A banana circle grey water management system is one of the best examples of a closed loop permaculture design. Here’s how it works.
A banana circle consists of several key elements, all of which can be tweaked and adjusted.
- It has a compost pit where kitchen waste can be thrown.
- The compost acts as carbon, through which grey water from the kitchen and shower can flow through as it sinks down to the ground beneath.
- Directly around the compost pit are grasses and leafy plants who are water loving. Their roots keep the walls of the pit in place, and provide another layer of filtration.
- As the compost pit is dug, the soil is piled around the outside creating a raised ring. Here, banana plants are grown. Banana plants are voracious feeders (they need a lot of nutrients and water to be happy). The compost pit with its constant supply of kitchen & garden scraps, and grey water filtering down, supplies both in abundance.
- You can add more levels to the design, for example planting sweet potato or melons between the bananas, or vines that climb up the stems of the banana plants. You can grow papayas instead of bananas, or mix them up.
Installing our Banana Circle
In our case, I planted lemongrass around the inner circle, later adding some lovely comfrey and sorrel which provide an excellent chop and drop resource (comfrey speeds up composting). In the outer circle I planted two bananas (I’ll use their pups to slowly spread them out around the circle) and two papayas. Our grey water pipe is connected to the kitchen sink, the shower, and our composting toilet’s urine separator pipe (urine is actually rich in minerals & a great fertiliser). We dug a shallow trench and buried the pipe.
What I’d Change
We’ve had an issue twice in that time where the shower began to drain very slowly (both times after flood-proportion rains), but it took me a few minutes to push matter away from the drainage pipe entering the compost pit to restore a good drainage flow.
I would recommend digging a bigger hole than I did though – I made ours about 60cm deep and 1m wide, purely because the soil was hard and I was soft. I think we’ve gotten away with it since it’s just the two of us here, and Russ is often away in Cape Town for work. Had we been a bigger family, I’m sure it would have become a problem.
The only other issue we’ve experienced is winter frost damaging the banana & papaya plants. We lost one papaya, but the banana plants survived despite looking dead, and one has even put out a pup! If you can situate your circle somewhere it is protected from heavy winds and frosts, your bananas and papayas will likely be most thankful.
Overall, I love our banana circle grey water management system and it is a great success!