A vehicle system includes a tank for storing an aqueous solution; and a UV light decontamination module configured for decontaminating aqueous solution stored in the tank. The UV light decontamination module is arranged in a wall of the tank. The UV light decontamination module includes a light source compartment which is accessible from an external area outside of the tank; and a light transmission member configured to transmit UV light from the light source compartment to a liquid space in fluid communication with aqueous solution stored in the tank. The light source compartment includes a light source to emit UV light through the light transmission member to the liquid space.