What does the standard water leak test measure in gravity sewers?

• A. Gallons per inch diameter per mile
• B. Gallons per hour
• C. Gallons per day
• D. Gallons per foot

Answer: (A)

The test is designed to quantify how much water a gravity sewer leaks in a way that can be compared across different pipe sizes and lengths. Leakage isn’t just about how much water is lost overall; it tends to scale with both the length of pipe and the pipe’s diameter. That’s why the standard measure uses gallons per inch of diameter per mile of pipe. By taking the daily water loss and dividing by the miles of pipe and the pipe diameter in inches, you get a normalized leakage rate that can be compared from one project to another regardless of how big or long the sewer segment is. This is more meaningful than just gallons per hour or gallons per day, which don’t account for how much pipe and what size is being tested.