A well-calibrated model of a water distribution network is necessary for monitoring, control, and operation. In this work, we address the problem of parameter estimation in water distribution networks (WDNs). Typical parameters to be estimated include the coefficients used to model major (pipes) and minor (joints, etc.) losses due to friction. The problem of parameter estimation is a nonlinear regression problem and is solved using the error-in-variables approach. The method is illustrated using data from an experimental facility.