Abstract: A method and apparatus for blocking residual water lingering in pipes after the water has been shut off and substantially drained in a residential or commercial establishment just prior to soldering. A water soluble, able to disintegrate, low density, compressible, resilient, expanded starch based composition is used in combination with a residual water prevention kit which can be stored for extended lengths of time and carried with other soldering tools such as inside a tool box or in a pocket. A mat display apparatus made of the same or similar composition provides a scale of removable plugs for use on pipes having different diameters.