WATER ON EARTH Most water in Earth's atmosphere and crust comes from saline seawater , while fresh water accounts for nearly 1% of the total. The vast bulk of the water on Earth is saline or salt water , with an average salinity of 35‰ (or 3.5%, roughly equivalent to 34 grams of salts in 1 kg of seawater), though this varies slightly according to the amount of runoff received from surrounding land. In all, water from oceans and marginal seas, saline groundwater and water from saline closed lakes amount to over 97% of the water on Earth, though no closed lake stores a globally significant amount of water. Saline groundwater is seldom considered except when evaluating water quality in arid regions. How Much Water Is on Earth? Where is the water on Earth? Earth is unique because it has so much water. It’s in the ground, on the surface, i...