Water quality monitoring is vital in smart city planning for managing water resources. In the smart city, more data is being collected. In terms of data related to water quality, many data sources such as smart sensors attached to water quality monitoring systems have been continuously collecting a significant amount of data. The potential of collected data from these sources holds no value for smart cities, unless it is being used to provide digital services such as information about clean and safe drinking water, swimming, fishing, domestic uses, and water reuse. However, the knowledge on how to utilize water quality data for the benefits of smart cities is limited. So, in this paper, I propose digital water quality monitoring services for smart city residents. I explore this proposition through a design study engaging smart city residents, service designers, and developers of water quality monitoring systems. As a result, a service blueprint is presented to illustrate how such services can be designed to provide water quality information for different activities. The study aims to illustrate how opportunities of water quality monitoring system can be explored for smart cities. The study intends that the results are helpful to designers and researchers in designing and developing digital water quality monitoring services in smart cities.