The true definition of "pure water" is H2O - 2 parts hydrogen to 1 part oxygen. However, "pure water" is expensive and very hard to find so water containing some degree of impurity is frequently termed "pure." Different individuals in various fields will use the term "pure water" when defining water that matches their need:

• A bacteriologist defines "pure water" to contain no living bacteria.
• A chemist defines "pure water" to contain no minerals, gasses or organic impurities.
• A public water supply defines "pure water" to meet the United States Environmental Protection Agency (EPA) standards in terms of its suitability for drinking (or potability).

There are great variations in the quality of water from area to area. The critical factor in water problems is that water is a natural solvent and it will dissolve a portion and collect part of whatever it touches, including:

• Metals
• Rocks
• Waste matter
• Gases
• Dust
• Foreign Substances

The dissolved content in water is termed impurities or contaminants. The varying degrees of contamination is what concern us. They are directly related to the problems being experienced and the way in which water can be treated.

The dissolved solids in water will vary. Heavy precipitation, seasonal weather conditions, decaying vegetation, irrigation, pollution or municipal pretreatment affect all sources of water.

EXAMPLE: The composition of 2 private wells only 5 feet apart can be entirely different as well as municipal water which can be drawn from 1 or more wells and/or can be a mixture of surface and well.

In addition, man-made water problems contribute to the situation and that leads to natural water problems. Ultimately, the water is being contaminated faster than nature can clean it!

Before the 1970's, most people were concerned with microbial contamination (taste and odor of the drinking water). Today, the news is full of reports focusing on chemical contaminants and the types of health hazards they cause.

Over 70,000 different water contaminants have been identified. Researchers say the principal sources of contamination are associated with the post World War II chemical age.