The successful installation of a vermicomposting flush toilet at Quinta do Vale in 2014 was the project which started the whole thing off. This was the initial modification of Anna Edey’s design by Wendy Howard which eventually led to the open sourcing of the design and the development of this website.
Wendy’s original blog posts from the time of the installation can be found here and here. There was also an article published in Permaculture Magazine, which is partially reproduced and updated here.
Quinta do Vale is an off-grid permaculture project of 2ha in the mountains of Central Portugal. It’s an evolving demonstration site for many aspects of sustainable living, with a particular emphasis on off-grid infrastructure. It’s run by Wendy Howard.
When I first started planning the infrastructure here, I intended to use Joe Jenkins‘ dry ‘humanure’ composting toilet system throughout. It’s simple, easy to construct and maintain, portable even, and doesn’t require separation of urine from faeces. And it’s an efficient thermophilic composting process with a well-balanced output. It’s no wonder Jenkins’ toilets have been dubbed ‘Loveable Loos’. What’s not to like?
Many people though dislike dry toilets. If there’s to be a mass movement towards better ways to deal with our sewerage, then this can’t be ignored.
In 2013, we were converting an old hen coop into an outhouse toilet. Coincidently, at the same time I came across Anna Edey’s experiments with vermicomposting flush toilets in Massachusetts two decades ago. It’s described on the website promoting her book. Edey’s website didn’t give full details, but there was enough information for me to work the rest out for myself. As it happened, the situation of the outhouse was ideal for installing a similar system, so that’s what I did.
The nature of the mountainous region where I live with its steep slopes (averaging 30-45°) and thin soils makes it a particularly challenging environment for conventional septic tanks which rely on soil biota to treat tank effluent. Slopes are too steep and soils too thin to fall within recommended ranges for successful treatment. It’s also common here for there to be almost no rain during the summer months and soils lacking in organic material soon bake dry. There is little evidence of soil life. As a result, most of the waterways of the region evidence septic tank pollution. In the absence of any other conventional solution for rural sewage treatment, I was keen to see how well a vermicomposting system would perform.
From a conventional flush toilet, flushings drain through a waste pipe into an insulated plastic container. The container holds a large quantity of worms who inhabit the surface layers of a mass of carbon-rich organic material (wood shavings, bracken, leaf litter, etc. topped with a starter layer of half-processed compost).
When the flushings enter the container, the solids remain on the surface to be processed by the worms and the liquids drain through the organic filter material and exit the container. They then pass through another waste pipe to a growing bed, also full of carbon-rich material, where they’re taken up by plants or further processed by soil bacteria.
I used a second-hand 1,000-litre plastic IBC to form the basis of the system. We made an access hatch by cutting half of the tank’s top out. It slots back into place neatly, held by the screw-top lid to the central opening (through which the waste pipe empties into the tank) and an aluminium bar which clips onto the frame each side. Once the tank was sited, we connected 110mm plastic waste pipe to the outlet and dug it into a trench leading to the growing bed.
The tank is sited immediately below the toilet in a dry-stone schist enclosure. As the walls were built, insulation was added to keep the worms within their optimum temperature range of 13-27°C, winter and summer. Closest to the tank, we used sheets of polystyrene insulation, and filled the gap between the insulation and the stone wall with Leca (lightweight expanded clay aggregate). A relatively lightweight galvanised corrugated metal hinged roof makes access to the tank simple. More polystyrene insulation was fixed to the underside of the roof and the top of the tank.
The growing bed, about 1.5m³ in volume, contains ½m depth of wood shavings, leaves, etc. to act as an organic sponge and carbon reserve. The vermifiltered water is piped into the bed and flows through a branched system of perforated 40mm waste pipes laid in the upper layers of organic material. The pipes were wrapped in horticultural fleece before covering with more organic material and then topsoil. This one bed has proved sufficient to deal with the comparatively small volume of liquid generated by the toilet (greywater goes elsewhere). The bed is unlined – there’s no possibility of contamination of groundwater or neighbouring properties. There has been no evidence of any seepage through the filter, even after large amounts of rain.
Once the water supply was connected to allow for flushing, the system was ready to go. The original plan was to start things off with worm-rich horse manure, but a cold wet February was the wrong time to find worms in the manure heaps. Instead I obtained a kilo of worms – about 5,000 Eisenia fetida or tigerworms – from ebay and added them to the tank along with some recent additions to the humanure compost heap and some kitchen scraps. We then started using the toilet. The green filter bed was backfilled with topsoil and planted with a lemon tree.
