Curb Stops vs. Corp Stops: What’s the Difference in Water Main Projects?

Understanding where and why each valve is used helps contractors avoid rework, failed inspections, and future service calls.

When it comes to water main construction and service connections, few components are as misunderstood—or as critical—as curb stops and corporation stops. While both play essential roles in controlling water flow to properties, they serve very different functions, are installed at different locations, and are governed by distinct municipal standards.

For Illinois water contractors, knowing when to specify a curb stop versus a corporation stop is not just good practice—it’s required for compliance, inspection approval, and long-term system reliability.

This article breaks down:

• What each valve does

• Where each is installed

• How municipalities typically regulate them

• Common mistakes contractors make

• Best practices for sourcing and installation

What Is a Corp Stop?

A corp stop is a small shut-off valve installed directly into the water main. It serves as the connection point between the municipal main and the individual service line.

Key Characteristics of Corporation Stops

• Installed directly into the water main

• Controls water flow from the main to the service line

• Typically threaded or compression-style

• Common sizes: ¾″, 1″, 1¼″, 1½″

• Usually operated only by the municipality

Typical Installation Location

• Tapped into the water main (cast iron, ductile iron, PVC, or HDPE)

• Below grade

• Not accessible from the surface after installation

Primary Purpose

The corporation stop allows:

• Initial connection of the service line

• Isolation of a single service without shutting down the main

• Municipal control over individual connections

In most jurisdictions, corp stops are owned and controlled by the water authority, not the property owner.

What Is a Curb Stop?

A curb stop (also called a curb valve or service shut-off) is installed on the service line between the water main and the building. Its purpose is to allow the water supply to a specific property to be shut off at the curb or property line.

Key Characteristics of Curb Stops

• Installed on the service line, not the main

• Operated using a curb key from grade

• Typically installed in a curb box

• Common sizes: ¾″ to 2″

• Accessible from the surface

Typical Installation Location

• Near the property line

• In the public right-of-way

• Inside a curb box with extension rods as needed

Primary Purpose

Curb stops allow:

• Emergency shutoff without entering the building

• Seasonal shutoffs

• Maintenance without disturbing the water main

• Utility enforcement (vacancy, non-payment, repairs)

In many municipalities, the curb stop marks the transition of responsibility between the utility and the property owner.

Side-by-Side Comparison

Feature	Corporation Stop	Curb Stop
Installed In	Water main	Service line
Primary Function	Connect service to main	Shut off water to property
Accessibility	Buried	Surface access via curb box
Operated By	Municipality	Utility / authorized personnel
Inspection Focus	Proper tap & material	Proper depth & box alignment
Replacement Difficulty	High	Moderate

At A&A Equipment & Supply, we stock municipal-approved curb stops, corporation stops, curb boxes, rods, and accessories designed specifically for Illinois water projects.

Our team works directly with contractors to:

• Match local specifications

• Reduce inspection failures

• Minimize jobsite delays

• Ensure long-term reliability

Final Takeaway

Corporation stops and curb stops serve different but equally critical roles in water service installations. Understanding when—and where—to use each one helps contractors:

• Pass inspections the first time

• Avoid costly rework

• Deliver reliable water service to customers

• Protect long-term system integrity

Need the Right Valves for Your Next Water Project?

Visit https://aa.equipment or contact A&A Equipment & Supply to get contractor-grade curb stops, corporation stops, and complete water service materials—backed by local expertise and fast turnaround.