The answer to 'why is my water heater leaking water' is that there are several common causes for a leaking water heater, including a worn-out tank, loose connections, or a malfunctioning pressure relief valve. Symptoms may include water pooling around the base of the heater, dripping, or a sudden drop in water pressure.
In many cases, a leaking water heater can be repaired by a DIY homeowner, such as tightening connections or replacing the pressure relief valve. However, if the tank itself is cracked or corroded, it will likely need to be replaced by a professional HVAC technician. Attempting to repair a severely damaged tank yourself could be dangerous and lead to further damage or flooding.