Query processing has become one of the main paradigms to approach information processing in Wireless Sensor Networks (WSNs). We study and identify relevant factors involved in in-network query deployment in WSNs. As a key outcome, we developed a deployment aware cost estimation model for distributing operators to nodes within the network using the network lifetime as a key metric. In contrast to related approaches, we include the state of each node in the cost model. This provides means for an automatic load balancing mechanism that allows us to insert a higher number of queries compared to other approaches, thus, signiﬁcantly extending the network lifetime.