An adequate supply of clean water is essential
to our health and well-being. We can live without food for many days, but life
would end in only a few days without water. Our circulatory system is an
aqueous stream that distributes an amazing variety of substances throughout the
body. Our cells are filled with water solutions in which the chemical reactions
of life take place. Without water and its unique properties, life would not be
possible on Earth
Three-fourths of Earth’s surface is covered with water,
which gives the planet a blue color when it is viewed from space. The oceans
represent the world’s largest liquid solution. Water participates in most of
the chemical reactions that occur in nature. Most water used for human
consumption comes from reservoirs, lakes, rivers, and wells. Much of this water
is used and reused by numerous cities as it travels downstream. Such reused
water may become seriously polluted with waste from previous users and with
pathogenic microorganisms.
As a safety precaution, most of the water we use
undergoes chemical and physical treatment to purify it. This treatment process
includes settling, whereby specific materials are added to bring down suspended
solids. This is followed by filtration through sand and gravel to remove still
more suspended matter. The filtered water may then be aerated by spraying it
into the air. This part of the treatment process removes some odors and
improves the taste of the water. Charcoal filtration, a treatment process that
is gaining in use, also removes odors along with colored materials. In a final
step, chlorine or another disinfectant is added to kill any remaining bacteria.
undergoes chemical and physical treatment to purify it. This treatment process
includes settling, whereby specific materials are added to bring down suspended
solids. This is followed by filtration through sand and gravel to remove still
more suspended matter. The filtered water may then be aerated by spraying it
into the air. This part of the treatment process removes some odors and
improves the taste of the water. Charcoal filtration, a treatment process that
is gaining in use, also removes odors along with colored materials. In a final
step, chlorine or another disinfectant is added to kill any remaining bacteria.
The treatment of water before use is an important
safety precaution.
safety precaution.