A filtration assembly structured to filter reductant includes an outer housing and an inner housing. The inner housing is positioned within the outer housing. The inner housing is structured to contain the reductant and operable between a first state in which the inner housing has a first volume and a second state in which the inner housing has a second volume that is larger than the first volume, the inner housing including an end face. The inner housing is separated from the outer housing by a gap when the inner housing is in the first state. A volume of the gap decreases as the inner housing transitions from the first state to the second state and increases as the inner housing transitions from the second state to the first state.