Why is my water heater overflowing and what should I do to address this issue?

Your water heater may be overflowing due to a buildup of pressure or a faulty pressure relief valve. To address this issue, you should first turn off the power or gas supply to the water heater. Next, try releasing some of the pressure by opening the pressure relief valve. If the problem persists, you may need to contact a professional plumber to inspect and repair the water heater.