The water auditing is the process used to investigate the accounting of water available for the project, and its effective utilization in the system. It identifies various losses incurred in the system, such as field application losses, losses in the distribution or conveyance system, reservoir. These losses in the system are finally related with the irrigation supply and production with the help of various indices or indicators. The indicators used in the evaluation helps describe the current status of the project. The same is discussed in detail in this chapter with the help of worked examples from real irrigation projects.