How much water will pass through a 4 pipe at normal atmospheric pressure?

The flow rate of water through a 4-inch pipe at normal atmospheric pressure depends on various factors such as the pipe's length, the presence of bends or fittings, and the pressure differential. Generally, a 4-inch diameter pipe can carry approximately 1,000 to 2,000 gallons per minute (GPM) under ideal conditions. However, actual flow rates may vary based on the specific application and system design. To determine the precise flow rate, you would need to consider the system's specific parameters and use fluid dynamics equations.