'd lived in Africa for 2 years as a Peace Corps volunteer and whie she said she'd grown to love her "hole" while there, she had no interest in going back to that experience... Still, given the squatting, I realized I could dispense with a toilet seat altogether and just use the bucket, some cinder blocks that we had on hand would serve as steps and a "platform" so that one's feet were at the level of the bucket-top.

Setup

Ingredients:

1. Two 5-gallon buckets
2. One large sack of cofe husks - they were free and I couldn't find any sawdust nearby
3. One old empty plastic squeeze bottle, to hold water
4. Six cinder blocks - for steps and for the "platform"
5. One pre-existing "outhouse" - if I didn't have this I'd have done the whole thing outside so long as it was summer - perhaps with an umbrella nearby - and evaluated how well it worked before investing the effort in constructing an outhouse shed.
   
6. One roll of toilet paper and holder (came with the outhouse)
7. One electric lantern (optional)

The whole thing took me about 15 minutes to set up. Most of that was placing the cinderblocks. The result is in the photo.

Operation

It's essentially just like any toilet except instead of sitting one squats. If you've ever used a "Turkish toilet" - e.g., in France - or have ever gone camping and squatted over a hole, then you're familiar with the posture. According to most it is a more natural and comfortable posture. Personally, I find the two interchangeable.

Although usage is pretty obvious, here are the detailed steps:

1. Open outhouse door.
2. Remove lid to bucket.
3. Climb up stairs - if you're wearing pants you may want to take them off and hang them on a hook first.
4. Squat over the center of the bucket.
5. Make your deposits, including toilet paper.
   
6. Water down the TP with the squirt bottle.
7. Cover everything with a layer of bulking material (coffee bean husks in this case).
8. Replace lid. I generally do not put it on tightly. I then turn the bucket a 1/4 turn so it's ready for the next customer.

Conclusions

My experiment has only been going on for 2 weeks. I don't use this toilet exclusively and, over the two weeks, I've almost filled one bucket. So far there's been no odor when I come into the outhouse. There have been no pests nor flies either. I think both of these absences are due to thoroughly covering the poop with bulking material. Since I plan to combine the human waste with kitchen scraps I am confident there will be plenty of nitrogen in the compost mix to offset the carbon from the extra bulking.

In short: so far, so good. I plan to collect two full buckets and then build a proper compost bin, a la the 'Humanure Hacienda' though, once again, I aim to start with "the simplest (and cheapest) thing that could possibly work - so it may be 3 shipping pallets which I got for free and 2 bails of hay to hold one side and some extra bulking material. I hope to post again once I'm at that stage.

Notes

According to local health department codes, even grey water systems require a full septic installation: tank and drain field, albeit their sizes are reduced from what's required for handling poop. If careful about what one puts down the sink a full septic system is overkill. This is especially true in a vegetarian household since raw animal products are another source of pathogens commonly going down a household drain. Of course we don't legislate the diet of a house's occupants - we oursleves are not vegetarians - thus the health code wisely errs on the side of caution. The other thing to be careful about putting down a drain are chemical toxins, but that's pretty much true regardless of the septic/sewer connection in use.