Service Line — Water Supply Pipe from Main to Home

A service line is a water supply pipe that runs from the municipal water main at the street to the water meter and into a building, delivering potable water to the structure.

What It Is

The service line is the buried connection between the public water distribution system and a private property. It begins at a corporation stop tapped into the main, runs underground through the easement and property, passes through or near the foundation wall, and terminates at the water meter and main shutoff valve inside or at the building. This pipe carries the entire water supply for the building, so its size, condition, and material directly affect flow rate and water quality throughout the structure.

Ownership of the service line is typically split. The utility owns the portion from the main to the curb stop or meter box. The property owner owns the remainder from the curb stop to the building. This distinction matters for repairs — the utility handles their section, and the property owner is responsible and financially liable for the private portion.

Service lines in older neighborhoods are frequently made of lead, galvanized steel, or polybutylene, all of which carry replacement recommendations or requirements due to health or reliability concerns. Lead service lines in particular are a major public health issue, and federal and state programs are increasingly funding or mandating their replacement.

Types

Copper service lines are the standard for modern installations and offer corrosion resistance and long service life. Galvanized steel lines were common in homes built before the 1960s and corrode from the inside, reducing flow and releasing rust. Lead service lines predate 1940 in most areas and are the highest priority for replacement. Polybutylene was installed from the 1970s through the 1990s and is prone to cracking and failure. Modern installations also use HDPE and PVC C900 pipe. The minimum size for a residential service line is typically 3/4 inch, with 1 inch being common for most homes.

Where It Is Used

Every building connected to a public water system has a service line. It runs underground from the street to the building, typically at a depth of 12 to 48 inches depending on local frost depth requirements.

How to Identify One

The service line is not directly visible; it is buried. The pipe enters the building through the foundation wall or floor and connects to the water meter and main shutoff valve. The material can sometimes be identified at the meter connection — lead pipes are soft and can be scratched to reveal shiny silver metal, copper is orange-brown, galvanized is grayish steel. A water utility or licensed plumber can trace and identify the service line material using the utility's records or inspection.

Replacement

Service line replacement is required when the pipe is lead, galvanized steel with heavy corrosion, polybutylene, or any material that has failed or is failing. Replacement involves excavating the trench along the service line run, disconnecting from the corporation stop and the building entry, installing new pipe, and backfilling. Permits are required in virtually all jurisdictions for service line replacement, and utility coordination is needed to shut off and reconnect the corporation stop.