Without water, life on Earth would not exist as water is essential for all living things. While it seems like there is plenty of water in oceans, lakes and rivers, most water on Earth is saltwater in oceans and only 3% is freshwater, with most locked in ice caps and glaciers. The limited freshwater resources are critical for human and agricultural uses but the total amount of water on Earth is fixed, being recycled over time rather than a replenishing resource.