Slab Leak Repair in Portsmouth, NH

Slab Leak Repair After Confirmation

Slab leak repair is the work of stopping a confirmed leak in a pipe under or within a concrete floor. It is a separate step from finding the leak.

There is no single standard method. The right approach depends on the pipe, its route, the leak location and the rooms above.

Repair usually follows this order:

• Review the detection findings and confirm the leaking line.
• Choose between direct access, rerouting or replacing a section.
• Protect the rooms and finishes around the work.
• Complete and pressure-test the plumbing repair.
• Close or restore the floor, often as separate work.

What Must Be Confirmed Before Repair Starts

Repair should not start on suspicion alone. A few facts need to be settled first.

Before approving work, confirm:

• Which line is leaking: hot supply, cold supply or a drain.
• How the leak was located and how precise that location is.
• That other moisture sources, such as groundwater, were considered.
• Whether the leak is on your private plumbing, not a utility line.
• What pipe material is involved.

If any of these are uncertain, return to slab leak detection first. A wrong diagnosis is the most expensive mistake in slab work.

Supply-Line Versus Drain-Line Work

Supply-line and drain-line repairs under a slab are different jobs. They use different pipe, testing and often different access.

• Supply lines are pressurized and leak constantly. Rerouting is often possible because supply pipe is smaller and does not depend on slope.
• Drain lines rely on gravity and slope. They usually cannot be rerouted through walls or ceilings as easily.
• Testing differs. Supply repairs are pressure-tested; drain repairs are typically checked by flow or inspection.

This page focuses on supply-line repair. For drain concerns, describe odors or slow drains when you call.

Immediate Steps if Water Is Escaping

If water is surfacing through the floor or the meter is spinning fast, limit the loss first.

Do not chip or drill the floor to look for the pipe. That can create damage without fixing anything.

Accessing a Localized Section of Pipe

Direct access means opening the floor over the leak, repairing the pipe and closing the opening. It works best when the leak location is precise.

What direct access usually involves:

• Removing floor covering over the marked area.
• Cutting and removing a section of concrete.
• Excavating soil to expose the pipe.
• Repairing or replacing the damaged length.
• Testing, backfilling and patching the concrete.

The opening may need to be larger than expected to reach sound pipe on both sides. Ask how the size will be decided.

When Rerouting May Be Considered

Rerouting abandons the leaking under-slab section and runs new pipe another way. That route is usually through walls, ceilings or an attic.

Rerouting is often discussed when:

• The leak sits under cabinets, tile or hard-to-replace flooring.
• The pipe has leaked before in other spots.
• Several under-slab sections appear to be in poor condition.
• Direct access would disrupt a busy kitchen or bathroom.

A reroute trades floor damage for wall or ceiling openings. Those openings are often smaller, but they still need patching.

When a Pipe Section May Be Replaced

Section replacement fixes more than the leak point. It replaces a longer run of pipe under the slab, often using the same route.

It may be considered when the pipe shows wear beyond the leak, and rerouting is impractical.

This usually means larger or multiple floor openings. Ask how much pipe is being replaced and why that length was chosen.

Comparison: Direct Access Versus Reroute

None of these is right for every building. The decision should rest on findings at your property.

What Foundation Access May Involve

Opening a slab is structural work on part of the building. It needs care around reinforcement, vapor barriers and insulation.

Questions to raise about foundation access:

• Is there rebar, wire mesh or post-tension cable in the slab?
• Is there a vapor barrier or insulation under the concrete?
• Are there radiant heating tubes or electrical conduit nearby?
• How will dust be controlled during cutting?
• How will the patch be matched and cured?

Post-tensioned slabs need special caution before cutting. Ask the provider how they confirm slab construction first.

Risks of Unnecessary Concrete Opening

Opening concrete in the wrong place costs money and leaves damage behind. It is the main reason careful detection matters.

Risks include:

• Repairing nothing because the leak is elsewhere.
• Damaging other pipes, conduit or heating loops.
• Disturbing vapor barriers and inviting future moisture.
• Larger flooring replacement than the repair required.
• Extended loss of use of a kitchen or bathroom.

If confidence in the location is low, ask whether a reroute avoids the risk entirely.

Pipe Material and Condition Considerations

The pipe’s material and condition shape the repair choice. A single pinhole in sound pipe is different from widespread wear.

Points to discuss:

• What material the under-slab line is made of.
• Whether the exposed pipe shows corrosion, thinning or abrasion.
• How new pipe will join old pipe safely.
• Whether the same pipe has leaked before.

