The term "privy" as used in this article shall be understood to include any and all buildings which are not connected with a system of sewage or with septic tanks of such construction and maintenance as are approved by the State Department of Health and Environmental Control and which are used for affording privacy in acts of urination or defecation. For the purpose of this article the term "watershed" shall include the entire watershed of all streams, creeks and rivers that have a daily average flow of less than ten million gallons, but for watersheds of streams, creeks or rivers that have a daily average flow of more than ten million gallons, the watershed shall include only such drainage areas as lie within fifteen miles of the waterworks intake.