Pure water (H20) consists of 11.1888% hydrogen and 88.812% oxygen by weight. Although the term "pure water" is used commonly, it is virtually a non-existent liquid due to its aggressive nature. Water is often referred to as a "universal solvent" because of its ability to dissolve almost anything it comes in contact with. The superior solvent action of water allows it to be easily contaminated by water soluble materials. Water is considered to be "contaminated" when it contains harmful or objectionable substances which may be dissolved, suspended or biological.