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26 November, 2007

Sterilising My Drinking Water The Easy Way

One of the many things about living out here in the bush with which I am unfamiliar, is the way water is collected and treated. My new house has three separate water collection systems. One is a ginormous plastic tank which collects the run-off from the house and shed roofs. The next is a small pond (or 'dam' as we call them here) that collects water that runs off the ground. The third is a pair of large plastic tanks which constitute a waste treatment plant for sewerage and other domestic waste water. The waste water plant generates relatively clean water which it then pumps out into a garden sprinkling system. The dam water is untreated and also has a pump, which we can use as required for garden watering or whatever. Water from the ginormous plastic tank that catches rainwater from the roofs, is pumped up to the house to provide our domestic supply.

The dam water and the treated waste water don't bother me. We only use them on the garden (or will, once we have a garden). It's this rainwater/drinking water system that bothers me. This water comes off the roofs straight into the tank where it sits for very long periods before being pumped into the house. The tank is closed (apart from two fat overflow pipes with a mesh over their ends) but the water that flows into it comes from the roofs and gutters. Apart from whatever airborne dust, smoke, pollen, and other organic matter landing on the roofs, there must inevitably be bird droppings and dead insects falling onto them all the time. Surely this means the water can't be quite sterile and must have quite a lot of stuff living in it?

It's not such a big deal because Wifie and I never drink unfiltered tap water anyway and any other water we consume in our food is always put through some kind of cooking process that would sterilise it. Yet it is just a little bit unsettling that the water we consume has been used to wash a roof with and has then sat in a big tank in the hot sun for weeks or months before we get round to pumping it into the house! Also, the fact that more and more people around the world are drinking re-cycled rainwater from just this kind of system and no-one is jumping up and down and saying what a health hazard it is, is actually quite reassuring.

Yet I have been wondering what to do to remove any risk whatsoever. And I think I have the answer: make rainwater tanks out of clear plastic.

I came across this idea in August 2000 when New Scientist reported on an Oxfam meeting that discussed the use of solar disinfection to combat a shortage of chemical disinfectants in Assam, India. (Issue 2253, New Scientist magazine, 26 August 2000, page 14. You may need a New Scientist subscription to read this online. Otherwise, your library probably has it.) A team of Swiss researchers in Duebendorf has show that filling a plastic bottle with water and leaving it in the sun can effectively disinfect it in as little as one hour. Martin Wegelin, who headed the Swiss research team, says that if you paint half the plastic bottle black and stand it on corrugated iron, it will heat up much faster and cut the time needed for thorough disinfection. The combination of heat (the water temperature goes above 50 degrees C) and ultraviolet radiation kills most micro-organisms, including 99.9 per cent of Escherichia coli, Vibrio cholerae (which causes cholera), and the parasite Cryptosporidium (which causes severe diarrhoea). This last is particularly interesting to me since I remember an outbreak of Cryptosporidium and that other popular faeces-borne parasite Giardia intestinalis that hit the water treatment plants in Sydney one year when I was living there and meant that we all had to boil our tap-water before using it for several weeks until they got the outbreak under control.

So, if it works for a couple of litres in an old Coke bottle, maybe it also works for five thousand litres in a clear plastic rainwater tank. If no-one has done the science yet, remember you heard it here first and don't forget to add my name to the patent, please.

25 November, 2007

Change Of Life

So, here I am in my new home in the country – or the bush, as we learn to call it here. My life is in flux. For the first time, Wifie and I have moved away from the cities we have always been forced to live near and have taken up residence far, far from the madding crowd. So far, in fact, that we don't have mains water, or sewerage, or even a telephone line. The postie drops our mail half a kilometre away at the bottom of our 'drive' (a dirt track that is all but impassable in the wet). If it wasn't for that lonely pair of wires bringing electricity up here, we might be living a very much more primitive life. The nearest shop is twelve kilometres away, the nearest small town, twenty.

We live at the top of a thousand-metre-high hill and the forested valleys and hills of Queensland's Granite Belt sweep away below me in all directions (see above). Forty-six acres of those forests and hills belong to Wifie and me. It doesn't sound like a lot but, in several exploratory walks, we have not yet found all the boundaries and we still make amazing discoveries whenever we go wandering – granite bluffs, huge meadows, boulders as big houses, gorgeous, exotic plants (including three species of wild orchid so far) and beautiful forest glades. It is one of the most beautiful places I have ever seen – and I live there! The more gaudy bird-life includes crimson rosellas, king parrots, yellow-tailed black cockatoos, and eastern rosellas, and there are often wallabies in the 'garden' as well as feral pigs (not yet seen bet heard snuffling and grunting in the dark), lizards and snakes (including a gorgeous red-bellied black snake we found near the house the other day - see below). We've seen wild cats, a fox, rabbits and, in early Spring, the roads are full of long-necked turtles crossing at their leisure. The air is full of the sound of cicadas chirruping and, in the evenings, the frogs join in the song.

The ground immediately around the house has been cleared but nothing has been done with it so Wifie and I spend our time making plans for a garden. We've already planted a few fruit trees and we've put in some of the prettier native shrubs (grevilleas, bottle-brushes, banksias) but there is lots to do. Even this 'garden' is huge and we have to adjust to the idea that 'gardening' here will involve earth-movers and lorry-loads of materials. Our days of picking up a bag of gravel or mulch from the garden centre are over. Such things now need to be ordered by the cubic metre, delivered in trucks and spread by bobcat. Even the 'ordinary' garden tools are different now. Strimmers, mowers, weed-sprays and so on, that used to be adequate for a suburban home, we are replacing with heavyweight industrial equivalents. And, for the first time in my life, I own a chain saw and an axe. I got them so I could cut up wood for the wood-burning stove but now I see many other uses. A recent storm, which brought a small tree down across the drive a couple of weeks ago made me realise that a chain saw is an essential part of my new life. Without the means of clearing a fallen tree off your drive, you could be stranded up here!

And at night, when the skies are clear and the Moon is new, the Milky Way is a river of light that runs from horizon to horizon, turgid with stars - more stars than I have seen in my life before, more stars than I even knew were there. It is breathtaking. Astonishing. The glory of the Universe revealed just for the effort of lifting up your eyes! I watch satellites amble past, meteorites zip by, and whole galazies - the Large and Small Megallenic clouds - hanging like misty islands above me. And if you think I'm waxing a bit poetical here, all I can say is, you should see it and then we'll see who's totally blown away.

It's exciting, scary, humbling, and uplifting. It's a wonderful adventure and a dream come true. I am an immensely lucky person.

The Gray Wave Jukebox


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