My car's brake seems to having some problems. Before Whenever I brake, I only use around 20 - 40% of the brakes(I kinda half step through the brake pedal) and the brakes seem to work instantaneously. But ever since I drove the car through a flood(the water was just around a centimeter below the car's ground clearance), My car does not respond that well when I brake lightly, instead I have to brake at around 70 - 90% just so the car would brake immediately. I have tried cleaning the rear brakes(drum brakes), but I am still experiencing a lot of brake fade. Is there a way I could adjust the brake response? Or do I also have to check my front brakes? I had just replaced my rear brake pads around 3-4 months ago, and I've just done around 1.5k ever since the replacement. Are tires also a factor as well?
Having the rear shoes adjusted will help with the pedal travel issue. Another possibility is that the brakes, both front and rear were contaminated by something in the water. It could have been oil, silt, mud etc. This may have glazed the brake material leaving a hard smooth surface that doesn't generate a lot of braking friction. You can try to remove the rear drums and spray the shoes and interior of the drums with quality brake specific cleaner. It wouldn't hurt to rough the shoes up with some sandpaper to breakup any glazing that may have occurred. I would do the same with the front pads and rotors as well.