DIY Clay Filters: Safe Water for All

Unsafe drinking water is an ongoing problem in many parts of the world. And it's getting worse.Thanks to adverse climatic changes, the availability of potable water could become an issue in industrialized nations as well as developing countries--maybe even where you live.

THE ADVERSE EFFECTS OF DIRTY WATER

What do people do when clean drinking water isn't available? They drink unsanitary water--with disastrous results.

According to the World Health Organization (WHO), unsafe water causes approximately 2 million people to die annually from diarrhea alone. Nineteen other potentially deadly diseases, including cholera and cancer, are also attributable to unsafe drinking water. And it isn't just bacteria that makes water unsafe to drink. High levels of fluoride and arsenic are also harmful. (For more WHO "Facts and Figures on Water Quality and Health," click here.)

It's not surprising then that people who care about the welfare of others are working to make safe drinking water available around the globe.

MAKING CLEAN WATER AVAILABLE TO ALL

Kiln-Fired Clay Water Filters

Engineers Without Borders and Potters for Peace make inexpensive ceramic filters following a design created by Fernando Mazariegos, a chemist from Guatemala.The entire unit--including the water receptacle and a clay water filter--is sold in developing countries for $25 or less. By themselves, the filters cost $6 or less.

The filters are basically handleless buckets made from pressed clay, sawdust and other organic combustibles, such as coffee grounds and rice husks. The pressed clay mixture is fired in a kiln at 860 degrees Celsius, which causes the combustible material to burn away, leaving a porous clay filter. After firing, the filters are coated with colloidal silver, which is a bactericide.

The filter fits into a five-gallon receptacle, usually made of plastic or clay. It has a faucet and a lid and filters 1.5 to 2.5 liters per hour.

DIY Clay Water Filters

Tony Flynn of Australian National University (ANU) has designed a clay water filter that's even more accessible to the world's poor. It doesn't have to be fired in a kiln or coated with colloidal silver in order to effectively purify water. It requires no special equipment or skill to make either, and it's comprised of materials that are readily available in developing countries where sanitary water is scarce. The design, which is not patented, is free for everyone to use. The Australian nonprofit organization Abundant Water promotes the use of this design in areas of the world that lack clean water.

Flynn's water purifier is made using clay, straw, miscellaneous organic matter, water and manure. The organic material is mixed with clay and water and then "cooked" on a bed of burning dung. As the filter bakes, the organic materials burn away, leaving small pores in the filter that allow water, minus harmful pathogens like E. Coli , to pass through. According to ANU, the filter removes between 96.4 and 99.8% of all E. Coli pathogens. It does the job quickly too, although not instantaneously, filtering a liter of water in two hours.

What materials are needed?

• dry clay, crushed
• organic matter, such as rice husks, coffee grounds & tea leaves
• water
• straw
• cow or horse manure

How's it done?

First, the clay is mixed with water to form a stiff "batter." Then, it's formed into a cylindrical pot with one closed end. Next, the pot is allowed to dry in the sun. When it's completely dry, it's set in straw in a mound of manure. The straw is lit, and the fire is kept burning for about an hour. Sometimes, more manure must be added. After an hour, the clay water filter is ready to use.