A customer reports their sewer is plugged. What should you suggest first?

• A. Check their sewer main
• B. Check their manhole
• C. check their service line/is their service line working
• D. Check customer water meter

Answer: (C)

When a sewer backup is reported, the first thing to check is the service line—the boundary between the customer's property and the sewer system. The service line carries wastewater from the building to the sewer main, so testing it quickly tells you whether the problem is on the customer’s side or farther out.

If the service line is functioning (water and wastewater move normally when fixtures are used), the blockage is likely downstream of that point—in the sewer main or public lateral—and the utility should address it. If the service line is blocked or backing up, the issue is on the customer’s side and may require the customer to clear the line or call a plumber.

Choosing to check the sewer main, a manhole, or the water meter isn’t the best first step because they don’t immediately indicate where the blockage lies relative to the customer’s property.