All possible means for new sources of fresh water must be used _______.

Our need for water is constantly increasing. There is an automatic increase due to population growth, the irrigation of more land for food production and the creation and expansion of new industries, all foretell
the need for even greater water supplies throughout the world. Though it is difficult to calculate the exact amount, it is safe to say that in 20 years time the demand for water will be roughly double. Faced with such a situation it is obvious that we should search as widely as possible and with every available means for sources of fresh water that seem to be the least costly. But where do these sources exist? Only a sustained and co-ordinated programme of scientific ….