What is the minimum clearance required between the bottom of a water line crossing above a sewer and the crown of the sewer?

What is the minimum clearance required between the bottom of a water line crossing above a sewer and the crown of the sewer?

• A. 18 inches
• B. 10 feet
• C. 24 inches
• D. 3 feet

Answer: (A)

When a water line crosses above a sewer, you need a vertical separation to protect the potable water system from sewer surges or backflow and to allow space for maintenance. The bottom of the water line must be at least 18 inches above the crown of the sewer. This distance helps minimize the chance that wastewater could reach the water line during surcharges and provides room for inspection and repair work. Larger clearances are permissible in some situations, but 18 inches is the minimum standard to remember.

When a water line crosses above a sewer, you need a vertical separation to protect the potable water system from sewer surges or backflow and to allow space for maintenance. The bottom of the water line must be at least 18 inches above the crown of the sewer. This distance helps minimize the chance that wastewater could reach the water line during surcharges and provides room for inspection and repair work. Larger clearances are permissible in some situations, but 18 inches is the minimum standard to remember.