A core functionality of Wireless Sensor Networks (WSNs) is to transport information from the network to the application/user. The evolvable application reliability requirements and the fluctuating perturbations lead to continuous deviation between the attained and desired reliability. Using an existing approach that guarantees a highest reliability is not appropriate for WSN as this over-provisioning wastes the most valuable resources, e.g., energy. In this paper, we present a new approach called as Tunable Reliability with Congestion Control for Information Transport (TRCCIT) in WSN. To provide probabilistically guaranteed tunable reliability TRCCIT implements localized techniques such as probabilistic adaptive retransmissions, hybrid acknowledgment and retransmission timer management. TRCCIT pro-actively alleviates the network congestion by opportunistically transporting the information on multiple paths. TRCCIT fulfills application reliability requirements in a localized way, which ...