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People build special constructions which help them to conserve water. To provide storage for drinkable water people often construct dams. They are used all over the world. Besides, another reason for their construction is producing electricity. Farmers also use water for agricultural needs. Moreover, they help to control floods. Over $2 trillion has been spent on making dams worldwide.

• Special structures.
• Ocean waves.
• Using water efficiently.
• Water cycle.