Steve Farmer wrote:How about throwing a few flushable chunks of charcoal into the toilet every x number of flushes? Would this save the need to open the IBC and add straw etc, or would it just end in  charcoal sludge similar to the problems of using sawdust?

Charcoal floats! You might have a problem getting it to flush. I really don't know what would happen as it's not something I've considered trying. It's possible to add it to the system, but personally I wouldn't rely on it as the only carbon component. It's not the natural habitat of worms and their associated ecosystem - that's the litter layer of the soil - so I think I would be very cautious about using it in concentration. Bottom line is that I try to imitate nature as much as possible. I think it's far less likely you'll go wrong doing that.

Just to update everyone on the system ...

It's now been approved for use by my local municipality under the provisions for 'septic tank with drainage'. (To alter legislation to give it specific approval would take far too long and the council wanted to start using the system right away.) Last summer myself and a Portuguese architect oversaw the first municipal installation of the system to replace a failed septic tank. There are more in the pipeline.

The design has been open-sourced and I've now created a website for it, including full construction details, maintenance, case studies and a forum where the community of users can ask questions and discuss problems.

Thank you Wendy for the work that you have given towards this project. It looks like a project that I will be doing on my farmstead.

I do have a question in regards to dealing with the government. What is the best way to approach this? Would working towards vermicompost or a modified septic tank approach?

Neil Stratton wrote:I do have a question in regards to dealing with the government. What is the best way to approach this? Would working towards vermicompost or a modified septic tank approach?

The Portuguese authorities I've dealt with are pretty pragmatic and open-minded. I have no idea how that all works in the 'States. I would guess a lot comes down to the individuals in your local municipality? You could certainly blind them with science by going armed with all the relevant research (I've linked some papers on the website}.

Wendy, I'm glad you're still here updating us. … ETA: And wow, your website www.vermicompostingtoilets.net is amazingly informative -- Thank you!

Our school in the Himalayas has dry composting toilets, but now that we have about 80 to 140 people living here most of the time, we are planning to install this kind of filter for the greywater before it goes to the canals along the trees. Until now, the greywater from the kitchen and from the bathing block go direct to little surface canals. The kitchen one, especially, tends to stink.

We don't have wood chips available, but all summer the local lumberyards happily give away wood shavings and sawdust. We've been trying to get sawdust for the toilets, but it tends to be mostly wood shavings and a few chunks, so I think we can use it. And I think you mentioned up-thread somewhere that it might be good to mix in a few autumn leaves (not enough to mat down) and sticks and bits, eg garden waste. Do you think that sounds good?

We had some compost worms in a big pile of drying cow manure last year -- I hope they haven't dried out or something, but I assume there are still some in there.

We got the pits dug and the stonemasonry done before winter set in, but we have to wait till March or April to finish them with the waterproof cement plaster. I hope it works!