The city is implementing a program to rehabilitate its clay sewer pipes.

The City of Boulder's sanitary sewer system consists of underground pipelines used to collect and transport untreated wastewater to the city's wastewater treatment facility. A large portion of the city’s sanitary sewer system was constructed in the 1940s through 1960s when it was common to construct sewers using clay pipes. These sewer pipes are now beginning to reach the end of their useful life.

Know if Your Sewer is Being Rehabilitated

Written notice

The City of Boulder will mail you a letter at the beginning of the year your line is scheduled to be rehabilitated. The city's contractor, Eco-Matrix, will then contact you three times to notify you of the work status:

  • 24 hours in advance of the start of the work by direct contact at your door (if you are not at home, Eco-Matrix will leave the attached sample door hanger on your front door)
  • Immediately before work begins (STOP using indoor water at this point, you may drink tap water during work)
  • After your sewer service has been reinstated (okay to use water after this)

If you have received a notice

Do not use indoor water while work is being conducted (exception: you may drink tap water during this time). The city's contractor, Eco-Matrix, will notify you 24 hours in advance of when work is scheduled to begin and will also notify you when work is completed and sewer service has been reinstated.

You may use water for outdoor use while the sewer maintenance is being conducted.

Traffic and parking

Traffic and on-street parking may be temporarily disrupted in the work area. If parking restrictions are needed, the city will post “no parking” signs 72 hours in advance of the work. After posting no-parking signs, the city may relocate or tow vehicles if they are interfering with work areas.

Frequently Asked Questions

The sewer rehabilitation process involves placing a liner into the sewer, inflating it to fit the shape of the existing sewer and then hardening it into a new solid pipe inside of the existing one. The process costs about a quarter of the traditional approach of excavating and replacing the old pipes with new ones, and it takes about half a day, instead of multiple days, to complete.

Do not dispose of any water via your indoor plumbing during construction. This includes most indoor plumbing fixtures such as toilets, sinks, bathtubs, showers, dishwashers, washing machines, floor drains, etc.

Do not use any more water. Although your sewer service is blocked during the liner installation, there is typically sufficient storage in the service to accommodate accidental toilet flushing or hand-washing without causing a backup. If you used a lot of water, such as by taking a shower or running the dishwasher, check the floor drains or bathroom on your home’s lowest level for signs of a backup.

If you have concerns regarding tenants using water during the installation process, please contact the Utilities Division at 303-441-3200. Arrangements can be made to shut off the water supply to the building during the installation process.

Homeowners are responsible for their sewer services from the home all the way to and including the connection to the city main in the street. The city’s work only rehabilitates the city’s main sewers and will not impact or address any issues with your home’s sewer service. Local plumbing companies can use the same lining technology the city uses, which can represent a significantly cheaper alternative to replacing sewer service.

The city continuously inspects its sewer system for structural defects using a robotic camera. Approximately 70% of Boulder’s sanitary sewers were constructed in the post-World War II period using clay pipes. Over time, factors such as shifting soils or heavy traffic loads can cause these clay pipes to develop cracks and defects. The last inspection showed that the sewer serving your building had sufficient structural defects to warrant installation of a liner.

The Utility Division’s Sanitary Sewer Rehabilitation Program is funded by wastewater use rates paid by Boulder residents and businesses. In 2014, City Council approved a 30 percent wastewater rate increase to expedite rehabilitating the city’s aging sewer infrastructure. This additional funding will allow the city to rehabilitate or replace its clay sewers over a 20-year period versus the 100-year period allowed by previous funding levels.

The rehabilitation work is completed using a unique trenchless technology that does not require any excavation.

  • Step 1: Cleaning - Crews clean the pipe with a high-pressure jet hose and remove any debris that has accumulated in the line. Debris is then vacuumed out of the system and taken to a landfill.
  • Step 2: Inspection - Crews use a robotic CCTV camera to inspect the line and identify if it is ready for the liner to be installed. This process also identifies the location of all service connections on the line so they can be reinstated after the liner is in place.
  • Step 3: Bypass Pumping - The process requires that the sewer main be dry, so crews use bypass pumps to allow users upstream to remain in service. Bypass pumps are set at manholes upstream and discharge further downstream from the main being rehabilitated.
  • Step 4: Liner installation - A spool of PVC pipe is warmed up, making it malleable enough to pull into the old sewer main, or “host pipe”. The pipe is then blown up with compressed air to fit tightly inside the host pipe. Once the new line has cooled, it is a fully structural “pipe in a pipe”. The installed liner is then checked for defects with a camera prior to reinstating service connections.
  • Step 5: Service Reinstatement - After the pipe has cooled and inspected, a robotic cutter is placed into the main and driven to the location of each service connection. This cutter opens a hole in the same location of the original tap, allowing the service line to return to operation.
  • Step 6. Final Inspection - Following the tap reinstatement, the newly lined pipe is inspected with a CCTV camera and documented to verify the quality of the installation and provide a record of the completed product.

Report Sewer Backup or Maintenance


In the event of a sewer backup on your property, the city will respond and determine the cause of the backup and assist if possible. Sewer customers should be aware that the sanitary sewer service line is the responsibility of the property owner up to and including the connection to the city-owned sewer main. If the problem is determined to be in the sewer service line, it is recommend that you call a plumber to investigate and resolve the problem.


After hours staff respond to true emergency events, such as sewer backups, overflows and missing manhole covers.

Please report all emergency issues by phone (do NOT make an online service request) to ensure a prioritized response by city staff.

  • Emergency / After-hours Emergency

Utility Locates

Do NOT use Inquire Boulder to request utility locates prior to digging.