When the service line fails
A broken service line can flood a yard or cellar, or it can fail quietly under the lawn. Wet ground with no rain, a sudden drop in water pressure and a water meter that spins with everything off all point to the line. Close the main shutoff inside the house and call the 24/7 line.
If water is coming up outside, note where and tell the dispatcher. The plumber can often shut it off at the curb stop or arrange for the utility to do it. Do not dig into a wet area yourself, because other utilities may run nearby.
- Water bubbling up in the yard with no rain.
- A sudden loss of water pressure at every tap.
- A meter that runs when all fixtures are off.
- A wet cellar wall where the line enters the house.
- No water at all and a main shutoff that is already on.
What a service line is
The water service line runs from the main in the street to the meter or the main shutoff in your house. In many towns the utility owns the portion up to the meter or curb stop, and the homeowner owns the rest. Ownership rules differ, so ask the water department which section is yours before you hire anyone.
In Derry, the water department serves about 15,000 residents, institutions and businesses and can be reached at 603-432-6147. Homes on private wells have no service line from the street, but they have a line from the well to the house, and many of the same failure patterns apply.
Wet yard or sudden low pressure?
Close the main shutoff and call the 24/7 line.
Lead and galvanized service lines in Derry
The Derry Water Department published a 2025 lead service line inventory covering 4,466 lines. It lists 0 as lead, 2,302 as non-lead, 20 as galvanized requiring replacement and 2,144 as unknown. Owners of lines classified as galvanized requiring replacement or unknown can request a free lead test from the town.
If you do not know what your service line is made of, you can identify it where it enters your cellar. A magnet and a scratch test show whether it is steel or soft metal. Ask the plumber to check, and contact the water department about the free test. Source: derrynh.gov water department, lead service line inventory 2025.
Repair and replacement options
The right fix depends on the break, the pipe and the yard.
| Option | Best for | Trade-off |
|---|---|---|
| Spot repair | A single break in sound pipe | Other weak sections may remain |
| Open-trench replacement | Old galvanized or failed pipe | Disturbs the lawn or driveway |
| Trenchless replacement | Long runs beneath landscaping or pavement | Needs entry and exit pits |
| Meter-to-house section only | Failure inside the property line | Utility part must be arranged separately |
Digging, permits and utilities
Before anyone digs, call 811 so utility lines are marked. A service line replacement may need a permit or inspection, and the Derry code enforcement office at 603-432-6148 can confirm what applies. The water department may require its own approval for work at the main connection.
The plumber coordinates these steps and gives you a clear price before digging begins. Where the lawn or driveway will be disturbed, the plumber explains how it will be restored.
Low pressure is not always the service line
Low pressure can come from a failing pressure regulator, a partly closed valve, a clogged fixture or a leak in the house, so the plumber tests before digging. The plumber checks pressure at the hose bib, tests the regulator and uses the meter to look for flow. Our leak detection page explains the meter test.
Water Service Line Repair questions in Derry
Yes. The line is open 24/7. Close the main shutoff inside the house and call (603) 815-9179. The plumber works out whether the shutoff at the curb stop is needed.
Ownership is split in many towns. The utility often owns the part up to the meter or curb stop, and the homeowner owns the rest. Ask the Derry Water Department at 603-432-6147 where the boundary lies for your property.
Check the town's lead service line inventory and ask for a free test if your line is unknown or galvanized. A plumber can also inspect the pipe where it enters your cellar.
Open-trench replacement does disturb the lawn. Trenchless methods reduce that. The plumber explains the options and shows you the planned path.
Policies differ, and many exclude underground lines unless an endorsement is added. Ask your insurer before work begins.
References: Derry Water Department lead service line inventory 2025 (derrynh.gov). NH 811 before excavation. Derry code enforcement, 603-432-6148.
Service line leaking in Derry
Call any hour. The plumber finds the break and quotes a clear price before digging.