Describe the function of an overflow pipe in water tanks.

The function of an overflow pipe in water tanks is primarily to prevent overfilling. When the water level in the tank rises to a certain point, the overflow pipe allows excess water to escape, thereby ensuring that the tank does not spill over or exceed its capacity. This mechanism is critical in maintaining safe operating levels and preventing potential water damage or structural issues caused by overflows.

Moreover, the overflow pipe can help avert problems related to water stagnation and contamination, as the discharge of excess water can help to maintain a fresher supply within the tank. Every tank design includes an overflow system to ensure it operates efficiently and safely under various conditions.

While other options present functions related to water management, they do not specifically relate to the purpose of the overflow pipe. For instance, adding more water or measuring water levels are not functions of the overflow pipe; instead, these would involve different mechanisms or components such as filling systems or level sensors. Circulating water within the tank is also not the role of an overflow pipe, which focuses solely on handling excess water.