Which of the following values represents a typical test pressure for water mains?

A typical test pressure for water mains is often set at 1.5 times the normal operating pressure. This value is used to ensure that the water main can withstand pressures that exceed normal operational conditions, allowing for a safety margin. During testing, the higher pressure helps to identify any potential weaknesses in the pipe or installation that could lead to failures when the system is in operation.

Engineers and regulators commonly adopt this standard to assess the integrity of the water distribution system, ensuring that it can operate safely under various conditions, including peak demand or emergencies. Thus, using 1.5 times the normal operating psi ensures that the system is robust enough to handle fluctuations and unexpected pressures without risk of failure or leaks.

The other options do not typically represent the standard testing pressure. Normal operating psi refers to the regular functioning pressure of the system. Testing at twice the normal operating psi could be overly stringent and potentially cause damage or stress on the infrastructure. Testing at half the normal operating psi would not adequately verify the system's ability to handle expected operational pressures, making it ineffective for assuring system integrity.