Drive 4-5 km till the temprature goes up and then pop ur hood open. If the radiator cap is busted chances are you will see steam coming out of it.
Ditch water, use a good coolant. Raises the boiling point of water, hence letting the water cool the car more. Get the radiator serviced. Make sure the fans are working fine when the AC is on (both turning on or not, as well as if fast enough). Change pipes, could have a leak.
The last time I faced a similar problem, radiator cap was the culprit ... as the hot water came back from the engine ... it evaporated rather quickly.
Also get the thermostat valve checked.
Thats pretty much all the stuff that could generally go wrong. Get good coolant, Caltex one is expensive but works like a charm. 50/50 ratio of water and coolant.
