Couple of things to check - overheating and using water can be because the head gasket has gone and this causes the water to go into the engine. The way to check is to have a look at your oil dipstick - if it has greyish deposits then water has got through. It requires the top of the engine to be taken apart and a new gasket to be fitted.
Overheating can also be a faulty thermostat which works by letting more water go through the system as the engine warms up - if faulty it does not let enough water into the engine and it overheats. This is the cheapest fault - lets hope it is this one!
simon pearson
July 2010