Why is there a high pitched noise when water is turned on?

A high-pitched noise when water is turned on is often caused by the vibration of pipes due to water flow, a phenomenon known as "water hammer." This can occur when water pressure changes abruptly, causing the pipes to vibrate and produce sound. Additionally, the noise may result from air trapped in the Plumbing system or from the rapid movement of water through narrow or corroded pipes. If the noise is persistent or bothersome, it might indicate a need for plumbing adjustments or repairs.