Model calculations to investigate the deuteron quadrupolar relaxation in liquid water are performed. Techniques not amenable to experiment, such as switching on and off the intermolecular or intramolecular electric field gradients and simulating rigid liquid water, give insight into the microscopic effects leading to relaxation. In experimental studies it is usually assumed that the deuteron quadrupolar relaxation is governed largely by the reorientational motion of an average electric field gradient, and the error in this assumption is readily extracted from the model calculations. As expected, this error is significant for deuterons in hydrogen bonds. These model calculations should provide a guide to better understanding of quadrupolar relaxation and experimental evaluation of relaxation. (C) 2003 American Institute of Physics.