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The figure below shows how water supplied to houses in cities is made fit for drinking.
It is important to have a source of good drinking water. Water found underground is referred to as ground water.
Question 1
Give one reason why there is less bacteria and particle pollution in ground water than in water from surface sources such as lakes and rivers.
The cleaning of water often happens in several steps, involving different techniques. The cleaning process shown in the figure involves four steps (numbered 1–4). In the second step, the water is collected in a settling pond.
Question 2
In what way does this step make the water cleaner?
A. The bacteria in the water die.
B. Oxygen is added to the water.
C. Gravel and sand sink to the bottom.
D. Toxic substances are broken down.
In the fourth step of the cleaning process, chlorine is added to the water.
Question 3
Why is chlorine added to the water?
Suppose that the scientists involved in the testing of water at the water plant discover that there are some dangerous bacteria in the water after the cleaning process is completed.
Question 4
What should people at home do with this water before drinking it?
Question 5
Can drinking polluted water cause the following health problems? Circle “Yes” or “No” in each case.
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