Rain water harvesting

As we all know that about 70 percent of the earth is water but most part of the earth is ocean. Only 3% of total water available on earth is fresh water. Out of the three percent, only 1 percent is accessible as surface fresh water where as the rest 2 percent is locked away in the form of ice caps and glaciers in the polar regions. 1 percent water is regularly renewed by rain fall and other means and thus available on a sustainable basis and easily considered accessible for human use.