My car is overheating and leaking water.
Coolant system leaks completely disable the the engine cooling system from properly cooling the engine. This can cause serious engine damage if not addressed. The problem with some of these leaks, they are not detectable unless the cooling system is placed under pressure. Often times, as engine coolant leaks it will leave a white residue or even moisture in the area where the leak is occurring.
One important note: NEVER remove the radiator cap on a hot engine, even with a leak, the system could still have pressure and you could get serious injury by removing the radiator cap.
Once the suspect component or hose is identified replacing the component and its associated seal or gasket will remedy both the leak and the overheating. You may want to enlist the help of a mechanic, like one from YourMechanic, who will be able to pressurize the cooling system to identify where the leak is coming from. Then safely make the appropriate repair and pressure test the system again afterwards in order to verify that no other leaks exist. This cooling system upon refilling it has a bleeding procedure that must be followed in order to ensure all air is purged from the cooling system. Without bleeding the system, overheating can still occur even though the leak was repaired. A qualified technician will be able to properly fill and bleed your cooling system to ensure the cooling system works to optimum performance.