Headwater Posted on 15th November 20154th September 2020 by ThePD (The Project Definition) Headwater is the source and upper reaches of a stream that flows into a larger river. Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in HSE and tagged environment, water. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.