Water Resource degradation coupled with more stringent water quality regulations have promoted an increasing use of low pressure membrane processes: Microfiltration (MF) and Ultrafiltration (UF). Both MF and UF are effective at removing particulate material from water such as Giardia and Cryptosporidium cysts bacteria. In addition, UF process, due to its tighter cutoff, will also remove viruses. These processes present other operational advantages to treatment of drinking water such as limited use of chemicals, smaller space requirements, and lower operation requirements. However, membrane filtration performances are highly depencent on the raw water quality. 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. It should be noted that the energy consumption varies with the filtration mode adopted. Thus, the goal of this pilot study was to evaluate the UF process in dead-end filtration compared to cross-flow filtration mode, in terms of water loss and energy consumption. Includes tables, figures.