Communication patterns define the energy depletion profile of a wireless sensor network. In particular, routing defines which areas of the sensor field are subject to a higher traffic load. In these areas, sensor nodes deplete faster than in areas with a low traffic load. As nodes deplete, their batteries have to be replaced incurring maintenance costs. This paper presents an analysis framework of routing protocols that can be applied to produce sensor fields that are much less expensive to maintain. The framework is based on a maintenance model that is simple, yet flexible enough to capture real world deployment scenarios of sensor networks. As an illustration, the framework is used to assess the impact of different forwarding techniques for a known geographical routing protocol on the overall maintenance costs of different sensor fields. The results obtained indicate that an one-size-fits-all approach for the design of maintenance efficient routing protocols does not hold in large deployments of wireless sensor networks. However, savings of up to 50% in maintenance cost were observed through simple modifications of the forwarding strategy.