Page 160 - Science Class 07

v Do not throw away water that has been The collected water is seeped into the earth
used for washing vegetables, rice or dals. and groundwater is hence recharged.
Use it to water plants or to clean the floors,
etc.

v You can store water in a variety of ways. A
simple method is to place a drum on a
raised pla orm directly under the rainwater
collec on source. You can also collect water
in a bucket during the rainy season.

Rain Water Harves ng

POTABLE WATER

Potable water is also called drinking water.
v Water may be naturally potable, as in the

case with pris ne springs or it may need to
Plants make food through photosynthesis, it
be treated in order to be safe.
is sent back to all the parts of the plant
through a different plant- ssue that is called v In either instance, the safety of water is
phloem. assessed with tests which look for poten-
ally harmful contaminants.
The surplus water and oxygen le behind
unused is let off in the atmosphere. They v The issue of access to potable water is very
join their respec ve cycles in nature. important.
Remember that, the earth has as much v In developed countries, people may not put
water on it as it had millions of years ago. a great deal of thought into the source of

their water.
RAIN WATER HARVESTING
v In many na ons, ci zens can turn on a tap
Rain water harves ng is a technique to for fresh, potable water which may also be
recharge groundwater. Most of the rain water enriched with substances for health.
in towns and ci es is not u lised in any way.
v In developing countries, however, and
This water generally goes out of the ci es
especially in Africa, a large propor on of
through drains. To make use of this water this
the popula on does not have access to safe
technique has been adopted. In this technique,
water.
rain water is collected in a low laying land or
ditches through pipes connected to the roofs of v Water which is not safe to drink can carry
the houses. diseases and heavy metals (lead, mercury,

160 Science-7