Ask the provider to show you the removed section or photos. That evidence helps you decide whether a larger replacement is justified.

How Repair Work Can Affect Rooms

Slab repair affects how you use the building during the work. Planning ahead reduces disruption.

Expect possible impacts such as:

• Water shut off for part or all of the work.
• Furniture and appliances moved away from the area.
• Dust and noise during concrete cutting.
• A kitchen or bathroom unusable for a period.
• Open floor or wall areas while materials cure.

Ask for a realistic schedule, including curing time for patched concrete.

Repair Boundaries Versus Finish Restoration

The plumbing repair and the floor finish are often separate jobs. Clarify who does what before work starts.

Tile, hardwood and cabinetry often need a flooring or carpentry contractor. No plumbing quote should be assumed to include perfect finish restoration.

Permits and Other Scope Questions

Some plumbing repairs require a permit and inspection. Whether yours does depends on the work and the municipality.

In Portsmouth, plumbing permit applications go through the Inspection Department. Questions can go to (603) 610-7243. See Permit Applications, reviewed October 2026.

Ask the provider:

• Does this repair need a permit, and who files it?
• Will an inspection be needed before the floor is closed?
• Are there condominium or landlord approvals to obtain first?

No one can promise a permit outcome or inspection timing.

How Repair Is Tested Before Closure

The repaired line should be tested before concrete, flooring or walls are closed. Testing after closure means reopening if something fails.

Typical checks include:

• Pressure-testing the repaired or new line.
• Inspecting joints for drips while exposed.
• Confirming the old line is properly capped if rerouted.
• Checking the meter stays still with fixtures off.

Ask to see the test or a photo of it. It is the clearest evidence that the repair holds.

Call (844) 442-1700 to ask how a provider would verify a slab repair at your property.

(844) 442-1700

What Can Change a Slab Repair Estimate

Estimates can shift once concrete is open or a route is traced. Knowing the common reasons helps you plan.

• The leak sits slightly away from the marked location.
• The pipe is deeper than expected under the slab.
• Additional damaged pipe is found beside the leak.
• Slab construction requires extra care to cut.
• A reroute path meets framing, ducts or wiring.
• Moisture under the slab needs time to dry.

Pricing comes from the provider. For how detection, repair and restoration costs differ, read about leak detection cost in New Hampshire.

Questions to Ask About Site Protection

Concrete work creates dust and debris. Ask how the rest of the building will be protected.

• How will the work area be sealed from other rooms?
• How will dust be controlled during cutting?
• Will floors along the access path be covered?
• Where will removed concrete and soil be stored?
• Who cleans up when the work is complete?

Good answers here reduce cleanup costs that are easy to overlook.

What if the Leak Location Changes?

Sometimes the leak is not exactly where testing suggested. The plan for that situation should be agreed before work starts.

Agree in advance on:

• How the provider will confirm the location once the floor is open.
• Whether they will pause before enlarging the opening.
• Whether switching to a reroute is an option mid-job.
• How additional work will be priced and approved.

A pause for your decision is reasonable. An unapproved larger excavation is not.

Moisture Management After the Plumbing Work

Fixing the pipe does not dry the area under and around the slab. Trapped moisture can affect flooring and air quality.

After repair, consider:

• Measuring moisture in nearby flooring and walls.
• Allowing time for drying before installing new flooring.
• Running dehumidification if humidity stays high.
• Calling a water-damage restoration company for larger wet areas.

Moisture drying is a separate service from plumbing repair. Ask your insurer what documentation it needs.

Alternatives When the Suspected Leak Was Not a Pipe

Sometimes investigation shows no pipe leak at all. That is useful information, not a failure.

The moisture may come from:

• Groundwater or high soil moisture under the slab.
• Condensation on cold concrete in humid weather.
• Rain entering at thresholds or foundation cracks.
• An appliance, shower or tub leak.

These need different help, such as drainage, waterproofing or fixture repair. For general fixture and pipe repairs, see water leak repair.

Related Slab Diagnosis and Line Services

Slab repair often connects to other services. These pages cover the neighboring questions:

• Slab leak detection for confirming and locating the leak.
• Concealed pipe leak repair for in-wall work, including some reroutes.
• Water leak repair for fixture and accessible pipe leaks.
• Leak detection cost in New Hampshire for comparing quote scopes.

Call (844) 442-1700 when you are ready to discuss repair options with the provider.

(844) 442-1700