NFPA's Fire Sprinkler Initiative provides the latest research underscoring how home fire sprinklers impact water supply.

Fire Flow Consumption in Sprinklered and Unsprinklered Buildings: An Assessment of Community Impacts

NFPA, 2012
Over the past 30 years, selected municipal water authorities have implemented strategies, including standby fees and other policies, to recover costs for water consumed in fires in sprinklered buildings. Typically these fees are not directly related to sprinkler fire flows but rather are recognition of the fact that these flows are not metered and thus not accounted for in conventional water cost recovery mechanisms. In contrast, water consumption at fires at unsprinklered properties is typically not subject to fees nor metered at the hydrant. NFPA commissioned this study to assess the relative community impacts of water consumption in sprinklered and unsprinklered properties. 

Integration of Residential Sprinklers with Water Supply Systems 
NFPA, 2009
This research develops objective data which characterizes the manner in which residential fire sprinklers are integrated with local water supply systems in communities with a sprinkler ordinance. The study explores these issues in detail through interviews with 20 communities where residential sprinklers are required in all new homes.