For the past several decades the amount of water used increased 4-8 percent every year. Water will be reportedly more precious than oil worldwide in the future as agricultural water accounts for 70 percent and industrial water 20 percent in the amount of fresh water used.

According to a survey published by the UN, 884 million people do not use clean water at present worldwide and 5-6 million people die every year of diseases caused by foul water.

That is why many countries are paying great attention to the work to protect water resources and settle the water problem.