Even thousands of years ago, man knew the importance of water. At first, how much water was available was of most interest. Man lived near their water source. Then, with time, emphasis was placed more on the aesthetics of the water. In other words, how did it smell and taste and look. No one wanted to drink turbid or smelly water. So the search for pure drinking water began.
A home made water purifier can be made today using inventions and innovations that started in ancient times. Methods used in the time of the Egyptians for keeping water clean are documented in writings and paintings found on the wall of tombs. These methods included some combination of boiling, filtering through sand and gravel, heating under the sun, or dipping heated iron into the water.
Hippocrates, the father of medicine, invented the Hippocratic sleeve. This was a cloth bag used to remove some hardness and bad odor from the water put through it. In the late 1600's an Italian physician named Lucas Antonius Portius wrote extensively about multiple sand filtration methods. In the early 1700's, La Hire, a scientist in France, suggested that every household should have a sand filter and a rain water cistern to keep the water pure and fresh.
Municipal water treatment began in Scotland and England in the early 1800"s. Slow sand filtration was the method used in these early water treatment plants. In places where these slow sand filters were used around London, officials noticed a decrease in cholera deaths during the epidemics of 1849 and 1853 . Around this time the relation between clean water and health was just beginning to be understood. It was also shown that just because water tastes good and is clear it is not necessarily safe to drink.
So what exactly do slow sand filters do, and can the concept be applied to a home made water purifier?
As contaminated water is slowly added to the top, the bacteria and other organisms absorb into the sand particles. The greatest concentration will be in the top layers. On the sand surface, a mat of biological matter known as the "filter cake" forms gradually. It is this biological zone that eats the disease causing bugs as they are trapped. This very effective way to remove pathogens has worked for centuries. Clean water comes out at the bottom.
According to the World Health Organization(WHO) more than one billion people lack access to a clean water source. This fact is one of the major contributors to the over a million deaths each year due to disease from contaminated water and poor sanitation. Most of these deaths are children.
The Center for Affordable Water and Sanitation Technology (CAWST) is a Canadian charity that has improved drinking water for over a million people in 49 countries. It provides education and training to other charitable organizations that serve the poor in developing countries. These charities show the local population how to build a version of the slow sand filter using clay pots or cement and other local materials. It is a way to provide a low cost but effective means to provide better drinking water with a home made water purifier.
With the Industrial Revolution came a whole new way to look at water treatment. Chemicals dumped into our water supplies and not just pathogens were now part of the pollution problem. In a study released in December 2005, the Environmental Working Group found 260 contaminants in water served to the public, with more than half being unregulated. Much more sophisticated filter technologies are needed to remove harmful chemical contaminants.
While the use of a home made water purifier can save lives and improve the quality of life in undeveloped parts of the world, using one in an urbanized setting probably is not such a good idea.
