Tapping our water supplies

H2O. Two atoms of hydrogen and one atom of oxygen, are all that make up the most important substance to all living things on earth.
Water, as it is more commonly known, has a slight hint of blue in its most pure form and is known to be the most universal solvent. In its three states, water takes on many different forms: water vapour and clouds in the sky, waves and icebergs in the sea, glaciers and aquifers on land to name a few.
  
Earth’s water is 97% saltwater and undrinkable for humans. The other 3% is freshwater or potable water but of which, 2% is frozen in glaciers and polar icecaps. Our bodies are made of about 65% water making it vital our health. To function properly the body requires between one and seven litres of water per day to avoid dehydration.
  
By means of evaporation, precipitation and run-off, water is constantly changing from one state to another, in what is know as the hydrologic cycle. Run-off is the flow of water after rain which recharges ground water or aquifers. In many countries water is becoming scarcer as human population in those places increases, and its availability is a major social and economic concern.
  
The increasing amount of pollutants found in water are also becoming a greater cause for concern as more contaminants, such as fertilizers and chemical waste, are found in our water supplies.
  
Gone are the days, in many developed nations, where municipal tap water is considered safe for drinking.
  
Here are a just few commonly found, unwanted contaminants:

Chemical  

• Lead -  Found in water supplies with lead solder or pipes, especially when water is soft or corrosive. While lead is never desirable, concentrations greater than 15 micrograms per litre (15 ug/L also known as parts per billion or ppb) can cause brain, nerve, and kidney damage, especially in young children.


• Nitrate Nitrogen - Nitrate nitrogen is commonly used lawn and agricultural fertilizers. It is also a chemical formed when decomposing waste materials, such as manure or sewage.


• Fluoride –  Added to water to reduce tooth decay but controversy surrounds exists over its benefits and dangers. In low quantities fluoride is use commonly in health applications but levels found in water should be monitored and known.

Bacterial and Parasite

• Cryptosporidium - is a parasite commonly found in lakes and rivers, especially when the water is contaminated with sewage and animal wastes.


• Escherichia coli -  (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals and are necessary for the proper digestion of food. Its presence in groundwater is a common indicator of fecal contamination.

Bottled Water  

Today, because of a much increased awareness of water contaminants, more often people are drinking bottled water, or filtering water for consumption. Bottled water can be categorised into three sources:

1. Spring water - Derived from an underground aquifer from which water flows naturally to the earth's surface. Spring water must be collected only at the spring or through a borehole tapping the underground formation feeding the spring. If some external force is used to collect the water through a borehole, the water must have the same composition and quality as the water that naturally flows to the surface.


2. Mineral water – Water from an underground source that contains at least 250 parts per million total dissolved solids. Minerals and trace elements must come from the source of the underground water. They cannot be added later.


3. Purified water – normally comes from municipal sources - in other words - the tap. Municipal water is usually treated before it is bottled.

  
As can be seen, there arises many questions to the authenticity of bottled water label advertising. If you drink bottled water, always read the small print to see where it came from or what it "claims" to be.

Another way of removing unwanted contaminants in water is by filtration.

Filtering and Purification  

Filtering and purification don’t need to much explaining as to what they do but what must be pointed out, is the many different types and their effectiveness against different contaminants.

• Boiling - Water heated to its boiling point for one minute kills micro organisms that normally live in water at room temperature.


• Carbon filtering: Carbon with a high surface area due to its mode of preparation adsorbs many compounds, including some toxic compounds. Water passed through activated charcoal removes contaminants.


• Distilling: - Involves the boiling of water producing water vapour, leaving behind contaminants. The water vapour then rises to a cooled surface where it condenses back into a liquid to be collected. Although this method does not completely purify, it produces 99% pure water.


• Reverse osmosis: Pressure is applied to contaminated water forcing it through a semi-permeable membrane. Reverse osmosis is said to be the most thorough method of large-scale water purification.

  
There are many more water purification methods which are also effective but depending on which geographic location they are used, each one must be studied before making a decision on the best one.
  
Earth’s water, more than ever is becoming an important subject, especially when 1 in 6 people on the planet do not have access to safe drinking water.
  
Maybe before studying water on Mars, we should take a closer look at what is happening to our own - right here on earth.