What is Fresh Water?

Legal Definition
Fresh water is naturally occurring water on Earth's surface in ice sheets, ice caps, glaciers, icebergs, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and other total dissolved solids. The term specifically excludes seawater and brackish water although it does include mineral-rich waters such as chalybeate springs. The term "sweet water" (from Spanish "agua dulce") has been used to describe fresh water in contrast to salt water. The term fresh water does not have the same meaning as potable water. Much of the surface fresh water and ground water is unsuitable for drinking without some form of purification because of the presence of chemical or biological contaminants.
-- Wikipedia
Legal Definition
Water with an average low solids content. Measured at less than 1,000 milligrams or 1 gram of dissolved solids per liter or 1,000 grams or 1 kilogram water.