Which part of a gas water heater contains the hottest water?

The top quarter of a gas water heater contains the hottest water due to the principle of convection. When water is heated, it becomes less dense and rises to the top of the tank. As the water heats up, it moves from the bottom section, where the burner heats the water, to the top section. The hot water is drawn from the top for use in the household, which ensures that the area where the hot water is most concentrated is at the top of the tank.

The design of water heaters leverages this behavior of heated water to maximize efficiency and provide a ready supply of hot water. Additionally, any water that goes cold at the top can be pushed down into the tank for reheating by the new incoming cold water, thus maintaining a continuous cycle. This mechanism ensures that the hottest water will consistently be present in the top quarter of the tank.