Low Cost Methods of Water Purification

by Bhavani Prakash

This article has been written in support of BLOG ACTION DAY 2010, an annual online event where bloggers of the world unite to write on a specific issue on the same day, namely 15th October.  This year’s topic is WATER and there are over 4000 blogs from more than 130 countries participating today reaching in excess of 32 million readers.

My curiosity in the way pure drinking water can be made available to those with little access to it, was piqued by this image of a woman in the Vamdse village in Karnataka harvesting rainwater with a saree. This method is also followed by villagers in Kuttanad, Kerala.  It’s a simple improvisation, a local solution, and quite ingenious. (Source: India Together.org)

The villagers also boil the water before drinking.  Using garment cloth such as linen, cotton and other cloth folded several times is a simple way for water purification. While it filters solid particles, microbes and pathogens larger than 20 microns, including 99% of the V. Cholerae, it does not remove chemical contaminants or dissolved compounds.

According to the World Health Organisation, water borne diseases are the major cause of death in the world. Here are some quick facts from the UN Human Development Report 2006 and the GOOD: Water video that show how millions of people in the world suffer from the effects of unsafe drinking water.

• About 1.1  billion people in developing countries lack access to water, with 2.6 billion without basic sanitation
• Diarrhoea kills 4,100 children every day or 1.8 million children a year,  90% of whom are under 5 years of age. Each year, 443 million school days are lost due to diarrhoea and water-related illnesses.
• Nearly half of all people in developing countries suffer from a water or sanitation related health problem. Diarhhoea episodes can be reduced by half by household treatment.

How can cheap and affordable solutions be made available to the poor to improve water quality, prevent disease and save lives? Here are some very interesting examples which can substantially reduce the risk of disease, even though they may not completely eliminate the dangers from chemical contaminants.

1.   Moringa (moringa oleifera) is often called a “miracle tree” or the “world’s most useful tree“  because of its ability to provide an amazing variety of nutrients. It grows easily and in dry conditions, and is a low cost nutrition source for millions of poor. The seeds (of the commonly known drumstick pods) can be used as well as an affordable water purification method.

2. Abundant Water is an NGO based in Thailand, which helps communities get safe drinking water using local clay and coffee grounds and baked in a cow dung fire. The clay pots remove harmful bacteria and protozoa, and is such a simple, local solution.

3.  Life Straw – it’s portable, and kills 99.9% of the disease carrying microbes. It has 4 different filters,  the first is a textile 15 micron pre- filter that sieves out dirt and sediments. The second is a halogen based resin filter to remove bacteria on contact. The third filter stops viruses and parasites. The last is a carbon filter which improves taste and smell. Each LifeStraw can purify 700 litres of water or about 2 litres a day. It costs about US $3 to $5.

4. The WaterCone

This is a simple desalination method which evaporates salty or brackish water, and recaptures salt-free water through condensation. The black pan at the base meaures 60-80 cms in diameter. Water is poured on the pan and exposed to sunlight for the day. Clean water droplets accumulate on the cone and can be captured by inverting the cone. This can yield more than a litre of water a day. The cone is made with UV-resistant polycarbonate plastic, it’s nontoxic and recyclable with a life expectancy of 5-7 years. It costs about US $25 a piece.

5. BioSand Water Filter: Inside a concrete box is a filter which is made up of  a layer of gravel over which sand is overlain.  A shallow layer of water sits on top of the sand, where a biofilm (schmutzdecke) is created. This helps further filters the water of harmful microorganisms.

6. Terafil Terracotta Filters offer hope for clean drinking wter in villages in Jharkand, India. It’s “a red porous media produced from a mixture of red clay, river sand and wood saw dust. The dough of the mixture is sintered at high temperature in a low cost coal/wood fired furnace to make the terracotta disk porous.  It would cost about Rs 350 to Rs 500.”

Further Links you may be interested in :

Safe Water International.org : Low Cost Water Purification Sytems

The Next 4 Billion: The Water Market

YouTube: Rain Catching through Johads - Rajendra Singh

TED: Michael Pritchard makes filthy water drinkable

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