What is a main water line, and when is it replaced?

The main water line, also called the service line, is the primary pipeline that delivers water from the municipal supply to your property. Most of it is buried between the meter box near the street and the point where it enters your house. That's why you rarely see it until something goes wrong.

Ownership splits at the meter. The City of Phoenix says issues on the city's side, from the street to the water meter, are the city's responsibility, and issues after the meter are the homeowner's. So a leak in the buried pipe between your meter and your house is on you, including the water you pay for while it runs. For a leak happening right now, see who to call about a water leak in Phoenix. If you're not sure whether a problem is on your side, our guide to a high water bill with no visible leak and how to do a water meter leak test show how to check.

One more thing that trips people up. This is a different pipe from your sewer line. The water line brings clean water in under pressure. The sewer line carries waste out by gravity. Who is responsible for your sewer line in Phoenix covers that side.

These are the usual signs of a failing main line:

• Reduced water pressure at fixtures
• Discolored or unusual-tasting water
• Wet spots or patches of grass greener than the rest of the yard, which Cal Water says could indicate a leak in the pipe
• Unexplained spikes in your water bill
• Dampness near where the line enters the house

Any one of these can have another cause. Low pressure at one faucet is usually that faucet. Low pressure at every fixture points toward the main line, along with a failing pressure regulator, so low water pressure in the whole house is worth reading first. A wet patch in the yard could be an irrigation line. A bill spike could be a running toilet.

What points at the main line is a combination. If your meter dial keeps moving when everything is off, and the yard is wet or the pressure is down, the buried pipe is the prime suspect. A leak detection visit can confirm the spot before anyone digs. For the yard-side checks, see how to find a water leak in your yard.

Phoenix has a program worth knowing about, because it can save you the whole job. To meet the federal Lead and Copper Rule, the city inventoried over 480,000 service lines and submitted the inventory to the Arizona Department of Environmental Quality by October 16, 2024. The inventory focuses on lines installed before 1988, when lead pipe was prohibited.

The city reports that no existing lead service lines have been found in Phoenix, based on field investigations of over 250,000 lines since 2021. But some lines are classified as galvanized requiring replacement, and those, along with "unknown" lines, triggered mailed notices to homeowners. The city explains why: "Galvanized service lines can also pose a health risk because the zinc coating corrodes over time, potentially leaching lead particles." It stopped using the material in 1983.

Here's the part that matters to your wallet. On the city's lead service line site, Phoenix says: "The City covers the entire cost of this service line replacement work" for identified galvanized lines, and the work replaces the line from the city meter box to the hose bib or connection at the house. The city said it would begin replacing lines through a planned program starting in 2025, and it plans to use federal grants through the Bipartisan Infrastructure Law.

To check your own line, go to pipes.phoenix.gov and look up your address, or check the notice the city mailed you. If your line is flagged, don't pay a contractor to replace it before you've talked to the city, since the city may do it for free. Our page on galvanized pipe problems covers what the same pipe does inside a house.

You don't have to guess. Work through this list in order, and stop when you find the answer.

1. 1Read your meter with everything off. A moving flow indicator means water is escaping. How to do a water meter leak test has the steps.
2. 2Walk the line. The buried line runs from the meter box toward the house. Look for soggy ground, unusually green grass, sunken soil or a hiss along that path.
3. 3Look up your address at pipes.phoenix.gov. If the city shows your service line as galvanized requiring replacement, or unknown, call the city before you hire anyone. It may replace the line at its own cost.
4. 4Check your pressure. Pressure that drops in every fixture, or discolored water when you turn on a tap, are the two signs that most often point at the line itself.
5. 5Get it located. A plumber can pinpoint the failure with listening and locating equipment, so you're not digging blind.

If you live outside Phoenix, don't assume the same rules apply. Other Valley cities set their own service line policies, and a few have their own inventories, so start with your city's water department. Phoenix's program is the one described here. Either way, the same meter test and yard checks apply, and the same principle holds: find the leak first, then decide between a repair and a replacement. A short section of failed pipe can sometimes be repaired, while a line that keeps failing usually means replacing the run.

There are two basic approaches. Traditional replacement digs a trench along the old line and lays new pipe. Trenchless methods work from the two ends and avoid digging up the whole yard, which helps when the line runs under a driveway, patio or landscaping. Older lines, especially galvanized steel, are the ones most likely to be replaced.

Which one fits depends on the line's depth, what's above it, and the pipe's condition. Before you agree to anything, ask: For the cover depths Phoenix sets for new mains and meter connections, see how deep a residential water main is buried in Phoenix.

1. 1Where exactly is the leak or failure, and how was it found?
2. 2Is the city flagging this line as galvanized, and would the city replace it?
3. 3Trench or trenchless, and what gets dug up and restored?
4. 4What pipe material goes in, and who pulls the permit and schedules the inspection?
5. 5What's the price in writing before work starts?

HQ gives free estimates and upfront pricing, and we offer 24/7 emergency service if a line has failed and water is running. If a main line is spraying, shut off the water at your house valve and call. Don't try to turn off the water at the city's meter yourself. Phoenix says to use the valve near where the water enters your home, and if that valve doesn't work or is broken, to call the city at 602-261-8000 to have the water turned off at the meter.