New Castle County Plumbing Permits: Water Line, Gas Line, Water Heater

The short answer

In unincorporated New Castle County, the Department of Land Use issues plumbing permits, and the county code requires one before you install, alter, replace, or remove a plumbing or gas system, including a water heater. Stopping a leak, clearing a clog, or swapping a sump pump is exempt. Wilmington, Newark, Middletown, New Castle, Smyrna, and several smaller towns run their own permit offices.

Three questions come up in the searches that reach this page. Outside town limits:

• Replacing a water service line: permit required. The county’s plumbing permit application lists water service to the building as permitted work, and the plumbing code Delaware adopts counts the water service as part of the plumbing system.
• Extending a gas line: permit required, and the county’s owner-occupier exception excludes gas piping, so a licensed contractor applies.
• Replacing a water heater: permit required, which brings an inspection. The state’s like-for-like exemption does not apply in the county.

The rules below are quoted from the county code, a county permit form, the state plumbing code, or a municipality’s own site, and linked. Where an answer is our reading of those documents rather than a direct quote, the text says so. If you are planning a repipe, water heater swap, or bathroom addition anywhere in the New Castle County towns Spangler serves, start by asking whose permit office covers the address.

Which plumbing jobs typically require a permit

New Castle County’s building code, Chapter 6, says anyone who intends “to erect, install, enlarge, alter, repair, remove, convert or replace any gas, mechanical, or plumbing system” it regulates “shall first make application to the Code Official and obtain the required permit” (NCC Code, Chapter 6, Sec. 06.03.012).

The same section lists the plumbing work that needs no permit, quoted from Sec. 06.03.012(C)(5):

• “The stopping of leaks in drains, water, soil, waste or vent pipe,” with a catch: if a concealed trap or pipe is defective and must be removed and replaced with new material, “such work shall be considered as new work and a permit shall be obtained and inspection made.”
• “The clearing of stoppages or the repairing of leaks in pipes, valves or fixtures, and the removal and reinstallation of an existing fixture in its present location,” provided the repair does not involve “the replacement or rearrangement of valves, pipes, or fixtures.” Then: “This exemption shall not apply to the installation or replacement of a water heater.”
• “Sump pumps, or the replacement thereof.”

(NCC Code, Sec. 06.03.012)

The water heater line trips people up. Generic Delaware advice often says a like-for-like replacement needs no permit, and that is the state rule where the Division of Public Health permits directly: no Division permit is required “for the replacement of an existing fixture, piece of equipment or related piping, including but not limited to hot water heaters” (16 DE Admin. Code 4455). The county’s own list carves water heaters out.

A whole-house repipe sits squarely inside the permit requirement, as do moving a fixture, adding a bathroom, and running gas to a range. An emergency does not waive it: for repairs that “must be performed in an emergency situation, the permit application shall be submitted within the next business day” (Sec. 06.03.012(D)).

Water service lines and gas lines

The buried pipe from the street to your house is covered too. The 2021 plumbing code Delaware adopts defines a plumbing system as including “the water service, building sewer and building storm sewer serving such structure or premises,” and defines the water service pipe as the pipe “from the water main or other source of potable water supply, or from the meter when the meter is at the public right of way, to the water distribution system of the building served” (2021 Delaware Plumbing Code, Sec. 202). The county’s own plumbing permit application lists water service to the building among the work it covers, including replacement (NCC Plumbing/Gas Permit Application). Read together with the code, replacing that line is replacing part of a plumbing system, and the county’s leak exemption stops once defective pipe “must be removed and replaced with new material.” Where your pipe ends and the water utility’s begins depends on the utility; who owns the water and sewer line to your house walks through Artesian, Veolia, Middletown, and county rules. Call the utility before anyone digs near the curb stop or meter.

Gas is named in the permit requirement itself, which covers anyone intending to “enlarge, alter, repair, remove, convert or replace any gas, mechanical, or plumbing system” (Sec. 06.03.012). Extending a line to a new range, dryer, generator, or fireplace enlarges the system. The county posts a separate Plumbing Gas Permit Application and Gas Pipe Requirements and Guidelines on its Utility Permits page, and the homeowner exception described below does not cover gas piping.

