The reason you see water when you run the a/c system is because the evaporator is removing the moisture in the air from inside the vehicle. you see it is hard to cool moist air. The apposite is true in your home that is you can't heat dry air.
Leaks water? The condensation drain is plugged.
If your car will not hold water you should first check your radiator for holes and leaks. This should be done with the engine turned off. If you do not find any leaks coming from the radiator and the water stays inside, turn on your vehicle and let it idle. If you notice water leaking from the vehicle while it is running, then your water pump is bad and will need to be replaced.
Need to replace the water pump.
water pump
If by water you mean engine coolant, yes. Loss of coolant, antifreeze, is a major cause of overheating.
It is not so much the temperature of the water but the pressure that the hot water produces. If you will look at almost any car radiator cap you will notice a warning that says something to the effect'warning contents under pressure. Do not remove when hot.'
Look at it to see if there are leaks coming from it, and check it to see if it pumps fluid.
It could just be that the water pump is not properly working. Have you checked all the could-be causes for your car overheating if not then do so.
Take it to a mechanic. Have them check for leaks.
Probably low on refrigerant. Have it checked for leaks, repair if necessary and recharge.
Typically the water pump will make noise or show residue from leaks from the water pump bracket. You could also use a special tool that puts about 10-14psi of pressure on the cooling system and raise the car and see if it leaks from the water pump.
first turn on the car and add the water to the radiator while the engine is running-- this allows the water pump to work and force the water to all the thirsty parts this will help the radiator and the crankcase fill much faster