Surface water

From Trail-Finder -- Dedicated to getting you outside

Surface water is any fresh (non-salt) water on the surface. Unless you know otherwise, all surface water should be assumed to be contaminated and undrinkable. Fortunately, it can easily be made drinkable using one or methods of water purification, including the use of water filters, chemical water purification, or by bringing the water to a rapid boil for at least five minutes (more at higher altitude).