Read the following text! Then answer the questions!

    Water is life. If there were no water, there would be no life. Do you know all life forms of all species of flora and fauna are able to live because of water? Water is the major component of building blocks of life, food, metabolism, and functioning of every living being and organism. Living this wonderful life is impossible without water.

    First, water is indispensable for life. Water is the force behind all the industry, agriculture, manufacturing, trade and commerce. All forms of energy are done using water. Be it hydroelectrically projects, or thermal power plant, or nuclear power plant, water is the key ingredient in all of them. There would be no power without water.

    In addition, the harsh reality is we are doing nothing to save it. Our natural water bodies such as rivers, lakes, and oceans, have been turned into huge sewage channels and drains. The underground water has been terribly contaminated. It appears soon there won't be left any good water in the world.

    It is our responsibility to conserve this life nectar. It is possible only through by changing our outlook towards this wonderful natural resource. We must ensure there is no pollution of water bodies by dumping any waste, such as sewage, effluents, and other toxic substances. The people and the government must ensure installation of effluents and smoke treatment plants at industrial garbage, and sewage units. All people should make efforts to conserve water.

(Taken with some changes from: Oswaal CBSE Question Bank Class 12 English Core Chapterwise & Topicwise.)

"... water is the key ingredient in all of them."

What does it mean?