What are the signs of a water pump going bad on a 1999 Mazda millenia?

The water pump has one main seal, when the pump starts going bad the seal leaks and there is a slim line of coolant that flows downward due to gravity. If you suspect the pump find this line of coolant. When you see drops of antifreeze pooling underneath the car that is the first sign (do not confuse this with the normal water from the condenser(when you run the A/C) which is clear). Next you have to determine from where - easy to say, hard to do in practice. As soon as the coolant drops below a certain level the car will overheat and leak from everywhere. When coolant from the water pump leaks it will evaporate and leave a telltale residue that is easy to see with an experienced eye. This line of residue flowing downward from the main water pump bearing is the key. After the leak develops it will get worse till the bearing lubricant is washed out as well and then the bearing will seize. Once the pump seizes the belt driving the pump will break and you will be stuck.