Why is a surge tank essential in a water supply system?

A surge tank is essential in a water supply system primarily because it helps minimize water hammer. Water hammer is a pressure surge that occurs when a fluid in motion is forced to stop or change direction suddenly. This phenomenon can lead to significant damage within pipelines, such as ruptures or leaks, and can affect valves and machinery connected to the system.

By providing a cushion of air or a volume of water that can absorb sudden pressure changes, the surge tank mitigates these pressure spikes. This not only helps in maintaining the integrity of the system but also ensures smoother operational conditions, which can enhance the overall efficiency and longevity of the water supply infrastructure.

The other options—such as the function of storing large volumes of water, increasing pressure, or reducing water contamination—are important aspects of water systems but do not specifically address the primary role of a surge tank. Surge tanks are designed specifically to manage transient pressures and protect the system from hydraulic shocks, making their role crucial in ensuring the reliability and safety of water supply systems.