Monday, October 05, 2009

Dealing with domestic waste water :
Our new horizontal plant filter is now up and running, dealing with all our grey water (that means everything but toilet water). Here in the French countryside it’s normal to have one’s own sewage system. The, almost universal, septic tank is basically a settling tank containing both floating and sinking solid waste, while the water in the middle passes on to a sand filter. About every four years, a brave man with a tanker, a pipe and a strong pair of rubber gloves, arrives to pump the septic tank empty and take the waste away to a municipal sewage system. So this “autonomous” system doesn’t actually deal with the waste completely. And I believe that the sand filter should be changed every 15 years or so.

Our house already has a functioning septic tank, newly fitted not too long before we moved in, so why the change? Unfortunately, it’s of the smallest size possible, already has our holiday cottage connected, and is just too small to accommodate the new gite, a barn that we’re converting/renovating. It would be expensive, disruptive, and seem a touch wasteful, to remove the current tank to install a larger one and the lie of the land is such that we’d struggle to find the space to install a new septic tank for the new gite, at the very least requiring an electrical pump. (I really don’t want a pump in the system as pumps break down and need repairing and I really don’t fancy having to repair a pump covered in shit!)

Cue brilliant brainwave from Gabrielle: we disconnect our current house and provide a new system for that on the other side of the building, where we have both the necessary space and gradient. We would then connect the new holiday cottage to the existing gite … but. Ahhh, we’re told that the standards have become more stringent since the septic tank was installed and is too small for two buildings. We asked the authorities to consider that, even if this wasn’t up to current regulations, if we disconnected our house in constant occupation and replaced that with a seasonal gite, occupied about half the year, the septic tank would actually be working less. Never mind what negative comments you might’ve heard about French bureaucracy, they kindly accepted our logic and said “yes”.

We could have paid for a new septic tank and sand filter leech field but we thought we could do better. In permaculture, we try to analyse inputs and outputs of our smallholding in order to reduce inputs from outside and try to use our outputs onsite. It's also about being responsible for the waste we produce. Human waste and wastewater from the house can be used to grow plants. It’s a matter of scale. The sewage from a whole town gathered together in one place becomes a pollutant. Sewage from just one household, treated on site, is certainly not a pollutant and could even be useful.

Our new system consists of a horizontal plant filter, 2 metres by 4, with the cleaned water going into a wildlife pond. Our rainwater passes through a valve, diverting it into our storage tanks until full, then also flowing into our pond. The pond is conveniently placed to use it to fill watering cans for the vegetable patch and polytunnel. At the moment, our toilet is still connected to the original septic tank but I will soon be installing a twin vault dry composting toilet with urine separation.

Horizontal plant filter, study and installation: Éleonore and Christophe from Aquatiris
Dry toilet design and components: Andy Warren of NATSOL.