Using permaculture ethics & design principles to transform an old energy guzzling bungalow into a showcase of sustainable design. It's about energy cycling, building community, self-reliance,creatively using & reusing materials... all without spending heaps of money.

Tuesday, June 5, 2012

Drinking unfiltered rainwater

Principle 3: Obtain a yield

We collect and use all rainwater off the roof for drinking, washing and irrigation with no problems. Our house uses a pump to create water pressure, while we irrigate with gravity feed using 19mm (3/4 inch) hoses; which is quite slow but allow me to weed at the same time. We prefer to drink and wash with pure rainwater rather than contaminated mains water, which according to our water supplier Goulburn Valley Water, contains chlorine / fluoride / aluminium sulphate and flocculant polmer which is used to 'clean' the water. The water then goes through km's of old metal and plastic pipes before coming out your tap. Why go to all that effort and expense to clean and transport water when you can catch it clean from the sky right where you use it?
I calculated the surface area of our roof recently so I could figure out how much water we were collecting. The total collection area is approximately 176m sq, with about 97m sq going directly to our main tank (23,000lt) 66m sq going to our reserve tank (8000lt) - which overflow to each other - and another 13m sq going to a small 200lt drum at ground level. We have 163m sq collection area for our main tanks, so we get 163 litres of water going into them for every mm of rain that falls on our roof (not including evaporation). With an average rainfall of 597.9mm per year we can expect to collect nearly 100,000lt per year (in a perfect world). Problem is, sometimes it rains when the tanks are already full. In fact in one 24 hour stretch this February we got 152mm of rain, nearly 25,000lt.
Collecting and using water on site helps to rehydrate the soil and recharge aquifers, while reducing runoff during extreme rain events. This is particularly effective in combination with earthworks, like the infiltration basins that we have set up around our garden beds, that hold water until they fill up, helping irrigate our plants.
Our property is connected to mains water, but mains water is only used as a back-up for irrigation purposes. We used mains water for the first time since we moved into the house for about a month over January - February when the water tanks were getting low, which causes low flow rates with our gravity fed hoses. We used about 10,000lt for irrigating @ a cost of A$9.36, while the water service fee was A$47.99. While I enjoyed the 'power' of using pressurised mains water, I didn't manage to do the weeding while I watered because it was so quick and intense. I've considered getting the mains water disconnected, but think that I'd be up for a fight, and it's a handy back-up.

Principle 4: Apply self regulation and accept feedback

Cheap plastic gutter guard proved to be more of a liability than an asset, blocking the gutters with debris
I probably got onto this job a bit late, as Autumn has well and truly set in, the leaf fall is a timely reminder. We haven't noticed the water becoming dirty or tasting bad, but I had noticed the gutters overflowing during heavy rainfalls and the plastic 'guards' that I installed falling out. Cheap plastic guards are a complete waste of time, so I decided to install heavy duty metal gutter guards to reduce maintenance and possibly improve water quality.
People may find the idea of drinking unfiltered rainwater a little hard to swallow, but a study of 300 households in Adelaide "showed that people who drank unfiltered rainwater displayed no measurable increase in illness compared to those whose rainwater was filtered". I've been drinking unfiltered rainwater for over seven years straight and have had no problems. I will not drink mains or bottled water unless there is no other choice -  I think processed water taste awful.

Heavy duty mesh gutter guard was installed and should reduce ongoing maintenance and help keep the water clean.

Water collected here runs into the smaller 8000lt tank, we've cut into the side of the gutter to maximise the height water enters the tank, which is taller than the gutter.
The quality of rainwater is ensured by a natural treatment chain in the tank that reduces the presence of bacterial and metal contaminants. Bacteria, organics and chemicals form flocs that become biofilms on surfaces or settle to the bottom of the tanks to the sludge. The processes of flocculation, settlement and biofilms in tanks act to improve the quality of rainwater. The majority of bacteria in rainwater tanks are harmless and from the environment.  -  Dr Peter Coombes (see report for more)
As our understanding of beneficial bacteria in our digestive system grows we have been feeling more and more confident about eating or drinking foods that may contain 'bad' bacteria. The idea being, feed the goodies, to fight the baddies. The thought of using antibiotics really frighten us, and we would only consider it in an extreme circumstance - why wipe out all that good bacteria if you don't need to? It's okay to let your body get sick sometimes, it'll figure out what to do, and it will strengthen your immune system in the process. We've been getting into a wide variety of fermented foods, to make our bodies more resiliant, but that's another story...

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