Generally, the water pump is located at the front of the engine, driven by the engine's timing belt or serpentine belt. To be precise, you'll need to:
1. Identify your engine: Check your vehicle's documentation or the engine block itself for the engine displacement (e.g., 4.9L, 5.0L, 5.8L).
2. Consult a repair manual: A repair manual specific to your F-150's year and engine will show you exactly where the water pump is located, along with diagrams. You can find these online or at auto parts stores.
Without knowing the specific engine, giving a precise location is impossible.