LADWP Completes Pipe Installation After Century-Old Water Main Rupture in West Hollywood, but Broader Infrastructure Worries Persist

Los Angeles Department of Water and Power (LADWP) crews have finished installing a new 25-foot section of pipe in West Hollywood following a major rupture of a 110-year-old, 36-inch water transmission main beneath Sunset Boulevard earlier this week. The break, which occurred around July 16, 2026, sent water flooding streets on the Sunset Strip, disrupting traffic, businesses, and residents in the area.

The utility is now working around the clock to repressurize the line, test for leaks, disinfect it, and complete final repairs before reopening affected streets. No firm timeline has been given for full restoration, with Sunset Boulevard and nearby roads remaining closed as teams prioritize safety. The incident forced the removal of approximately 195,000 gallons of water from the site during excavation and replacement work.

This high-profile failure has spotlighted Los Angeles' aging water infrastructure. The ruptured line dated back over a century, and experts note that thousands of similar vintage pipes remain in service across the city. LADWP data shows the utility replaced only 11,500 feet of earthquake-resilient pipe in the 2024-25 fiscal year-short of its 17,600-foot goal-though it reports being on track for roughly 246,000 feet this year. Roughly 6% of the utility's distribution mains are flagged as high-priority for replacement.

Engineering specialists, including those from USC, warn that current replacement rates may not keep pace with the risks posed by the system's oldest sections, calling for accelerated funding and work to prevent future disruptions in a city where water mains over 100 years old are not uncommon. Residents and local officials continue to monitor the repair progress while expressing concerns about similar vulnerabilities elsewhere in Los Angeles.

LADWP prioritizes water pipe replacements using a risk-based asset management approach, outlined in its annual Water Infrastructure Plan.

The utility assesses roughly 6,794 miles of distribution mainlines (20 inches or smaller) and assigns priorities: about 6% high priority, 36% high-moderate, 41% moderate, 12% low-moderate, and 5% low. Trunk lines (larger transmission pipes) follow a similar process.

Key Prioritization Factors

LADWP evaluates multiple criteria for mainlines and trunk lines:

Leak history — Number, density, type of leaks, and time between failures.

Pipe age and material** — Older pipes (especially pre-1970s cast iron or those installed with outdated methods) and known failure-prone materials get higher priority. Over 30% of mainlines are more than 80 years old.

Soil and environmental conditions** — Corrosive soils, hillsides, landslide zones, fault lines, and liquefaction risk (critical in earthquake-prone LA).

Consequence of failure** — Risk of major service interruptions, community disruptions, flooding, or impacts to critical facilities.

Coordination opportunities** — Alignment with other city projects (e.g., Streets LA roadwork) to minimize repeated digging and costs.

Other system improvements** — Integration with broader reliability, seismic resilience, or regulatory projects.

They use desktop models and data from the Water Engineering and Technical Services Division’s Asset Management Group (including age, material, soil resistivity, pressure, and condition/leak data) to score assets and generate replacement lists. Final decisions for distribution mains are made by the Water Distribution Division; trunk lines involve additional planning input.

Goals and Approach

LADWP aims to replace 240,000 feet of mainline per fiscal year (a 150-year replacement cycle for the full system), focusing on earthquake-resistant ductile iron pipe (ERDIP) and welded steel where appropriate for seismic resilience. Projects often bundle replacements to improve overall system reliability and fire protection.

This system is data-driven but faces challenges: replacement rates sometimes lag targets, and experts note budget constraints limit faster progress on the large backlog of aging infrastructure. High-risk pipes (like the recent West Hollywood break) move to the front of the queue when leaks or other red flags appear.