This paper discusses a drinking water monitoring and surveillance program (Water Sentinel) and a laboratory netwrok tht would support it through the formation of an alliance of drinking water laboratories, the Water Laboratory Alliance, with the Laboratory Response Network (LRN). Specifically, the system will utilize information from water quality monitoring, public health surveillance, consumer complaint tracking, and other threat warnings. The design of the Water Sentinel contamination warning system will consider the following elements: reliability of each information stream; the time between the contamination incident and receipt of each information stream; the number and type of contaminants that might be covered by each system component; and, resource requirements for each system component.