To help transition Japan to a peace promoting post-carbon country while enjoying every step of the process.
僕のビジョンは、祖国日本で、平和文化を育みポストカーボン(Post-Carbon) 社会を促進してゆく事です。

Saturday, July 3, 2010

Kitchen Greywater System



How can we utilize water from our sinks after washing dishes and hands?
How can we save energy from our complicated water systems that send our used water to faraway facilities that clean it then send it back to us?


Recently, we spent a few days upgrading our outdoor kitchen greywater system. For a while the water from our kitchen sinks were soaking a slope of herbs and flowers in that area. The new and improved system has a much larger capacity, and can be directed to water different plantings.

The beginning (kitchen sink)
The kitchen sink drains into one of 4 pipes. Depending on where we want to water, we can manually switch the pipe/area. Super simple design so anybody can figure out what is going on.

We dug a bunch of trenches to install a series of ABS pipes (black) that transport the water via gravity to a series of mulch basins (holes filled with coarse woodchips) in between perennial plantings. You can see the kitchen sink at the top in the picture above. The three pipes on the top slope lead to 3 different areas each with a few mulch basins.

Interns cutting, placing, and assembling pipes.

The flow splitters need to be level in order to have equal distribution of water to the two downhill pipes. Sand and/or gravel are helpful for leveling things, just like building a foundation. A hole was drilled at the top of the splitter then corked. This way if food gets stuck in the splitter, we can easily unclog it. Flow splitters are a specialty part that you can get from Oasis Design

Tatton deep in thought.
How is this pipe a metaphor for life?

This is the end of the pipe. The water drops out of the pipe onto the mulch. A shield keeps rodents from getting to little pieces of food that flow out. Having the pipe higher than the mulch prevents clogging of the pipe. A stone cap is put on as a rodent barrier and to make it look nice.

Before burying the pipes, we check the water flow rate with a jar and stopwatch to make final adjustments. This part of the system split the water into 4 mulch basins. We timed how long a mason jar would fill up at each outlet and adjusted the pipes as needed. I think there were two outlets that filled the jar in 7 seconds and one that filled in about 13 seconds. That's almost twice as much volume per second. Always good to check your system, before covering it.

Caitlin's notes on the kitchen gray water system.

SUMMARY: Basically, pipes from the sink lead to downhill holes filled with stuff where the water flows into and seeps into the soil. The flow of the water from the sink -> filter (plastic colander with straw in it, cheap and simple) -> pipe -> splitter -> pipe -> flows onto mulch.

This way greywater is transformed from waste into a resource. And we save a lot of energy, which is at at the heart of much of our problems......and solutions. Fossil fuels, nuclear, etc. What we implemented here makes sense for our site, and each site will have different opportunities and challenges. This won't work in non-percolating soils as is. But with permaculture lenses a effective solution can be found.

A few final notes on the beauty of this system. Anybody can implement this system (few simple parts), uses no energy once setup (lots of work to dig trenches and making plastic requires energy), easy for people to understand the system which is great for teaching, fixing, and expanding, and its cheap. Plus it fulfills a need (watering perennial plantings) with a waste product (greywater). There are other things I could add but I need to sleep.

* We use biodegradable (liquid soaps and detergent). In alkaline soils you'll need sodium free soap.

Architect Friedensreich Regentag Dunkelbunt Hundertwasser's tree tenants are pretty inspirational for urban settings. Art Ludwig (Oasis Design) authored a few essential books on designing greywater systems, and Brad Lancaster's Rainwater Harvesting for Drylands. I also remember attending a talk by two girls who were the Gray Water Guerrillas. They were doing good work, check them out at Related topics/systems are black water systems and rainwater harvesting but I will get to that later. As always, there are tons of information on the internet.

in Costa Rica and Nicaragua, most rural homes that I saw had a short pipe from the sink that stuck right out of the wall, where the water would fall into a shallow ditch dug into the dirt, that lead to a patch of banana plants. Now that is a simple system! And, the bananas thrive on that greywater. I'll keep an eye out for a picture.

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