In multi-level wave energy converters, water from incoming waves is stored in reservoirs one on top of the other. Prevision formula for the overtopping flow rates in the individual reservoirs is fundamental for dimensioning correctly the turbines and optimizing the device. A study was carried out to describe the dependence of the overtopping on a new parameter, i.e., the horizontal distance (HD) between the reservoirs. The overtopping in the lower reservoir increased with increasing HD. Overtopping in the upper reservoir decreased with increasing HD. A threshold after which the parameter HD may increase or decrease the overall efficiency of the device exists. Two different formulations of the overtopping prediction formula by Kofoed 2002 were derived, which can account for the HD parameter. This is an abstract of a paper presented at the 2009 International Offshore and Polar Engineering Conference (Osaka, Japan 6/21-26/2009).