Abstract: A flexible under sink liner having a bottom, sides, and an extension from at least one of the sides is disclosed. The liner forms a fluid retaining vessel to collect fluids or other substances preventing damage to nearby structures or chemical or biological health hazards. The liner's side extension contacts the surface against which it is installed and guides fluids flowing down the surface into the liner's vessel. Various embodiments of the liner may include various combinations of raised textures on the liner's bottom to allow for better fluid evaporation. In addition, the liner's side extension may include fluid guides to prevent fluids from escaping the liner by flowing off the ends of the side extension. The liner may be reinforced in various ways such as by increasing the thickness of at least a portion of the flexible material where reinforcement is desired or by incorporating less flexible materials into the liner.