Water and Water Pollution - Environmental Science - page 267

Most developed countries have laws establishing
drinking water standards, but most developing coun-
tries do not have such laws or do not enforce them.
Areas in developed countries that depend on sur-
face water usually store it in a reservoir for several
days. This improves clarity and taste by increasing dis-
solved oxygen content and allowing suspended mat-
ter to settle.
Next, the water is pumped to a purification plant
and treated to meet government drinking water stan-
dards. In areas with very pure groundwater sources,
little treatment except disinfection is necessary.
Simple measures can be used to purify drinking
water. In tropical countries that lack centralized water
treatment systems, the WHO urges people to purify
drinking water by exposing a clear plastic bottle filled
with contaminated water to intense sunlight. Heat and
the sun's UV rays can kill infectious microbes in as lit-
tle as 3 hours. Painting one side of the bottle black can
improve heat absorption in this simple solar disinfection
method. Where this measure has been used, incidence
of dangerous childhood diarrhea has decreased by
30-40%.
In Bangladesh, households receive strips of cloth
for filtering cholera-producing bacteria from drinking
water. Villages using this approach have cut the num-
ber of cholera cases in half.

Buyers should check out companies selling water
purification equipment and be wary of claims that the
EPA has approved a treatment device. Although it does
register such devices, the EPA neither tests nor ap-
proves them.

x

H OW W OULD Y OU V OTE ? Should pollution standards
be established for bottled water? Cast your vote online at
http://biology.brookscole.com/miller11.

Solutions: Reducing Water Pollution
Shifting our priorities from controlling to preventing
and reducing water pollution will require bottom-up
political action by individuals and groups.
Encouraging news. Since 1970, most developed coun-
tries have enacted laws and regulations that have
significantly reduced point-source water pollution.
These improvements were largely the result of bottom-
up political pressure on elected officials by individuals
and organized groups. Conversely, little has been
done to reduce water pollution in most developing
countries.
To environmental scientists, the next step is to in-
crease our efforts to reduce and prevent water pollu-
tion in developed and developing countries by asking
this question: How can we not produce water pollutants in
the first place? Figure 11-35 lists ways to achieve this
goal over the next several decades.

Science: Is Bottled Water the Answer?
Some bottled water is not as pure as tap water and
costs much more.
Despite some problems, experts say the United States
has some of the world's cleanest drinking water. Yet
about half of all Americans worry about getting sick
from tap water contaminants, and many drink bottled
water or install expensive water purification systems.
Studies reveal that in the United States bottled wa-
ter is 240 times to 10,000 times more expensive than
tap water, about one-fourth of it is simply tap water,
and bacteria contaminate about one-third of such wa-
ter. Other countries, however, must rely on bottled wa-
ter because some of their tap water is too polluted to
drink.
Before drinking expensive bottled water and buy-
ing costly home water purifiers, health officials suggest
that consumers have their water tested by local health
authorities or private labs (not companies trying to sell
water purification equipment). The goals are to iden-
tify what contaminants (if any) must be removed and
determine the type of purification needed to remove
such contaminants. Independent experts contend that
unless tests show otherwise, for most urban and subur-
ban Americans (or people in other countries) served by
large municipal drinking water systems, home water
treatment systems are not worth the expense and main-
tenance hassles.

Solutions

Water Pollution

• Prevent groundwater contamination

• Greatly reduce nonpoint runoff

• Reuse treated wastewater for irrigation

• Find substitutes for toxic pollutants

• Work with nature to treat sewage

• Practice four R's of resource use (refuse, reduce,
recycle, reuse)

• Reduce resource waste

• Reduce air pollution

• Reduce poverty

• Reduce birth rates

Figure 11-35 Solutions: methods for preventing and reducing
water pollution. Critical thinking: which two of these solutions do
you believe are the most important?