The book has its origin when I was an academic at Flinders University. Some Australian students, and many overseas students, seemed to be having difficulty with the jargon. To overcome this obstacle I started giving a glossary as a hand-out of a few pages. With each successive year the glossary expanded more and more until it reached the stage when I thought I might as well turn it into a technical dictionary for the benefit of both students and the many in-career professionals. The first edition was quite well received, but that was 20 years ago, and it is now starting to look distinctly dated. Also, in the intervening period the entire jargon of the water sector has expanded and evolved so, in response to several peoples suggestion of a revise3d updated and expanded edition, here it is.