Abstract: A cleaning method including an alkaline cleaning step followed by an acid cleaning step is used, for example, to treat a newly constructed ultrapure water distribution piping system (using PVDF piping system). The inherent inorganic and organic contaminants in the piping material as well as contaminants deposited (if any) during the construction phase can be removed efficiently. Therefore, the commissioning time of a newly constructed ultrapure water distribution system to meet the specified quality of contaminants can be shortened from several weeks to approximately one week.