Who is responsible for pulling it

The county code puts the application duty on “any permit contractor endorsement holder, or owner in accordance with the exceptions” in that section (Sec. 06.03.012(A)). In practice, the licensed plumber applies. A plumbing contractor needs a county permit-endorsed contractor license, and the county requires a copy of the license holder’s current State of Delaware trade license from the Division of Professional Regulation to issue one (NCC 2026 Utility Contractor Requirements). You can confirm a plumber’s state license on the Division of Professional Regulation license lookup.

Applications go through the county’s eServices system (Get a Permit). The code also has an “Owner-occupier residential plumbing permit” exception for an owner working on their own home that is not for sale or partly rented, excluding gas piping (Sec. 06.03.012(A), Exception 2). If you plan to do your own work, read that exception in full and call Land Use first.

Whoever applies, the permit holder carries the inspection duty: it “shall be the duty of the holder of the permit or their duly authorized agent to notify the Code Official when work is ready for inspection” (NCC Code, Chapter 6). Before any plumber starts, ask two plain questions: who is applying for the permit, and will you get the permit number.

What an inspection actually checks

An inspection is not a formality at the end. Work “shall not be done beyond the point indicated in each successive inspection without first obtaining the approval of the Code Official,” and any portion that fails “shall not be covered or concealed until re-inspected and authorized” (NCC Code, Chapter 6). Translated: the inspector needs to see the pipe before the drywall goes back on.

For a permitted residential project, the sequence includes a close-in inspection made “in conjunction with any required approvals of the rough plumbing, mechanical and electrical inspections,” and a final inspection “after the permitted work is complete and prior to occupancy” (NCC Code, Chapter 6). Inspections are scheduled at inspections.newcastlede.gov around the clock, with an email to the permit holder at 7 a.m. on inspection day (Building Inspections). One boundary: “electrical permitting and inspections are handled through the State of Delaware” (Utility Permits).

The standard is the Statewide Plumbing Code. The county code directs Land Use to enforce “the most recent version of the International Plumbing Code published by the International Code Council as adopted and modified by the Delaware Division of Public Health” (Sec. 6.07.001). The Division’s current regulation adopts the 2021 International Plumbing Code with Delaware amendments (16 DE Admin. Code 4455; DPH Plumbing Program).

Municipalities inside the county with their own rules

The county is the permit office only for property outside an incorporated municipality. Inside city or town limits, the municipality issues the permit and its exemptions can differ. The test is municipal limits, not the postal address. Confirmed from each municipality’s own site:

• Wilmington. Permits, including a Plumbing Permit Application, go through the Department of Land Use & Planning at 800 N. French Street, which runs its own permit search portal (City of Wilmington, Permits & Applications).
• Newark. The Code Enforcement Division’s inspectors “review your plans, issue permits, and conduct all inspections,” a city contractor’s license is required for paid work, and the city cites the 2018 International Plumbing Code (City of Newark, Building Permits). Its permit guide lists “New Plumbing or Plumbing Alterations” as always requiring a permit (Guide to Building Permits).
• Middletown. The town issues permits from 19 W. Green Street, and plumbing and HVAC contractors need a Town of Middletown business license plus the applicable Delaware professional license before obtaining a permit (Permits, Licensing, Inspections; Business License & Building Inspections).
• City of New Castle. The Building Department at 220 Delaware Street accepts applications for “the various permits issued by the City” (City of New Castle, Building & Zoning).
• Smyrna. The town “requires permits for plumbing, heating, ventilation and air conditioning installation,” and inspections need 24-hour notice (Town of Smyrna, Permits & Applications; Inspections).
• Odessa. Building, plumbing, HVAC, and electrical permits are submitted to the Town Office at 315 Main Street, and the town contracts with 1st State Inspection Agency for “ALL building, plumbing, electrical & HVAC inspections” inside town limits (Town of Odessa, Building Permits).
• Townsend. The town’s Building Permit Application covers “all projects requiring a permit including HVAC & Plumbing,” and contractors based outside town file a Town of Townsend contractor’s license application (Town of Townsend, Forms and Permits).
• Clayton. The town took over plumbing permitting and inspections from the state Department of Health & Social Services effective September 15, 2025; applications go to Town Hall at 414 Main Street (Town of Clayton, Plumbing Permitting and Inspections).

