City of Boulder Utilities runs the public sewer, and replacing your sewer line means new pipe for the private section from your house to that system. It usually comes up when an older line has broken or filled with roots in several places. Call the number on this page to be connected with a local plumber in Boulder.

Signs a repair won't hold
- The main line needs rodding or jetting again and again
- Water rises in a basement shower or floor drain when a toilet flushes
- Drains across the house slow down together
- Sewage odor outdoors, or a damp patch along the line's route
- Camera footage of offset joints, cracks or roots at more than one spot
A single defect is often worth fixing in place. When the damage is spread from the foundation to the street, a full new line usually costs less over time than repeated repairs.
Boulder's sewer and building rules
City wastewater is treated at the Boulder Water Resource Recovery Facility, which returns treated water to Boulder Creek. For sewer maintenance problems and after-hours calls, the city's line is 303-441-3200. If several houses on your street are affected, start there; a backup that stays inside your house usually points to the private line.
Boulder's Planning and Development Services draws a useful line on permits. Minor work such as clearing a drain stoppage or repairing a leak is exempt, but replacing concealed drain or supply piping counts as new work and needs a permit. A sewer line replacement falls on the permit side. Plumbing is a single-trade permit, and P&DS is at 1101 Arapahoe Avenue, 303-441-1880.
Boulder's older neighborhoods near downtown and the university are the likelier places to find original clay or cast iron drain pipe, while homes from later decades usually have plastic. Owners of pre-1956 homes are already encouraged to check their water service line material on the city's map, and a sewer camera inspection does the same job for the drain side.
What changes the cost
- Distance and depth from the foundation to the city's sewer
- Trench or trenchless, depending on whether the old pipe still holds its slope
- Mature trees, stone walls and patios along the route
- Interior drain pipe that may be worn out too
- Permit and inspection through P&DS
After you call
You'll be connected with an independent local plumber who works in Boulder. A camera inspection usually comes first, since the method and price depend on the pipe material, how deep it runs and where it has failed. The plumber will typically handle the single-trade permit and schedule the inspection before the trench is backfilled.
Sewer Line Replacement questions in Boulder
Who issues the permit for a sewer line replacement here?
Should I call the utility or a plumber first when sewage backs up?
What were older sewer service lines around here usually made of?
Can sewer line replacement be done in a Colorado winter?
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