The answer to 'why is my water heater burst pipe' is that a burst pipe on a water heater is often caused by a buildup of pressure or corrosion within the tank. This can happen if the temperature and pressure relief valve fails, the tank rusts through, or the tank is overfilled. Symptoms include leaking water, low water pressure, or a complete lack of hot water.
In many cases, a burst pipe on a water heater requires professional repair or replacement. Attempting to fix it yourself can be dangerous if you're not experienced with plumbing. It's best to call a licensed plumber to diagnose and repair the issue to ensure it's done safely and correctly.