Page 161 - Science Class 07
P. 161
etc). People who consume this water will household tasks.
become ill, and there is a risk of death. v Water used for washing vegetables must be
v The lack of potable water is o en accom- used for watering plants.
panied by other lapses in sanita on, such v Since pollu on is affec ng the quality of
as open sewers and limited garbage our daily lives, we must think and use
collec on. Many of these public health environment friendly processes to save our
issues impact the poor more than anyone planet.
else.
POLLUTION OF WATER
v Water which is contaminated can be
There are five major causes of water-pollu on:
treated to turn it into potable water.
v Sewage flow from homes, hotels and other
v One of the easiest ways to treat water is
buildings.
boiling. Boiling kills the germs present in
water. v Defeca on in the open fields. Rain-water
v Boiling water may not remove heavy
contaminants, but it can neutralize most
bacteria and viruses which may be present.
v Water can also be treated with chemicals
such as bleach, which some mes come in
the form of tablets for field and camping
use. In addi on, water can be pumped Sewage
through a filter to remove par culates. carries the filth to nearby water-bodies.
v Chlorina on is a commonly used chemical v Germs from filth and dung enter water and
method to purify water. pollute it.
v Chlorina on is done by adding chlorine v Dumping of factory-wastes (effluents) in
tablets or bleaching powder to water. water-bodies.
v We must be cau ous while adding chlorine v Excess of fer lizers, pes cides and insec -
tablets. cides used by farmers.
v We must not add more chlorine tablets PREVENTION OF WATER POLLUTION
than specified. The following steps help a lot to control the
v Laws for industrial units must be strictly water pollu on:
implemented so that polluted water is not v Filth and dung should not be allowed to
directly disposed into water bodies. reach the water-bodies.
v At our individual levels we must not waste v Pit-laterines should be used instead of
water. open dry-latrines.
v Reduce; reuse and recycle should be the v Sewage from homes, hotels etc. should be
thought of saving water. properly treated before being released into
v We can think of crea ve ideas like reusing water-courses.
water used for washing and for other v Dead bodies of animals should be disposed
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