Permeable Interlocking Concrete Pavements (PICP) offer both environmental and economic benefits compared to conventional pavements. After discussing these benefits this paper outlines the development of a new computer based mechanistic analysis for the design of PICP. The method is based on surveys of user requirements for PICP and seeks to address such factors as storm water management, water quality and water harvesting as integral parts of the pavement design process. In other words the method is designed to integrate with modern concepts of sustainability and water sensitive urban design. To illustrate the scope of the method the application of PICP to a wide range of common pavement problems is summarised and the benefits are discussed.