Water is essential to life, but also provides the broadest of services without which human society could not function. Since the start of the industrial revolution, global water usage has continued to increased many-fold. Current patterns of freshwater use cannot be sustained if the human population maintains its rate of growth. Many more countries could suffer from chronic water shortages due to rapid population growth, and possible disadvantageous climatic changes. Competition for water resources is growing and exceeding institutional capacity to manage it, as well as leading to more environmentally degrading water diversion, retention and extraction methods such as damming. In most countries, irrigated agriculture is the main consumer of water. As with irrigation, other water uses are often mismanaged and can lead to consequences such as gross over usage and waste of water, salinization, overpumping and land subsidence. Throughout the world, water quality is impaired by pollution and misuse, and water pathogens are the biggest killer and cause of disease in lower-income countries.
Global water withdrawal has increased an estimated thirty-five-fold during the last three centuries, and is projected to increase by 30-35% by 2000. Irrigated agriculture accounts for about seventy percent of world water withdrawal, but less than half of the water supplied contributes to crop growth. Many countries suffer serious water shortage. Water diversion, extraction and retention are having increasingly severe impacts on ecosystems.