Town arrangements change; Clayton’s did in 2025. Before work starts, call the permit office for the property’s address and ask who issues the plumbing permit and who inspects it.

Unpermitted work found during a home sale

Usually a home inspector or plumber notices a water heater, bathroom, or gas line newer than any permit on record. The county code treats work done without a permit as a violation, and its fee schedule adds a “working without a permit” charge on top of the normal permit fee (NCC Code, Chapter 6, Article 12 and Appendix). Whether a job needs an after-the-fact permit or corrective work is that permit office’s decision.

On disclosure, Delaware law requires that the seller or agent give the Seller’s Disclosure of Real Property Condition Report to prospective buyers “prior to the time the buyer makes an offer to purchase” (6 Del. C. § 2573); the Real Estate Commission publishes the forms (Division of Professional Regulation). What you must say on that form is a question for your agent or an attorney; a plumber can tell you whether the work is sound and what would have to change to pass inspection.

Questions homeowners ask

Do I need a permit to replace my water service line?

In unincorporated New Castle County, yes. That is our reading of the county’s documents; no single line says it word for word. The county’s plumbing permit application lists water service to the building, including replacement. The plumbing code Delaware adopts includes the water service in the plumbing system. The county requires a permit to replace any part of that system, and replacing pipe with new material is not covered by the leak-repair exemption (NCC Plumbing/Gas Permit Application; 2021 Delaware Plumbing Code, Sec. 202; Sec. 06.03.012). Inside a town, ask its permit office, and check with your water utility about work at the curb stop or meter.

Do I need a permit to extend a gas line?

Yes, outside town limits. The county’s permit requirement names gas systems, extending a line enlarges one, and the owner-occupier exception excludes gas piping, so a licensed contractor with a county permit endorsement applies (Sec. 06.03.012; Utility Permits).

Do I need a permit to replace a water heater in New Castle County?

Yes, outside municipal limits. The county’s repair exemption “shall not apply to the installation or replacement of a water heater” (Sec. 06.03.012(C)(5)). Inside a municipality, ask its permit office.

Does Delaware require an inspection after a water heater replacement?

It depends on who issues permits for your address. In unincorporated New Castle County the swap needs a permit, and the permit holder must notify the county when the work is ready for inspection (NCC Code, Chapter 6). Where the Division of Public Health issues permits, no Division permit is required for replacing an existing water heater (16 DE Admin. Code 4455). Towns set their own rules. If you are replacing a tank, our water heater service page covers what we install.

Does fixing a leak or clearing a clog need a permit?

Not in the county, as long as it stays a repair. Stopping leaks, clearing stoppages, and reinstalling an existing fixture in place are exempt. Once concealed pipe is replaced with new material, or valves, pipes, or fixtures are replaced or rearranged, the code calls it new work (Sec. 06.03.012(C)(5)).

Can I pull my own plumbing permit as a homeowner?

The county code has an owner-occupier residential plumbing permit exception for an owner working on their own home that is not for sale or rent, excluding gas piping (Sec. 06.03.012(A)). Confirm the conditions with the Department of Land Use before relying on it.

What plumbing code does New Castle County use?

The Statewide Plumbing Code, meaning the International Plumbing Code as adopted and amended by the Delaware Division of Public Health (Sec. 6.07.001). The state’s current regulation adopts the 2021 edition (16 DE Admin. Code 4455).

How can I check whether past plumbing work was permitted?

The county’s inspection site shows permit details and results by permit number, and its Permits & Inspections page links a permit-status lookup (Building Inspections; Permits & Inspections). For a town, ask its permit office.

Before the work starts

Find out which office covers your address, ask your plumber who is applying for the permit, and keep the permit number and inspection results with your house records. Those three steps settle most of the questions that come up at resale. If you are weighing a repipe, water heater replacement, or bathroom addition in the New Castle County communities Spangler serves, get in touch and we can talk through the scope before anyone applies for anything.