Here’s a really clever prototype for home made water purifiers.
The designer won the Australian Design Award recently, so it has passed a lot of important conceptual and practical tests. And at a first glance it appears this purifier might be a real success story.
Prize winner, Julie Frost, from the University of New South Wales in Sydney, Australia, developed a cleverly shaped plastic bucket with a black polyethylene lining, that women in developing countries can fill at a well and then balance on their heads to carry home as they have traditionally done.
So far, nothing has changed. But when the precious water arrives home in Julie’s bucket, that she calls a mvura (Shona for ‘water’), the changes come thick and fast may loc nuoc ro gia dinh.
First, the lady places the bucket on the ground and it opens into a flat lotus flower shape. Amazing! The flexible black polythene lining spreads out, still holding all of its 15 liters of water, so nothing is spilled. This is then placed in the hot African sun … and Julie’s magic begins in this ingenious home made water purifier.
In just two hours the heat of the sun, amplified by the black plastic, heats the water to 65 degrees. The village water carrier knows when this temperature has been reached because some simple soybean wax will have melted. And when that has happened the water becomes pasteurized and harmful bacteria will be neutralized.
Julie has succeeded in adapting a bucket. But unfortunately she still has some way to go to develop a safe, reliable and effective home made water purifiers.
For one thing although polyethylene is a relatively stable plastic, if does break down in UV after about six months. There are UV stabilized polyethylenes available but they come with a price and I have not seen convincing research showing they last indefinitely.
Second, every expat housewife in a developing country will tell you that you need to boil water to get rid of the most heat-resistant pathogens — the amoeba giardia and cryptosporidium. When my family and I lived in a developing country for 10 years there was disagreement on just how long the water should be boiled. But everyone agreed that drinking water would only be purified if it was boiled. So Julie’s gentle heating of the water to 35 degrees less than boiling temperature doesn’t pass the amoeba test.
Neither, of course, did it do anything to filter the water at the well or river when the lady drew it up to fill her bucket. Pathogens and simple contaminants such as feces (and there are plenty of the latter in developing countries, I can assure you, from personal experience!) come into our water supply clinging to tiny, almost invisible particles in the water. So they need to be filtered out. Cloth might get rid of some of the larger particles in clean water supplies. Sand and gravel in a bucket might do the job if someone could tell the lady at the well how much sand and gravel the water should pass through and how slowly she should pour her precious water into the sand so it runs out the bottom filtered. Basically, too many problems at this end of the water procurement process.
Tablets of iodine or chlorine would make water clean. Indeed, my wife for many years put drops of iodine in water and soaked our salad vegetables in it whenever she prepared a meal with them. And I myself have used a portable water purifier that passed water through an iodine-impregnated substance into a cup. Ugh! Tasted horrible. Again, this is not going to improve these home made water purifiers.
Of course the obvious drawback with Julie’s bucket is that on a cloudy day, the lady and her family will not have clean water. Presumably they go thirsty and try again tomorrow.
But the major problem is that these home made water purifiers needs to be able to both remove the harmful elements that make drinking water unsafe (dangerous pathogens, man-made pesticide residues, feces and other contaminated particles) and still leave behind the natural trace minerals that our bodies simply must have to function properly. Julie’s bucket takes a clumsy swipe at one aspect of purifying water, but leaves the families who drink from it in great danger of contracting giardia and drinking the waste matter that washes into local wells from animal stables and the fields where village people traditionally go to toilet in the soft, protective darkness of early morning or twilight.
A better solution would be to give the village lady a sophisticated, modern water purifier fitted to a simple-to-use, robust dispenser. Perhaps Julie’s next project could be to develop this dispenser and find funding so the filters could be put into villages across vast swathes of needy countries. Julie’s home made water purifiers are a good first step in the direction of clean drinking water. But the journey of a thousand miles is before her, with a mountain of science and technology still to be climbed.