The longest a 2 in. water main can run is how many feet?

• A. 1,200 ft
• B. 1,000 ft
• C. 900 ft
• D. 1,100 ft

Answer: (B)

In water distribution, the distance a main can run is limited by pressure losses that accumulate as water flows through the pipe. A smaller diameter pipe like a 2-inch main has higher friction loss per foot, so to keep the far end above the minimum required pressure, designers cap the run length. For a 2-inch main, that maximum practical run is about 1,000 feet. So the longest distance that can be reliably served is 1,000 feet. Going longer would likely drop pressure too low, and longer runs would require using a larger pipe or adding pumping/boosting or looping to maintain adequate pressure. The other options either exceed this typical limit or fall short of the maximum allowable length.