AWWA QTC97154

Coliform bacteria can be carried in drinking water and dispersed throughout distribution systems. Bacteria may also adhere to or be released from pipe walls. A grab sample represents a snapshot of water quality at a particular location and time. Water quality may vary among sampling sites and visits. For these reasons, monitoring water quality in distribution systems is complex and it is often difficult to estimate water quality using simple methods. This paper describes the distribution system water quality monitoring program of the City of New York and presents a case study of the response to a recurrent coliform problem. The water quality monitoring program integrates routine monitoring activities with modeling, a geographic information system (GIS), data analysis and special investigations.