Daily Audio - AKG Sustainable Living Project episode #4 - Rainwater Harvesting

Wednesday, 21 April 2010

The AKG Sustainable Living Project podcast episode #4 transcript- Rain Water Harvesting

Here is the transcript for our latest episode for The Alternative Kitchen Garden podcast;

"Hello this is Jacqui and Robb from the sustainable living project. First we’d like to thank Emma for allowing us to contribute to her wonderful podcast and for sending us her book as winners in her birthday plant competition. We are thoroughly enjoying the book, “The Alternative Kitchen Garden- an A to Z”, and highly recommend it to all our readers and listeners. And now on to our contribution for this month.

In our last post we mentioned our plan to create a rainwater harvesting and management system on our site. Why would we do this? The public water system is a surprisingly inexpensive way to get your water when the supply is plentiful and local. One of my instructors on my masters course was adamant that investing money into rainwater harvesting was pointless from an economic perspective as it would never pay itself back, and perhaps in the mountains of west central Wales she is right, I’ve never seen a rainier place.  But this fails to address several issues with public water systems; they use large amounts of fossil fuel generated electricity to pump, purify and process water. They leak vast quantities of this energy rich water. The water they deliver has had a chemical cocktail of treatments added to it to make it “safe” for human consumption, more on that in a moment. In the US, the drinking water in many locations contains rocket fuel from the defense industry, pesticides from industrial agriculture, e coli from concentrated livestock feeding operations, heavy metals from sloppy mining practice, and in may cases is too acid to be safe for long term exposure. And of course there are the obvious inefficiencies of mixing sewage with treated drinking water and then having to clean the whole mess up again. In addition, depletion of ancient aquifers is a looming problem, threatening our future food and energy supplies.

As to chlorine, it is a chemical designed to be antithetical to life. It is used in water for one thing, whether in swimming pools or drinking water, to kill micro-organisms. Perhaps it is the best choice for large municipal water systems but there are many indications that consuming chlorine and its by products, notably trihalomethane, is not good for your immune system.  The basis of healthy soil and thus healthy plants is a thriving, diverse ecosystem of micro-organisms. Thus, chlorine is designed to eradicate the very foundations of healthy soil. Rainwater is better for your plants as it is naturally soft and contains no chlorine. Rainwater can be purified for human consumption without chlorine.

So we have decided to harvest rainwater. Rainfall in Hickory averages around 4 inches per month. However, prior to the current El Nino cycle there were extended drought conditions. Water levels in the reservoirs in the SE fell to historically low levels causing jurisdiction and ownership disputes, threatened hydropower production, and brought on water usage restrictions.

Our property collection area, including the structures, is approximately 14,520 square feet. Assuming normal rainfall patterns return, we can expect 250 to 400 thousand gallons falling on our property per year. A typical household in Hickory NC uses 68,400 gallons per year, not including lawn watering. I’ve seen estimates that 10,000 feet of lawn will require an additional 312,000 gallons per year.

The large amounts of food and biomass we plan to grow would normally be expected to need more than the average lawn for irrigation but we believe that by using sensible permaculture techniques to increase the moisture retaining properties of the soil we can use less. Our demand should easily fall within the supply.

The key is to keep the rainwater from running off the property too quickly. Storage is to be accomplished in three ways: tanks to store clean water for household and garden use fed by rooftop collection, small ponds and reed beds to treat grey water and collect the overflow from the roof, and in ground storage via swales and raised beds with deep, rich soil. A swale is a ditch dug on a contour designed to interrupt run-off and allow water to slowly sink into the soil.

Instead of a single permaculture tip today we’ve got 8 principles of rainwater harvesting from an interview on Sustainable World radio with Brad Lancaster author “Rainwater Harvesting for Dry Climates”. You can find this interview at sustainableworldradio.com in the podcast archive. You’ll probably recognize the permaculture influence in these principles, the book is recommended by many permaculture practitioners.

1. Long thoughtful observation of how water behaves on site.

2. Start at the top of watershed. Our property has a slope to it, so we will need to address water flow from the top of the roof to the bottom of the property.

3. Start small and simple. As the house currently has an asphalt tile roof, we will start by installing water butts on our carport which has a tin roof.

4. Slow it, spread it, sink it. We will be installing swales and terraces on the property to reduce run-off, and to increase absorption and storage.

5. Always plan for overflow as a resource.

6. Maximise living and organic groundcover, no bare earth, no standing water (mosquitoes need 3 days of standing water to breed)

7. Maximise efficiency by stacking functions, for instance: use tanks as thermal mass and use berms on the down side of sales as high and dry paths; also, raise lots of moisture rich plants to cool the property in the summer.

8. Long thoughtful observation. Get the feedback; what works and what doesn’t.

And that’s it for this episode. Thanks for listening and remember you can visit us at sustliving.blogspot.com. We’ll leave you with another take on water, slightly edited for brevity, from Sandra Postel, Post Carbon Institute Fellow,

'I think with water there is certainly not a facing of reality yet. It is a major issue that we have to deal with. There is so much we could do with the water that we have to meet our needs in a more efficient and productive way. It is very easy to see how we could save 25% of our water use in most situations if we put our mind to it and planned for that. Each of us has a water footprint, water is in everything we use everyday, embedded water. To the extent we use less paper or buy fewer clothes, and recycle those things when we are through with them, to the extent we move our diets down the food chain, consume less red meat, we shrink our water footprint. Which means we are leaving more water for other people and other species. But only if we get real about the issue and proactive about the solutions.'

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