To optimize the process performances, the Aquasource UF membrane, which is widely used for potable water production, can be operated in both dead-end and cross-flow filtration mode due to its hollow fiber membrane configuration. A pilot study was undertaken to evaluate the UF process in dead-end filtration compared to cross-flow filtration mode in terms of water loss, energy consumption (flux rate achievable:). The study performed on surface water, i.e., high variable water quality, has shown that the membrane specific flux in cross-flow filtration seems to be more stable at high flux, i.e., 100 L/h.m(2). However, results have shown that in dead-end filtration, a gain of about 0.3 kWh/m(3) is realized on energetic balance. In this case, the energy consumption is around 0.2 kWh/m(3) and represents only a small percentage of the operation and maintenance costs. However, maximum flux achievable needs to be tested for both operating modes in order to evaluate the capital cost in terms of membrane surface requirement.