Greywater dispersal system

My first major post-permaculture design course project has been the construction of a greywater dispersal system.

But first, a bit of background info is needed.

When we moved into this property, 10 years ago, my aim was not only to become self-sufficient in food, water & fuelwood, but to prepare for the inevitable changes that energy decline is going to bring about.

One of the things that seemed dubious in the future was the provision of water. With a growing population and a warming climate it seemed likely that eventually, one day, water would not be piped to private properties as it is now. Either there wouldn’t be enough water or there wouldn’t be the energy to pump it. So flush toilets would become a thing of the past, hence the choice of a composting toilet.

That bit was relatively easy, although getting the permit through Council wasn’t (being a forward-thinking person in a backward-thinking municpality is never easy!). Composting toilets are EPA approved, so they couldn’t really refuse, and we got our toilet eventually.

The problem then became what to do with greywater. I originally conceived of storing it in a tank to use on the garden (although I didn’t know it then, and neither did the plumber, that it’s illegal to store greywater for longer than 24 hours).

What the plumber did know, and told me, was that because of the levels, a tank would have to be below ground. That meant energy to pump it up, so that was out.

We had planned to have a system of pools or a wetland at the rear of the property to take the water tank overflow so I figured maybe the greywater could be run into that as well. I’d already dug out a shallow natural watercourse from the tank overflow pipe to the pools (there’s a slight natural slope), so asked the plumber to put the greywater exit pipe next to the tank overflow pipe. However running greywater above ground like that wasn’t legal either, and the Council told me I’d have to install a reed bed system. I didn’t want the boxed-in type of system, where the reeds are confined, because I knew they’d eventually choke it up, so opted for a natural system where reeds and rushes would be planted around the outlet pipe and free to grow and spread where they pleased. There was so little greywater that it didn’t ever make it down to the pools anyway.

So that’s where things were when I started the permaculture design course. I’d been dissatisfied with the system for quite a while, but couldn’t see my way clear as to what to do about it. When we did greywater systems it became obvious that I was wasting that water growing reeds and rushes, when it could be used to grow more food.

Here’s what it looked like when I started:

The white pipe on the left with the cap on it and the hose sticking out, connects to all the downpipes from the roof and the pipe that runs into the water tank. When the tank is being filled the cap is put on the pipe and water backs up in all the downpipes until it reaches the level of the tank, so it runs into the tank. When the tank’s full it overflows into a nearby pipe (just visible at bottom left) which also runs into the reed bed system. In winter, when the tank’s full and the water’s not being used much for the garden, the cap is unscrewed and the flexible black pipe with the blue end, is poked into the main pipe and this takes the roof water straight to the pools (it became necessary to abandon the idea of a natural watercourse because too much water sank into the ground and didn’t make it to the pools). When full, the downpipes contain about 400 litres of water so the hose on the cap allows me to direct that water where I want it. (Taking off the cap when the downpipes are full is perilous—the rush of escaping water nearly knocks me over and erodes all before it!)

The white pipe on the right is the greywater exit pipe. The plants behind it are the remains of the reeds/water plants that were planted around it. Water used to run out of that pipe onto the ground amongst the reeds. I’ve removed most of the plants around it and inserted a slotted drainage pipe into it.

The slotted drainage pipe is about 10 m long and runs beside the stormwater pipe (which, of course, is not slotted). I’m hoping it will be long enough to cope with all the greywater, but if not, it can easily be extended. In this next picture, I’ve removed some of the reeds and covered the ground with wet newspaper. This is to prevent any seeds that were in the ground from germinating. I decided not to bury the greywater pipe completely because of the possibility of tree roots invading and blocking it.

Here I’ve covered the newspaper and the greywater pipe with mulched bracken. The only pipe visible is the stormwater pipe from the roof. At this point both pipes run alongside a path which is covered with grey gravel.

Here I’ve started to put in the first group of plants alongside the greywater pipe—3 feijoas. The 2 pipes, side by side can be seen, in the distance. I’ll eventually continue the mulched, planted area right to the end of the greywater pipe.

I’ve now put down more newspaper and bracken mulch and planted more fruit trees. There’s the 3 original feijoas, then 3 redcurrants, then 3 more feijoas and 3 more redcurrants (it’s going to be a fairly formal planting and will use up an excess of those two species, which I’d grown from seed). In between and slightly behind the line of trees, I’ve planted a dozen rhubarb seedlings. I haven’t managed to get rhubarb to grow successfully anywhere else and I’m hoping the nutrient-rich extra water will do the trick. They’re a bit further away from the greywater pipe but I expect they’ll eventually find the wet soil near the pipe if the water doesn’t manage to spread out to them.

In front of the stormwater pipe, at the edge of the path, I’ve planted some local natives, Mentha diemenica (native mint) and Chrysocephalum semipapposum (Clustered Everlasting), a clumping native daisy with silver-grey foliage and terminal clusters of yellow button-daisies. The mint will spread under and around the pipes and should love the wet soil. The daisy will provide some pretty spring colour and will also spread slightly. Both plants should eventually hide the stormwater pipe somewhat. There’s even a self-sown tomato in the front of the picture which is doing well.

To check whether the greywater was going to make it to the end of the pipe, I put on a full load of washing and stood and watched as the wash water pumped out. Yay! The greywater easily reached the end of the pipe (because it’s on a slope) and in fact, most of it probably ended up there, which caused me to worry that the plants closest to the outlet wouldn’t get enough water!  I could see, by lifting the pipe, that water was coming out of the slots all the way along, so things will probably be OK. A full load of washing is a lot more water than would come from the kitchen sink or a short shower and those smaller volumes of water should water the plants at the beginning of the system adequately. I’ll just have to wait and see how it goes, but in any case, I’m much happier to think that every drop of water that goes down any plughole in the house is now being put to use in growing more food.

Seeing as that self-sown tomato is doing so well, I’m even thinking ahead to next spring and wondering how a few cherry tomatoes might go, tucked in between the fruit trees and allowed to sprawl over the ground. Might mean taking more frequent and longer showers!

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One Response to “Greywater dispersal system”

  1. Permaculture reflections « Foodnstuff Says:

    […] That I was simply wasting good greywater by running it on the ground and using reeds and rushes to absorb it, when I could have been using it to grow more food. […]

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