A reductant storage system for an internal combustion engine system includes a storage container having a bottom wall, a top wall opposite the bottom wall, an opening extending through the top wall, and a reservoir formed by a hollow interior of the storage container and a filter assembly. The filter assembly extends through the opening and include a filtering material and a gasket integrally formed with the filtering material. The gasket includes a proximal flange that is larger than the opening and including a sealing surface in sealing contact with the storage container.