<P> As a result, the vast bulk of the water on Earth is regarded as 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 . </P> <P> The remainder of the Earth's water constitutes the planet's fresh water resource . Typically, fresh water is defined as water with a salinity of less than 1 percent that of the oceans - i.e. below around 0.35 ‰ . Water with a salinity between this level and 1 ‰ is typically referred to as marginal water because it is marginal for many uses by humans and animals . The ratio of salt water to fresh water on Earth is around 40 to 1 . </P> <P> The planet's fresh water is also very unevenly distributed . Although in warm periods such as the Mesozoic and Paleogene when there were no glaciers anywhere on the planet all fresh water was found in rivers and streams, today most fresh water exists in the form of ice, snow, groundwater and soil moisture, with only 0.3% in liquid form on the surface . Of the liquid surface fresh water, 87% is contained in lakes, 11% in swamps, and only 2% in rivers . Small quantities of water also exist in the atmosphere and in living beings . Of these sources, only river water is generally valuable . </P> <P> Most lakes are in very inhospitable regions such as the glacial lakes of Canada, Lake Baikal in Russia, Lake Khövsgöl in Mongolia, and the African Great Lakes . The North American Great Lakes, which contain 21% of the world's fresh water by volume, are the exception . They are located in a hospitable region, which is heavily populated . The Great Lakes Basin is home to 33 million people . The Canadian cities of Toronto, Hamilton, Ontario, St. Catharines, Niagara, Oshawa, Windsor, and Barrie, and the United States cities of Duluth, Milwaukee, Chicago, Gary, Detroit, Cleveland, Buffalo, and Rochester, are all located on shores of the Great Lakes . </P>

19. the majority of fresh water on our planet comes from