Provided herein are tank-sensor systems and related manufacturing methods. In at least one aspect, the tank-sensor system includes a tank liner. The tank liner includes a body having a top end, a bottom end, an outer surface, and an inner surface. The tank liner also includes a recessed opening having a recessed portion and an opening. The recessed portion is positioned on the outer surface and the opening is positioned within the recessed portion and defines a through-hole between the outer surface and the inner surface. The tank-sensor system also includes a sensor inserted into the opening and engaging with the recessed portion, and a coating disposed around the outer surface of the tank liner and sealing the recessed opening.