The interrogatory itself is ridiculous as it contains the answer within the question: Of course, drinking "too much" water is bad. Doing anything "too much" is bad.
In fact, drinking "too much" water can disrupt one's electrolyte balance. Drinking "too much" water can even cause death.
Conversely, drinking "too little" water is also bad, as dehydration is quite serious and probably easier to have happen than the consequences of drinking "too much." One needs to monitor one's intake of water with the ambient conditions in which one finds oneself: If you are exercising, working, playing in extremely hot temperatures, one should regularly be hydrating. If the temperatures are moderate or cold, one does not need to drink as much as doing the same activities in hot weather.
Particularly in hot weather, however, one is advised to drink before one becomes thirsty, as the overheating can overtake the body's abilities to rehydrate. When the weather is cold, probably waiting until one feels thirsty is much less critical. Certainly, when in hot climates, one should definitely rehydrate as soon as one realizes one is feeling "thirsty," as that does mean one is already on the road to dehydration. In hot climates, one should be consuming liquids at least in relative balance with one's loss of water. (One visual indicator is the color of one's urine -- a darker color yellow in hot weather indicates at least some minimal dehydration if not greater.)