Oh, poo!

Over the past few days, a link to an article on the Guardian website has been doing the rounds on Facebook (at least in the circles I mix in, which are mainly related to sustainability). It’s entitled Why the modern bathroom is a wasteful, unhealthy design and explains why we might not want to keep our toothbrush next to our toilet and why it’s such an environmental issue to mix the water we wash our hands in with the waste we flush down the toilet.

Basically, the issue with water disposal is that grey water (from washing) can safely be used to irrigate the land, whilst black water (from the toilet) needs to be processed to make it safe. By mixing the two together, we end up with a lot more highly contaminated water that has to be processed in some way. According to the Guardian:

Over 10bn litres of sewage are produced every day in England and Wales. It takes approximately 6.34 GW hours of energy to treat this volume of sewage, almost 1% of the average daily electricity consumption of England and Wales.

I don’t know what the figures would be if we separated the two sorts of water, but I know they would be significantly lower. The real issue in my mind, however, is that we see everything that goes down the drain as a problem – all waste water is pollution in the current paradigm. What we need to do is realise that, in fact, all waste water is a resource… faeces and urine contain valuable nutrients, and water itself is an increasingly rare commodity globally.

And if we are thinking about fertility, The nitrogen fertiliser industry is big business, closely tied in with fossil fuels… according to the International Plant Nutrition Index:

All N fertilizer begins with a source of hydrogen gas and atmospheric N that are reacted to form ammonia. The most-used source of hydrogen is natural gas (methane). Other sources of hydrogen, such as coal, are used in some regions. After hydrogen and N are combined under conditions of high temperature and pressure to form ammonia, many other important N-containing fertilizers can then be made. Urea is the most common N fertilizer, but there are many excellent N fertilizers that can be made from ammonia. For example, some ammonia is oxidized to make nitrate fertilizer. This same conversion of ammonia to nitrate takes place in agricultural soils through the microbial process of nitrification.

Because the production of hydrogen gas required for the synthesis of ammonia largely comes from natural gas, the price of this primary feedstock is the major factor in the cost of ammonia production. Ammonia factories sometimes close or open in various parts of the world in response to fluctuating gas prices. Higher energy costs always translate into higher prices for all N fertilizers. (IPNI)

The classic image of a compost toilet

The classic image of a compost toilet

So, we flush great fertiliser away down the toilet (remember a key function of urine is to expel excess nitrogen from our bodies), pay for that to be treated to make it safe and then pay even more to extract nitrogen from the atmosphere to apply to the land to grow crops. Somehow, this just doesn’t seem sensible. Why not turn the waste into a useful resource and avoid a whole bunch of pollution?

I know that most people are squeamish about composting toilets and they are currently not readily available for use in ‘normal’ houses, but technology is changing. Soon, you won’t have to deal with the waste yourself if you want to avoid the standard flush toilet, and you wont have to have a compost loo in the garden either. Take a look at Toilet Revolution if you want to see a whole range of options suitable for real homes.


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  1. Woohoo, I’m delighted I don’t have to visit the garden if I feel the need to go. It can get quite nippy in Winter. But it is good that there are so many options available to sustain one of our most precious commodities- water, and can at the same time furnish our gardens with all the nitrogen and compost it needs.
    xxx Huge Hugs xxx

    • We’d all get used to it if these things were standard. Here in Wales water isn’t generally short, but we can always do with saving energy!
      xxx hugs xxx

  2. For the first 10 years of my life I had no idea what a bathroom was, we had an outside loo and a tin bath, I’ve never really been comfortable with bathrooms and I’d be happy to try a composting loo, providing there’s no methane build up!

  3. My father was ahead of his time, and installed a composting toilet in one of our bathrooms back in the early 80s. It was a monstrous white throne which you reached up a couple of steps to accommodate the composting chamber underneath. You had to feed it sawdust every so often to keep the mix dry enough, and every month or so you removed a tray from the bottom and took it out to the garden where it was eagerly received by the plants. It was a little intimidating, to say the least, and the way the two panels in the bottom of the bowl snapped apart when you sat down was also slightly scary, but it did actually do the job!

  4. Grey water I’ve heard of, but composting toilets? Those are new to me. I was always under the impression that human waste wasn’t good for gardening. I guess I was misinformed.

    When I moved here to New Mexico, USA… I thought there would be grey water tanks everywhere because it’s an area that’s prone to drought, but whenever I asked anyone about it, they looked at me like I had three heads. Seriously, it’d a foreign concept to them. Luckily, I’m not the only green person around here and they are growing in popularity.

    • Hunamure, as it is known, is fantastic for plants and perfectly safe if properly composted… see what Dave (Cambridge Aromatherapy) has written below. It’s an important component of many agricultural systems around the world.
      Strange how such a dry area as NM would not be using every bit of water to the max…

      • I know, right? It was absolutely amazing to me that there weren’t grey water tanks everywhere! Oh well, people are being educated now and they are growing in popularity. The city, alas, as very strict regulations about them…

  5. For the last two weeks, four members of our household–Percy, Fox, Blueberry, and Muffin–have been using a version of a composting toilet. Here’s how it works.

