In some embodiments, a system for pre-wetting a filter includes a filter, a piping system, a first gas, a second gas, a first buffer tank, and a second buffer tank. The first gas drives the solvent to clean the filter. The two buffer tanks store the solvent discharged from the filter. The second gas selectively drives the solvent in the first buffer tank to return to the filter and then to be discharged into the second buffer tank. Alternatively, the second gas selectively drives the solvent in the second buffer tank to return to the filter and then to be discharged into the first buffer tank.