The phrase "to salt the water" means to add salt to a body of water, usually as a way to preserve or enhance its properties. This can be done for various reasons such as preserving fish caught in freshwater bodies, preventing corrosion on boats and equipment, improving traction on icy roads, or treating swimming pool water. The addition of salt changes the density of the water, which affects how it interacts with other substances and can have various effects depending on the specific application.