December 7, 2007 4:11 AM   Subscribe

I was a bit inspired by this post to think about what kinds of composting toilets are available for a poured-concrete apartment building in the middle of an urban area. Am I nuts for even thinking of it? Even if I could, wouldn't the stench ruin us? Or what are the technological barriers preventing these systems from being smaller than they are?

The girlfriend and I are 4 months away from moving into our new place, and as there simply IS NOT such a thing as a separate-standing home in Beijing, we're looking at ways to make our new abode a little less polluting. It's a standard, cut-rate poured-concrete apartment, we're on the top floor (which means that given the proper permission we can install things on the roof and hang things off the side of the building), and it's a two-floor penthouse with 3 bathrooms (in line with the usual overabundance of toilets common in floor plans these days). The water pipes are already connected,'d be nice if we didn't have to use them. Do I have any options?
posted by saysthis to Home & Garden (8 answers total) 2 users marked this as a favorite
Uh. I would say that centralized management of your crap is both the most efficient and eco friendly alternative in any urban area.

Where I live the buses will run on biogas fermented from my shit (right now the shit just heats a sizable part of the city). If it's not to mercury infested whats left is perfect fertilizer (otherwise you just burn it for heat/electricity).

If you want to reduce your footprint you should consume less energy. You could get a roof garden. Those are nice and you'll be able to take a crap in it once in a while.
posted by uandt at 5:09 AM on December 7, 2007

What uandt said. Municipal sewage treatment reaps huge efficiency benefits from it's scale.
posted by phrontist at 6:07 AM on December 7, 2007

For both environmental and public health reasons, it is better to not be the "odd man out" in town. You could (in theory) convert an entire city, or at least a huge sector of a city, to composting toilets -- but to really get those gains you need all the infrastructure of specialized waste-removal crews, trained compost toilet repairmen, etc. What you don't really want (or rather, if I were your neighbor or worked for the public health system, I wouldn't want) is someone making it up as they go with their feces -- lots of public health gains in modern societies rest on the scrupulous separation of feces and people, which flush toilets perform very well. As you are no doubt aware, they also use lots of water -- but any solution to this needs to be a) city-wide and b) just as effective at separating people and feces.

Lots of people have proposed plans for getting away from water-born sewage on a large scale, but as far as I know almost nothing has ever been built on a scale larger than an apartment building in a developed country. (Huge cities of many millions of people in the developing world have grown without centralized water-born sewage, but that comes with a bunch more problems, and is a different discussion. And until not that long ago, and perhaps in some areas still today, many people in China relied on night-soil workers coming every day to carry away the fresh buckets of waste, but that also comes with a different set of problems.) Partly that is because the public health people and the civic engineers are really conservative, reluctant to give up a system that they know works for one that might turn out not to be very good in practice, just to save some water. And a lot of it is that flush toilets are heavily demand-driven -- people genuinely like using them better than pit toilets, composting toilets, buckets, etc.

And lastly, there are real inefficiencies in building parallel infrastructure systems. That is, if you already have a water-born sewer (centralized, or just a septic tank for the building), spending money and fuel and materials and time to build, maintain, and service a parallel composting toilet set up doesn't really make sense, environmentally or otherwise.

All that said, it is easy to do a variation of a composting toilet in an apartment. The easiest and lowest tech option (great for emergency situations) is a "sawdust toilet": a five-gallon bucket with sawdust in the bottom; you just cover each new "addition" with more sawdust (which you can get free from any carpentry shop or sawmill). When the bucket fills, you cover it and and start a new bucket; eventually you will need to find a place to put the semi-composted waste. (Note also that most composting toilet systems require the user to change their behavior, including things like separating urine and feces, etc, so you will need to be ready to explain all of this in graphic detail to every visitor.) And you can go up in fanciness from there -- but each comes with that issue of "what do you do on the fifth floor of an apartment building with a year's worth of composted feces?" -- really, that is a question for which it is better to have an answer at the beginning than to think about at the end.

The Wikipedia page on composting toilets is pretty good, as are some of the pages it links to, like this one and this one. Here is some research on large-scale urban implementations of these sorts of toilets.
posted by Forktine at 7:31 AM on December 7, 2007

Have you considered a semi-graywater system, where you save water out of either your shower or sink into a bucket and pour it directly into your toilet whenever you would like to flush? This has a lot of benefits... Low cost! Low impact since the water would be going down the drains anyway. Clean. Fairly easy to use, your shower and sink are already conveniently located near your toilet. Since all of the original plumbing is hooked up (or mostly hooked up), you don't have to instruct guests about what to do when they poo...
posted by anaelith at 8:26 AM on December 7, 2007

You might want to google something like "self-contained composting toilet". There are stand-alone units that can go pretty much anywhere. They claim to be odor-free. They are expensive (and are heavy and would be expensive to ship) and mostly they require a consistent source of electricity (non-electric models must be vented to the outside). Frankly, this is probably a bad choice as far as enviro-battles to pick as an apartment-dweller in China go.
posted by nanojath at 9:29 AM on December 7, 2007

(Note also that most composting toilet systems require the user to change their behavior, including things like separating urine and feces, etc, so you will need to be ready to explain all of this in graphic detail to every visitor.)

This is important. You should use a composting toilet before you consider them, because they are different, and some people are uncomfortable with thinking at all about what they are doing on the toilet, and where does it go. Besides, if you don't have a garden, where are you going to put the compost?
posted by oneirodynia at 10:37 AM on December 7, 2007

Oh, you're not nuts for thinking about this stuff. Fouling our water with waste is going to be more and more of a bad idea. I do think you can implement some of the grey water systems. This recycled water toilet is easy and non scary to landlords and users alike, and doesn't require a garden for grey water recycling.
posted by oneirodynia at 10:40 AM on December 7, 2007

After I left for university my mother and stepfather moved into a house with a humus toilet, which looked a lot like this.

I wouldn't say I loved it, but I got used to it. All that was required was a vent to the outdoors. There was a stirrer you had to use nightly to mix up the new stuff with the old stuff. There were often fruit flies in the bowl but they didn't seem to be interested in the rest of the bathroom or the house.

Essentially the thing just looked like a bigger, higher-sitting toilet. When you lifted the lid, you would see two white flaps that covered the business below. When you sat down, the weight on the seat caused the flaps to open up, so most of the time you didn't have to observe your housemates' digestive concerns. There was no real smell, except once in a while I remember a smell where the exhaust fan was outside.

Based on my knowledge I can't see why you couldn't install one of these in your apartment -- I assume cutting a vent wouldn't be a problem. And as far as disposing of waste is concerned I'd hardly worry about how to get rid of the final compost -- even if it went to the landfill it's way better than the rest of the stuff we throw out.
posted by loiseau at 6:26 PM on December 7, 2007

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