Even thousands of years ago, man knew the importance of water. At first, what interested most was the amount of water available. The man lived near his water source. Then, over time, more emphasis was placed on the aesthetics of water. In other words, how he smelled, tasted and looked. Nobody wanted to drink cloudy or smelly water. Thus began the search for pure drinking water.

Today you can make a homemade water purifier using inventions and innovations that began in ancient times. The methods used in Egyptian times to keep water clean are documented in writings and paintings found on tomb walls. These methods included some combination of boiling, filtering through sand and gravel, heating in the sun, or immersing hot iron in water.

Hippocrates, the father of medicine, invented the Hippocratic sleeve. This was a cloth bag that was used to remove some hardness and bad odors from the water that was passed to it. In the late 1600s, an Italian physician named Lucas Antonius Portius wrote extensively on multiple methods of sand filtration. In the early 1700s, La Hire, a scientist from France, suggested that every home should have a sand filter and rainwater cistern to keep the water pure and fresh.

Municipal water treatment began in Scotland and England in the early 1800s. Slow sand filtration was the method used in these early water treatment plants. At sites where these slow sand filters were used around London, officials noted a decline in cholera deaths during the epidemics of 1849 and 1853. The relationship between clean water and health was beginning to be understood around this time, and demonstrated that just because water tastes good and is clear it is not necessarily safe to drink.

So what exactly do slow sand filters do? Can the concept be applied to a home water purifier?

As the contaminated water is slowly added to the top, bacteria and other organisms are absorbed into the sand particles. The greatest concentration will be in the upper layers. On the surface of the sand, a layer of biological matter known as the “filtration cake” gradually forms. It is this biological zone that feeds on disease-causing insects when trapped. This highly effective way of killing pathogens has worked for centuries. Clean water comes out of the bottom.

According to the World Health Organization (WHO), more than a billion people lack access to a source of clean water. This fact is one of the main contributors to more than a million deaths each year due to diseases 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 more than one million people in 49 countries. Provides education and training to other charities serving the poor in developing countries. These charities show local people how to build a version of the slow sand filter using clay or cement pots and other local materials. It is a way to provide an effective yet low-cost means of providing better drinking water with a homemade water purifier.

With the Industrial Revolution came a whole new way of looking at water treatment. Chemicals dumped into our water supplies, and not just pathogens, were now part of the pollution problem. In a study published in December 2005, the Environmental Working Group found 260 contaminants in water served to the public, and more than half were unregulated. Much more sophisticated filter technologies are needed to remove harmful chemical contaminants.

While using a home water purifier can save lives and improve the quality of life in underdeveloped parts of the world, using one in a built-up setting is probably not a good idea.