Composting Toilets

Hi. I think this is a Bog Blog! I live in an ecologically friendly house. It took a year to research and a year to build. Adobe brick, wool insulation, wired to prevent electromagnetic fields, passive solar heating, earth floor (in one room), quantum water heater, no chemical products (polyurethanes, glues, plastic veneers, etc.) and no treated building products (i.e. no imported gib, no treated timber). Anyway, I installed a composting toilet.

I am aware that there are now numerous fancy composting toilets or toilets that treat waste in a variety of ecologically safe ways. Mine is a very basic 'Toa Throne'. At the time (1994) it was one of only a couple available in NZ. The Toa Throne treats human waste by separating the liquid (okay urine) and off to a soak pit or, in our case, two open air ponds that take all our grey water (no septic tank). The solid waste (yes, the brown stuff) goes into a tank below the house. An exhaust fan sucks warm air from inside the house (behind our fridge and freezer) through a series of angled steps on which the waste falls down. This warm air and some internal heating rods provide the bacteria with much needed heat and oxygen to break down the waste. Watch dog poo on the lawn? It isn't there for long (and not because the neighbours Beagle ate it) but because the sun and the air dehydrate it and reduce it to powder. Same principle going on under my house, 24 x 7. So most of solid waste is water, evaporated and blown out an exhaust pipe over the roof. Because it is aerobic and not anaerobic like your disgusting septic tank (even the name 'septic' makes me reach) there is no pungent smell like normal sewerage. In addition, because most of the waste evaporates, there is really very little left behind to dig out of the toilet.

Maintenance: You do need to start your toilet off with some potting mix, sawdust (non treated) mix. This supplies the all important bacteria. Then you must 'feed' your toilet all the vegetable scraps you can. The toilet needs roughage to keep it aerated. So if you don’t eat vegetables, start! It will make you and your toilet happy! I dig mine out about once every few years via a nifty trap door. Only a few bucket loads though; not a lot. It looks like potting mix with (sometimes) a bit of brown paper. Hint: Don’t recycle the brown paper, okay? Oh, and if you find a kids toy (as I did) just bin it. I don’t think Junior sucking on his long lost Pooh Bear would be a good look. (Our bathroom would draw strange looks from visitors as we had a lock on the outside of the bathroom door for a few years.)

Things to look out for:

1. Obviously don’ let your kids throw stuff down there, yuck.
2. Women cannot throw their sanitray pads down there. Bactria don't eat those so well.
3. Keep feeding it. I underestimated how happy my toilet likes to be fed, a guest spent a week pissing down the wrong hole and it STOPPED composting. ($240 to get it pumped out.) This will happen if guests piss down the big hole and don’t use the liquid drain at the front. You have to discuss the toilet with guests, especially the men. Hey, it breaks the ice. Hint for Men: Pissing from the side makes an easier target. Women don't have to worry sitting down.
4. Keep the tank warm by either having it in the basement or wrapped in insulation if exposed outside. Internal heating rods are essential in colder climates like Wellington.
5. Make sure you leave plenty of room to swing a shovel when digging it out.
6. Power cuts can cause a faint ‘aroma’ to emanate from the bathroom. So use incense or glad wrap for more sensitive olfactory glands.

The great thing about composting toilets:

• They don’t smell.
• They don’t use any water. Up to 60% of good clean household water is flushed; just plain stupid, especially if you're on tank water. We live rurally and only had to install one 12,000 litre water tank for a family of four. Big saving.
• You get great compost for the garden (not much though).
• No arguments of the toilet seat lid up or down anymore. It must ALWAYS be down.
• It shows your sons friends you really are a lunatic hippy leftover from the 1960’s. Cost/benefit: Cost of toilet then (1994): $2,500 Installation $1,500 Saving on septic system $10,000 Saving on extra water storage $3,000 Look my mother's face? Priceless Net cost/(benefit) ($9,000)

Footnote: There are some fantastic toilets that treat the waste using UV light and/or spin the water out, etc. I don’t know a lot about them except that they are quite a bit more expensive.

Submitted by kimforbs on 19 June 2009 12:00:13

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