Regionalization
ALCOSAN is taking ownership of municipal trunk sewers to streamline system-wide performance.
Connect Communities
Clean Water Plan
Turning the Tide – Together
ALCOSAN’s Clean Water Plan will help reduce wastewater overflows that impact the water quality of our region’s waterways. We’re tackling this issue head-on by expanding plant capacity, building nearly 18 miles of tunnels below our rivers, and partnering across the region to protect our rivers, streams, and communities.
See the PlanClean Water Plan initiatives
Plant Expansion
Northside facility expansion will increase treatment capacity and reduce overflows.
Explore Upgraded Capacity
Regional Tunnel System
Capturing more wastewater during wet weather to help protect regional waterways.
Explore the Tunnel System
GROW / Source Control
ALCOSAN’s GROW grants reduce excess flow from stormwater and groundwater infiltration.
Learn About GROW GrantsClean Water Plan Construction Timeline
2025–2029
Construction of the Ohio River Tunnel and related infrastructure
2028–2034
Construction of the Allegheny River Tunnel and related infrastructure
2029
Completion of plant expansion projects
2030–2036
Construction of the Monongahela River Tunnel and related infrastructure
2036
Completion of the Clean Water Plan (initial goals)
Regionalization
Regionalization will more than double ALCOSAN’s sewer system ownership and maintenance responsibilities across the region.
265Miles of Sewer
8Wet Weather Facilities
77Diversion Structures
Learn how ALCOSAN is working with municipalities to take ownership of trunk sewers and related facilities to create a more streamlined regional system.
Discover the Regional Strategy
Plant Expansion
As part of the Clean Water Plan, ALCOSAN’s Northside facility is expanding—increasing treatment capacity and reducing overflows from excess stormwater.
These critical upgrades will help manage peak wet-weather flows and ensure compliance with federal clean-water standards for years to come.
Explore Our Upgraded Capacity
Regional Tunnel System
ALCOSAN is building a new Regional Tunnel System to capture combined wastewater during wet weather and convey it to the wastewater treatment plant.
The system will include three major tunnel projects along the Ohio, Allegheny, and Monongahela rivers. Working together, the tunnels and related facilities will provide additional capacity, reduce wastewater overflows, and help protect the region’s rivers and streams.
GROW / Source Control
ALCOSAN’s Green Revitalization of Our Waterways (GROW) program reduces excess stormwater and groundwater entering an overloaded sewer system—helping prevent overflow events at the source.
With continued investment and collaboration, the GROW program is delivering measurable impact across the region.
Explore the GROW Program
190
Active or completed GROW projects
210+ million
Gallons of overflow reduction
Resources
Clean Water Plan Overview
Download a summary of ALCOSAN’s long-term strategy to reduce sewer overflows and protect our waterways.
Download Clean Water Plan Overview PDF (opens in a new window)GROW Program Grants
Learn how municipalities can apply for GROW funding to reduce wet-weather impacts.
Explore Now!Regional Tunel System
Explore key facts, timelines, and benefits of ALCOSAN’s tunnel infrastructure investment.
Dig in! aite (opens in a new window)Sewer Overflows
A combined sewer overflow occurs when stormwater and diluted sewage overload the sewer system and flow into rivers and streams.
Read More