1. Water Purification By Sam Swidler

2. How much water is on this planet? Water covers at least 71% of the Earth's surface. It is impossible to tell exactly how much water is on Earth due primarily to the vast size of the Earth and also the amount of water in the air in the form of water vapor.

3. And how much water is usable? Even though most of the Earth's surface is water, only 1% of it is fresh usable water. Ninety-seven percent of the Earth's water is saltwater, which contains too many minerals for humans to use untreated. Two percent of our water is "locked up" in ice caps and glaciers, leaving only one percent as usable fresh water.

4. What is Purified Water? Purified water refers to all types of water from which chemicals are removed via a variety of different processes. The simplest of these processes are available to consumers with water filters that help sort out some of the chemical compounds found in tap water. Other more expensive filters use a reverse osmosis technique, which helps shunt chemicals in the water to the side while leaving the remaining water free of most commonly, found chemicals.

5. Purification & how it works How do you purify water? Step One The first step of water purification is often ion removal, or softening. This processes uses holding containers that are negatively charged. Water is pumped into these containers. If there are metal particles present in the water, they are pulled toward the negatively charged areas and cannot escape. This prevents the metal traces from entering the water supply. Common metals that are eliminated during this step include iron and mercury. These substances cause health issues, if consumed, and can damage water pump systems as well.

6. Purification & how it works How do you purify water? Step Two The second step uses carbon to filter water. A layer of carbon serves as a filter and water must pass through it to continue through the filtration process. Harmful substances like chlorine and pesticides are generally absorbed at this stage of the process. If the carbon becomes over- saturated with contaminants, it can stop working and release toxins back into the water supply. Because of this, fresh carbon is cycled regularly. Step Three Water passes through a paper filter designed to remove sediment and catch large particles of dirt. This filter can catch particles smaller than people are able to see. While dirt is often not toxic, it can create problems for filter machinery during later steps.

7. Purification & how it works How do you purify water? Step Four During reverse osmosis, water moves through a very tight filter. On one side the water is filled with impurities and on the other side the water is clear. The two sides begin to balance each other out, watering down any present particles in the process. Often, several separate osmosis filters are used. This way, any particles that escape filtration are caught the second time. Step Five Here, another carbon filter is used. This filter is smaller than previous filters, and catches very tiny contaminants found in the water. Because the filter is made from carbon, it can not only screen for particles, but also absorb any remaining toxins.

8. Purification & how it works How do you purify water?. Step SixUV light is used as an antibiotic in this stage. High-energy light is focused to destroy any organisms that have survived the process. Because light is used instead of harmful substances, the water remains untainted and drinkable. –Step Seven –A third, even smaller micro filter is used as an extra measure of purity protection. This is the final filter used in the process, and ensures that no random contaminants can enter the system during maintenance or other problems. Step Eight –The last step in the purification process is ozonation. This infuses the water with a form of oxygen, which protects it from any future microbes. High-voltage power is combined with rich oxygen, creating ozone. This ozone kills harmful microbes on contact. Because it is unstable, the ozone in the water becomes natural harmless oxygen after several minutes. This short time, however, is all that is needed for the process to be successful, and to keep drinking water protected.

9. Comparison Comparison The percentage water in Ohio is 8.7. Together, the systems deliver approximately 1.4 billion gallons of water each day to nearly 9 million people in New York City and Westchester Orange, Putnam and Ulster counties.

10. Discussion Questions Discussion Questions Do you think it’s better to purify water? What examples of purified water can you think of? Are their any reasons not to purify water? In what ways does purified water affect us? Based on what you know, how would you explain purified water?

11. Links  http://wiki.answers.com/Q/How_much_water_is_on_earth http://wiki.answers.com/Q/How_much_water_is_on_earth  http://www.crwcd.org/page_143 http://www.crwcd.org/page_143  http://www.ehow.com/how-does_5220655_eight-steps-involved-water-purification.html http://www.ehow.com/how-does_5220655_eight-steps-involved-water-purification.html  http://www.epa.gov/Region2/water/nycshed/ http://www.epa.gov/Region2/water/nycshed/