    1. The cats put their poo in conventional litterboxes, filled with classic Fuller’s earth clay kitty litter. (I know, I know … we tried everything else, but They had OPINIONS.)
    2. We scoop it out (the goal, at least, is daily), and I carry it out back to the kitty clod composter, which is:
    3. a five-gallon bucket, with about 10 cm of sticks piled loosely in the bottom to provide air and drainage space. Into it go successive layers of poo and fallen leaves (oak, hickory, and sweet gum, mostly). I cover it, loosely, with an old kitty-litter bag.
    4. Female black soldier flies (Hermetia illucens) lay eggs in it; they hatch into voracious grubs. That is the unlooked-for secret ingredient. I am not always grateful to live in the southeastern US, but in this, I am.
    5. The larvae party on, reducing what I expected might be a several-months-to-years-long composting operation to just weeks.
    6, I haven’t arrived yet at the “what to do with the product” step. Concerns about Toxoplasma gondii seem a bit pumped-up to me, yet I want to respect them. The most frequent advice comes down to “wait three years to use it; that should neutralize any harmful microbes.” But I can’t find the research to support that. So that’s still open, but I reason that my hyper-local processing solution is better than sending the poo to the landfill, and as good as flushing it down the toilet (= sending it to the sewage treatment plant, which explicitly says it doesn’t want the clay that clings so closely nor potential parasites). If I were a better amateur scientist, I suppose I’d get the cats and their compost tested for Toxoplasma gondii … are there grants for that? (grin)

    • Great idea. I think as long as you bury your compost you should be ok… we compost dog waste and then when I dig my bean trench in early summer it goes in the bottom and gets covered up with 12 inches of soil. The runner beans certainly seem to like it.

      • Hum … the cautious might try running it through another cycle with a green manure crop. Like you I might go straight for the beans!

  6. My understanding with composted human faeces is that the level of pathogens in the final product is lower than the background level in the soil in most gardens/allotments.

    If designing our sewerage system from scratch, perhaps we would have separate pipes for black and grey waste, enabling the poo and wee to be treated as a resource. Doing this on a smaller home scale is not too difficult and I hope that before too much longer we will be able to have a composting loo at our allotment site and possible one at home too.

    I wonder if this is being cynical but I wonder if the main reason this resource is not being fully utilised is that it would eat into the profits of the oil companies?


    • Like Maya (below) I don’t see why we aren’t using it for fuel too… I guess the argument is the same as for fertilisers… all sorts of vested interests whose focus is profit not optimum use of resources.

  7. I recently bought a very old gardening book which referred to ” night soil” as a fertiliser. I have been using a compostable cat litter for some time now because I just could not keep putting bags and bags of used litter in the dustbin knowing that it was going to landfill.
    I was not aware that I had to wait 3 years to use it though.
    I am really interested in these compostable toilets, but I don’t imagine that South West Water would reduce my water rates if I had one!

    • As mentioned above, I think if you bury the waste, there shouldn’t be a problem if it’s well rotted. Obviously, I don’t put dog waste compost on my lettuces, but I’m happy for the roots of my beans and squashes to grow in it!

  8. Seriously considering getting one.. as we’re refurbing the bathroom anyway (though we have been doing for 18 months, and it doesn’t have running water in there yet), but I haven’t been able to find a suitable composting toilet. Can’t dig through the floor as its solid concrete, can’t go too far up as the ceiling is really low.. don’t have tonnes of room to compost outside.. modern houses conspire against such adjustments!

    • There do seem to be quite a few options now. We have quite a small bathroom too, but I’m hoping we might be able to fit one in somehow. I’d be really interested to know what you go for in the end if you do find something suitable.

  9. I am thinking about a composting loo…our local council are pretty anti-composting loos. No idea why as it’s not like any of them even come out this far into the sticks to check and all! 😉

  10. I missed this in the Guardian, but glad to read it here. I’ve used compost toilets on holidays quite a few times and they are great. Our local council (Rushcliffe near Notts) has installed them in their biggest park – they use the compost everywhere except on the food they grow there. It would be really cool to have one in the house.

    • Oh dear, somehow your comment got put in the spam folder! It’s great to hear about local authorities actually thinking about waste disposal like this… and using the product too.

  11. Maya Panika

     /  July 19, 2014

    We should be using sewage to create gas. Anaerobic digestion for methane, then re-composting the remaining solids aerobically. The heat generated from this two-stage process decimates all pathogens so the resulting compost can be safely used as a fertiliser, plus we get lots of usable gas. Why we are not doing this simple thing instead of ludicrous fracking I do not know; I suspect there is no money in it.


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