In most cities across the nation, the water distribution system is more than 50 years old. Facing aging, often failing assets, a sound strategy is required to plan for investment and maintenance, including pipe replacement and water pricing.

A new study, “Setting Future Water Rates for Sustainability of a Water Distribution System” in the Journal of Water Resources Planning and Management, introduces a hybrid-SD model, combining the hydraulic analysis tool EPANET and a feedback SD model loop, to quantify the investment needs required. The paper was written by Seungyub Lee, Ph.D., A.M.ASCE; Christine Pomeroy; and Steven Burian, Ph.D., P.E., M.ASCE.


This study introduces an approach to plan future water rates to achieve water distribution system (WDS) sustainability triple-top line (TTL) targets. The WDS components are modeled by connecting the EPANET hydraulic model with multiple interconnected subsystem models in a hybrid-system dynamics configuration. The approach is demonstrated with the hypothetical network, U-City, to optimally set the user fee to maximize a TTL sustainability index (SI). Overall, three demonstrations were performed to test the model: (1) identifying the influence of water price elasticity (WPE); (2) SI sensitivity to a water price adjustment in rate and time; and (3) optimal planning of a water price adjustment strategy. The first demonstration illustrated that neglecting WPE leads to an overestimation of revenue. The second demonstration confirmed that aggressive water pricing does not lead to increased SI. Finally, the third demonstration showed that frequent and lower water price increases are more favorable for a higher WPE to create a sustainable system. In summary, the proposed approach can provide a useful way to analyze future water rates to maximize the sustainability of a WDS.

Read the full paper in the ASCE Library: