Environmental Engineering Reference
In-Depth Information
Water softening—
A chemical treatment method that uses either chemi-
cals to precipitate or a zeolite to remove the metal ions (typically
Ca
2+
, Mg
2+
, and Fe
3+
) responsible for hard water.
Watershed—
The land area that drains into a river, river system, or other
body of water.
Wellhead protection
—The protection of the surface and subsurface areas
surrounding a water well or well field supplying a public water sys-
tem from contamination by human activity.
DID YoU KNoW?
Americans drink more than 1 billion glasses of tapwater per day.
Clean, Fresh, and Palatable: A Historical Perspective
An early human, wandering alone from place to place, hunting and gather-
ing to subsist, probably would have had little difficulty in obtaining drink-
ing water, because such a person would—and could—only survive in an
area where drinking water was available with little travail. The search for
clean, fresh, and palatable water has been a human priority from the very
beginning. We take no risk in stating that when humans first walked the
Earth many of the steps they took were in the direction of a water supply.
When early humans were alone or gathered in small numbers, finding
drinking water was a constant priority, to be sure, but it is difficult for us to
imagine today just how big a priority finding drinking water became as the
number of humans proliferated. Eventually communities formed, and with
their formation came an increasing need to find clean, fresh, and palatable
drinking water, as well as a means of delivering it from the source to the
point of use.
Archeological digs are replete with the remains of ancient water systems
that reflect humans' early attempts to satisfy their never-ending need for
drinking water. For well over 2000 years, piped water supply systems have
been in existence. Whether the pipes were fashioned from logs or clay or
carved from stone or other materials is not our point—the point is they were
fashioned to serve a vital purpose, one universal to all human communities:
to deliver clean, fresh, and palatable water to where it was needed.
These early systems were not arcane. Their intended purpose is read-
ily understood today. As we might expect, they could be rather crude, but
they were reasonably effective, although they lacked in two general areas we
take for granted today. First, of course, they were not pressurized but instead
relied on gravity flow, as the means to pressurize the mains was not known at
