Generally infiltration has high initial rate that diminishes during continued rainfall towards a nearly constant lower rate. Water infiltration into soil media in various climatic conditions, soil properties and geological conditions which are very complex and as such a universal mathematical model is not available to address water infiltration. Methods available for quantification of infiltration are costly and laborious and not suitable for routine field use or laboratory use. Even soft computing tools available in the market are costly and hence there is a need to develop or utilize easily available soft computing tools to determine infiltration through soil. Mathcad as a mathematical soft computing tool works and feels very much like a Windows based word processor. Printed output from Mathcad is a document that can be easily read, understood, checked and reviewed. Numerous formulations and versions of infiltration models have then been developed for utilization with specific site conceptualizations, or boundary conditions. Few studies such as NRCS, Green Ampt, Kostiakov''s and Modified Kostiakov''s Equation are reported in this book.