The author is thankful to readers throughout India who have made this book so popular. He is thankful to professors and students of different Universities who send their valuable suggestions and author is hopeful that they will find this edition up to their satisfaction. Now a days shortage of water is being felt everywhere and that is why Govt. of India has made mandatory to make arrangement for Rainwater Harvesting in all buildings having plinth area 100 sq. m. and more. Looking at the importance of rainwater harvesting a chapter has been including in this edition. Presentation of the chapter has been influenced by several publications and the author is grateful to writers and publishers of the same. Finally author is thankful to his friends and the publishers for taking keen interest in the book. The author welcomes suggestions from users for further improvement of the book.