The work is to some extent a compilation of notes and quotations which have been collected by the author during years of study and teaching the subject. Credit has been given wherever due, and at the same time references have pointed out the original sources whenever possible. These references, which have been supplemented by brief bibliographies at the end of certain chapters, will be useful to the student and engineer interested in further study. Occasionally the original reference has been lost or the phraseology of a quotation has been so altered by class-room use, as to make it impossible to trace the original source, so that in some few instances full credit may be lacking. The author is indebted to many of his friends for their criticisms and suggestions in the preparation of the manuscript; but he desires particularly to acknowledge the assistance of Professor A. N. Talbot, Professor of Municipal and Sanitary Engineering at the University of Illinois, and of Professor M. L. Enger, Professor of Mechanics and Hydraulics at the University of Illinois, in the entire work; also that of Mr. T. D. Pitts, Principal Assistant Engineer of the Baltimore Sewerage Commission during the construction of the Baltimore sewers, for his suggestions on the first half of the book; and to Mr. Paul Hansen, consulting engineer, of Chicago, and to Mr. Langdon Pearse, Sanitary Engineer of the Sanitary District of Chicago, for their help on the section covering the treatment of sewage; and to Professor Edward Bartow, Professor of Chemistry at the University of Iowa, for his review of the chapter on Activated Sludge; in general his thanks are due to all others who have furnished suggestions, illustrations, or quotations, acknowledgments of which have been included in the text. H. E. B. URBANA, ILLINOIS, 1922. TABLE OF CONTENTS CHAPTER I INTRODUCTION PAGES 1. Sewerage and the Sanitary Engineer. 2. Historical. 3. Methods of Collection. 4. Methods of Disposal. 5. Methods of Treatment. 6. Definitions. 1–8 CHAPTER II WORK PRELIMINARY TO DESIGN 7. Division of Work. 8. Preliminary. 9. Estimate of cost. METHODS OF FINANCING. 10. Bond Issues. 11. Special Assessment. 12. General Taxation. 13. Private Capital. PRELIMINARY WORK. 14. Preparing for Design. 15. Underground Surveys. 16. Borings. 9–23 CHAPTER III QUANTITY OF SEWAGE