Ya probably its in fuel tank or below the tank.
Well, changing fuel filter beyond 40k depends on the quality of fuel available. It is the responsibility of the fuel filter to trap large particles in the fuel in order to prevent them from getting into the engine. Any large particles in the fuel could potentially cause damage to the engine. Large particles in the fuel also have the ability to clog fuel injectors, requiring that the injector be cleaned or replaced. Therefore, maintaining a clean fuel filter is imperative to the performance of a car's engine.
Keeping in mind the bad quality of fuel available here, i suggest to change it as per recommended time lines.