Start with the pattern
One slow fixture may be a local clog. Several slow drains, sewage at the lowest drain, or repeat backups point more strongly to the building drain or sewer lateral.
When several nearby properties are affected, the public sewer system may also need to be checked.
The next step should locate the problem
The first evaluation should establish where flow is blocked, what is known and still unknown, and whether cleaning, camera inspection, focused repair, replacement, or public-system follow-up fits.
What an estimate should include
The written scope should identify the defect, location, affected footage, pipe material, access, permits, restoration, exclusions, and the conditions that could change the method or price.
Sources
- Minnesota 811 / Gopher State One Call — State utility-location requirements before excavation.
- NASSCO PACP condition grading — Sewer inspection condition categories.