ALCOSAN Started Massive Pittsburgh Sewer Project
The $4.5 billion initiative aims to drastically reduce sewage overflows into regional rivers.
Updated on Oct. 8, 2026 in Home Renovation
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ALCOSAN has launched a massive infrastructure project to construct 15 miles of underground tunnels beneath Pittsburgh. The work is designed to capture overflow from the city’s antiquated sewer system during wet weather.
Why it matters
The project addresses a critical environmental challenge, as approximately 9 billion gallons of sewage-laced water currently overflow into local rivers and streams annually. These tunnels are expected to reduce that discharge by 7 billion gallons each year.
The $4.5 billion Clean Water project features a 15-mile tunnel network and a treatment plant expansion. Annual customer bills have risen from $381 in 2019 to $612 today, reflecting a consistent 7% yearly increase.
The players
ALCOSAN
The Allegheny County Sanitary Authority manages the wastewater treatment system for Pittsburgh and dozens of surrounding municipalities.
The details
A giant boring machine will excavate the new system deep under three rivers to manage sanitary and storm water capacity. Construction will involve the creation of riverfront access sites, where the community will be subject to acoustic barriers and blasting alerts.
Timeline
Annual 7% sewage bill increases began in 2019.
Construction on the tunnel project begins in October 2026.
The authority expects to announce a higher rate increase within the next month and a half.
Construction work is scheduled to last for 6.5 years.
Roadmap
This project represents a major capital investment required to modernize aging municipal infrastructure. It follows a cost-overrun pattern set by the Ohio River Tunnel phase, which exceeded its original estimate by $200 million.
Residents should anticipate ongoing construction noise and potential blasting alerts near riverfront access sites throughout the 6.5-year timeline. Households will likely face further annual bill increases as the authority works to finance the $4.5 billion project.
The takeaway
Large-scale utility projects often face significant budgetary pressure as they progress through long construction windows. Residents should prepare for higher service costs as infrastructure upgrades continue to scale.
What happens next
ALCOSAN is expected to announce a new rate increase for customers within the next month and a half.
Further reading
Learn more about local infrastructure updates on the Home Renovation section page.
Source note: This article includes information reported by CBS News.
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