Pipeline Relining

About This Project

The San Diego County Water Authority’s pipelines extend approximately 310 miles to convey water throughout San Diego County. Approximately 82 miles of the pipelines are pre-stressed concrete cylinder pipes (PCCP). These types of pipes were installed between the early 1960s and the late 1980s, servicing many large diameter water distribution systems throughout the world.

Made from a combination of steel and concrete, PCCP is used extensively around the world. It was first used during World War II to help minimize the use of steel, appearing highly resistant to corrosion and able to provide unparalleled inner pipe strength. However, numerous catastrophic failures have occurred with these pipes worldwide. In response, the Water Authority instituted a pro-active 30-year pipeline relining program in 1991 to reinforce the pipes with steel liners. In addition, in 2003 the Water Authority began utilizing an innovative technology, using carbon fiber, to conduct urgent pipeline repairs, helping ensure a safe and reliable water supply to the region.

For an overview of the relining process, watch this video:



Pipeline Relining

Pipeline relining is used on long stretches of pipelines and involves inserting new steel liners into an existing pipeline. The new liners, which serve as new pipelines, are anticipated to last approximately 50 to 75 years. Relining the existing pipelines with steel is a quicker, more cost-effective alternative to excavating, removing, and replacing an entire pipeline and generally takes up to a year to complete. To date, the Water Authority has relined nearly 41 miles of PCCP within its service area and is anticipating rehabilitating the approximately 41 remaining miles of PCCP by 2027.


Urgent Carbon Fiber Repairs

Carbon fiber is a synthetic fiber originally developed in the early 1960’s for use in the aerospace industry. Because of its light weight, strength, and speed and ease of installation, it is used in small sections of pipes that are in need of urgent repairs. While currently not as cost-effective as using steel liners to reline longer sections of pipelines, carbon fiber wraps are adhered to the interior of a pipe’s wall, fortifying the pipe and allowing it to quickly be put back into service. Most urgent carbon fiber repairs can be completed within days.

While most relining work is conducted inside the pipe, minimal impacts to the immediate community can occur. In all cases, the Water Authority continuously works to minimize impacts to nearby residents, including noise, dust, traffic and limited access near work sites. When work is complete, areas impacted by construction are restored to their original condition or better.


Current Pipeline Relining Projects

Fallbrook Pipeline Relining Project (Pipeline 5)


Future Pipeline Relining Projects



Completed Pipeline Relining Projects

• Paint Mountain to Del Dios Highway Relining Project (Pipeline 4)
• Del Dios Relining Project (Pipeline 4)
• Mission Trails to Lake Murray Relining Project (Pipeline 3)
Pomerado Relining Project (Pipeline 4)
• Rancho Peñasquitos / Mira Mesa Relining Project (Pipelines 3 & 4)
• Relining Under I-15 Project (Pipelines 3, 4, & 4A)

Miramar Hill to Scripps Ranch Relining Project (Pipelines 3 & 4)
• Mission Trails to Lake Murray Relining Project (Pipelines 3 & 4)
• Sweetwater to Lower Otay Relining Project (Pipeline 4)
• San Luis Rey Relining Project (Pipelines 3, 4, & 5)
• Lake Murray Pipeline Relining Project (Pipeline 3)
• Lake Murray to Sweetwater Reservoir Relining Project (Pipeline 3)



Visit the multimedia section below to view images of past relining projects.


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Visit the individual relining project web pages to view the schedule for each project. 

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Visit the individual relining project web pages to view a map for each project.

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The portal area is graded and prepared for excavation.

Overview of portal area with sound walls and fencing installed.

Pipe is excavated and broken in preparation for removal.

Large diameter pipe is delivered to the site on large flatbed trucks.

Welders fuse the pipe together inside the trench.

Each segment of pipe is welded together, forming the new pipeline.

Large trucks mix the grout onsite in preparation for securing the new pipe to the existing pipe.

Grout is delivered into the trench using a scaffolding system.

A final section of pipe is put into place.

The entire pipe is encased in concrete and rebar prior to refilling the portal.

Interior of the pipe after the mortar lining is completed; it is now ready for disinfection and water flow.


Pipeline Relining Overview Video

This video below provides an overview of the San Diego County Water Authority’s Pipeline Relining Program.

News Stories About Pipeline Relining Projects

This video summarizes a recently completed project near Mission Trails Regional Park.

News Stories About Urgent Carbon Fiber Repair Projects

This news story describes an Urgent Carbon Fiber Repair Project conducted in Fallbrook, California.

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Visit the individual relining project web pages to view publications for each project.

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Visit the individual relining project web pages to view the community outreach conducted for each project.

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Visit the individual relining project web pages to view  to view the reports and other environmental documents for each project.

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For more information about the Water Authority’s Pipeline Relining program, please call the 24-hour toll-free project information line at (877) 682-9283, ext. 7005 or email CIPinfo@sdcwa.org. A representative from the project team will return your inquiry within one business day.

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