Measuring Poop For A Better Sanitation Service


Hacking can make a huge difference in peoples’ lives. So when the Nottingham Hackerspace was challenged with optimizing Ugandan Toilets, they hopped on-board.

Back in January of this year [Nicola Greene] approached the hackerspace with this real-life design problem. She represents Water for People, with support from a UK-based Engineers Without Borders organization. Water for People is involved with improving access to sanitation in Uganda and many other third world countries — to make sure everyone has access to a safe and usable toilet. The cool thing with Water for People is they don’t just want to build an infrastructure for the people and run away, they want to bring together local entrepreneurs and the community to establish a system that will actually last.

So, what is the problem anyway? Well, since Uganda doesn’t have quite the same network of sanitation businesses as we might, it’s important for the new infrastructure to know a few things — in particular, how much do we poop? This question was summarized into a basic goal for the Nottingham Hackerspace:

To develop a low-cost (<$200) monitoring device to give an approximation of what volume of liquids — and in an ideal world, solids, is entering the latrine.

Before you click through, think about how you would solve this?

The system must be robust, excrement proof, operate without mains electricity, easy to make, and capable of dropping a log of data into a memory stick.

The team split off into three groups — one to develop an IR based sensor, one to develop a temperature sensor, and one to make a toilet (and some fake poop!). After an afternoon of hacking, the members regrouped to test their ideas. Both solutions ended up working!

Two members, [Matt] and [James], are continuing development of this project for initial testing in the UK, and later this year, in Uganda! If proven successful, it will go on to become part of an integral world-wide study of monitoring pit latrines by Water for People.

Well over 300 words… we sure can spend a lot of time on toilets.

17 thoughts on “Measuring Poop For A Better Sanitation Service

  1. A colander mounted inside a bucket – inside the toilet that rotates on a horizontal platform mounted to a set of scales, also has a small release pipe (aka electric valve) at the bottom of the bucket to release the pee.

    So you do your business in the colander, and you place a lid on the colander. The weight is given on the scale. You release the valve allowing the pee to drain from the bucket (as it has soaked through the holes in the colander), giving you the second weight. Then you just rotate the thing upside down and let the shit fall into the toilet and flush it away. every so often you can hose the “catcher” out.

    Materials: bucket, colander, scale, epoxy glue, small electric valve & battery, and some scraps of steel bar.

    1. You can’t rely on the users to cooperate. They will skip steps, they will do it incorrectly, they will forget, they will have dirty hands, they won’t want to touch the dirty device, they will lie. Measuring the toilet use without their participation is much harder, but much more valuable.

  2. Ugh! Just weigh in and out. Get to go on a normal can. Guesstimate ratio on the availability of beer and weather dryness. Since most of the rest of the world squats, it’s easy to separate #1 from #2 even for women. Just a little divide right in the middle, fore and aft. There is another project in Africa that does this. #2 goes to some soil composting I think. #1 goes straight down into a pit filled in with loose soil over which is the “bathroom”, after a few years they move it and start all over again. They plant a tree in the old place which takes root in an arid sun struck clime and becomes the central point of the village.

  3. Stick a capacitive sensor in your waste tank – basically just a couple of sheets of metal, painted (to reduce corosion) with wires running to either an microcontroller or an op amp. Go arduino for that hackaday feeling.

    Simple, effective and should be able to tell the difference between full and empty. You should also be able to do estimates of solid waste content with some calibration.

    Consider dumping the waste into methane digestors to provide gas for cooking.

    1. Just what I was thinking. All you need to do is add a receipt printer and you have an entry for the Sci Fi contest that hack a day is running. (Well I guess you need some input from multiple contributors.)

  4. Just count the number of people using the latrine. There are reams of data on how much people pee and poop from numerous medical studies. There is no need to actually measure the village output, use standards, pad capacity for both growth and normal fluctuations, and be done with it.

    Geesh, five minutes with a medical expert (or even a real sanitation engineer) would have saved weeks of fiddling around with a hackerspace that is clueless.

  5. “…and capable of dropping a log of data into a memory stick.”

    Sorry, I’m not retrieving the memory stick; that can be someone else’s job. (c:

    How are they planning to deploy these devices? Admittedly, I only browsed quickly through their blog, but I don’t remember seeing any mention of this. I hope they come up with an easily workable plan that doesn’t involve opening up existing septic tanks. I see from the picture that the tanks are fitted with a removable lid, but, IMHO, it’s one thing to open the service hatch to empty it, and quite another to open the lid and try to fit a device while hovering over a partially filled septic tank.

    Anyway, well done to the Engineers Without Borders for their work and for what they continue to do.

  6. Depends on what kind of toilet they use, on a standard north american one just drill a small hole exactly above the filled waterline in the crapper, when someone makes a deposit overflow is collected in a container, and according to that naked greek guy solids should displace more than liquids, combine this with a flush counter and you can make a simple calculation to figure out how much you have had deposited.

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