The answer to 'water heater constantly running' is that the water heater is likely malfunctioning and running continuously, which can waste energy and increase utility bills. This can be caused by a faulty thermostat, a sediment buildup in the tank, or a problem with the heating element.
Some common symptoms include the tank feeling very hot to the touch, the heater kicking on and off frequently, and a higher than normal energy bill. If the water heater is constantly running, it's best to have a professional plumber diagnose and repair the issue to ensure it's working efficiently and safely.