During the initial settling-in period, there was a slight smell from the container, but it disappeared within a week and the system has been working well for over 2 years now. It needs topping up with more organic material every 4-6 months and has dealt effortlessly with regular usage by between 1 and 6 people. The lemon tree showed signs of nitrogen deficiency by the summer of the second year (indicating the worm tank is working so well that almost no nutrient is escaping) and had to be fertilised.
I had a small incident in December 2016 when the tank started to fill with water. I unknowingly knocked the filter mesh out of place when scooping out some worms to start another tank going and some organic material got past it and blocked the outlet. I realised something was wrong when I could hear water falling on water in the tank after flushing. Fortunately some drainage was still happening so the worms were OK, if a little stressed. I cleared the blockage, resited the filter mesh, added some fresh organic material and all is well again.
The vermicomposting toilet system at Quinta do Vale can be viewed, along with other off-grid infrastructure and permaculture design implementations, by arrangement. For further details, see the project’s website.
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Did you vent the toilet drain pipe? We are building a bathroom, and were planning on building a composting toilet, so we didn’t install a toilet drain. It would be difficult to install a in wall vent when we install the toilet. I was wondering if it was even necessary with this type of system since there shouldn’t really be any back pressure.
Yes that’s right. It’s not vented because there’s no need. The drain pipe opens into the space above the organic material in the worm tank – air – so there’s nothing to produce back pressure. With a large enough diameter pipe (110mm) and the correct drain slope on the horizontal runs, I can’t envisage any situation where ventilation would be useful.
This is the second time I’ve tried to communicate with you here. I signed up as a member, but cannot post on the forums unless I buy a business account?
I made a post here, but it was under review before being shown to the public, however, I cannot find it now. Was it deleted?
My question is: Do you have a permit of some sort to have this vermicomposting toilet? The local government won’t allow me to build this unless I can show it has been approved somewhere else.
Can you provide documentation?
Thank you very kindly.
Greetings Wendy Howard,
I found my other posts. This page is confusing as to how to keep track of threads and, even though I’m registered, I cannot post on the forums without a business account?
Thank you very kindly for looking for the documentation. I am eager to get it. I will also try to contact Anna Edey.
I’m not sure why you’re having difficulty logging in to the forums. I checked the members and you’re listed. There is no business account option because this is not a business. The forums are free to use. I just checked the registration and login process by setting up a dummy account and then logged into it with no problem, so it all appears to be working as it should be. Were you using the orange login button on the Forum menu bar to log in? If so, I can only suggest registering again in case there was some glitch in the process. If you want to use the same username and email address again, let me know and I’ll delete your existing listing.
You posted comments to both the main Case Studies page and the Quinta do Vale case study, so perhaps that explains your difficulty finding your posts again? Your first post went through moderation, but all subsequent ones have gone straight through.
As I said, it may take some time to get any kind of confirmation out of my local municipality. The wheels of bureaucracy turn extremely slowly in Portugal. On top of that 90% of the municipality’s area of jurisdiction was devastated by wildfires last October, so their workload has more than doubled providing help to people who’ve lost homes and businesses and this currently takes priority over everything else. I’m supposed to have an appointment with one of the engineers this week about that, so I’ll slip in your request, but can’t promise anything. The vermicomposting system is permitted under provisions for “septic tank with drainage”, but is not explicitly referred to in the regulations. It takes years to change planning regulations here and the municipality wanted to be able to use this system immediately.
Thank you very kindly for your assistance.
The text concerning business account/free account is gone now, however, I still cannot post on the forums. I took a screen shot, however, I cannot paste it here.
I sent en email to Anna Edey at Solviva and am awaiting reply.
We are trying to build an off grid research farm, but are getting stonewalled by the local governments since the solutions we intend to employ for construction, water collection and water treatment are unknown to them — it’s as though they have never read anything about ancient or modern techniques that have not been placed in the so-called international residential code by corporate interest groups.
That is why I am seeking documents showing that vermicomposting has been approved by another local government — so that the local governments I’m dealing with can accept the practices as safe.
Thank you very kindly for your assistance.
I love this system. I installed one about 2 years ago and never had any drainage issues, smells or anything. Thank you so much for detailing and open sourcing this information! I built my bathroom up on posts to accommodate the IBC tote underneath. The drainage from the tote goes to a mulchbed where I have bananas growing. The bananas are doing so well that the mulch has been “eaten up” and the roots of the bananas have infiltrated the drainage pipe. Occasionally I hack back the roots and clear a new space, and add more mulch around the bananas. To keep the drainage free from the roots, I am planing on draining it into a box that sits over the mulch so that the roots can’t get to it.
Anyways, I would love to contribute to the forum, but I think there might have been a glitch when I registered. I didn’t receive the confirmation email to create a password in my inbox or spam folder. Any help with that would be appreciated! THANKS!