Plumbing Permit in New Castle County, Delaware
Permit required
Yes, a permit is required
Before installing, replacing or altering any plumbing system or gas piping.
Issued byNew Castle County Department of Land Use
By Mario Bailey, verified against official sources
Quick answer
A County plumbing/gas permit is required to install, alter, repair, convert or replace any plumbing system or gas piping in unincorporated New Castle County. Exemptions are narrow: stopping leaks, clearing stoppages, and removing and reinstalling an existing fixture in place without replacing valves, pipes or fixtures; replacing defective concealed piping is new work that needs a permit. Owner-occupiers may pull a residential plumbing permit for their own home, but not for gas piping.
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When a permit is usually needed
Before installing, replacing or altering any plumbing system or gas piping.
What a plumbing permit costs in New Castle County
How to apply in New Castle County
In New Castle County, you apply for a residential plumbing permit at your local building department by filing an application that describes the scope of work and site, along with construction documents, before any regulated plumbing installation, alteration, or repair begins. Minor repairs that do not touch piping or fixtures are generally exempt, and once issued the permit only stays valid if work is started within its time limit.
What most plumbing permit applications include:
- For New Castle County, a permit is required before any owner or authorized agent constructs, alters, repairs, removes, converts, or replaces a plumbing system regulated by the code (IRC R105.1).
- For New Castle County, the application must identify and describe the work, describe the site, state the intended use and occupancy, and be signed by the applicant or an authorized agent (IRC R105.3).
- Two or more sets of construction documents must accompany the application, drawn with enough clarity to show the location, nature, and extent of the proposed plumbing work and how it will conform to code (IRC R106.1, R106.1.1).
- Minor plumbing repairs, such as clearing a stoppage or removing and resetting a water closet without rearranging pipes or fixtures, are exempt from permit (IRC R105.2).
- Once issued, a permit is only valid for a limited window, commonly 180 days, and becomes invalid if the work is not started or is abandoned within that time, though extensions can be requested (IRC R105.3.2, R105.5).
General submittal guidance from 2021 International Residential Code (IRC), Chapter 1 Scope and Administration, Sections R105 Permits and R106 Construction Documents. Source. New Castle County Department of Land Use sets the exact checklist for New Castle County.
Where to apply in New Castle County:
New Castle County Department of Land Use
- New Castle County Government Center, 87 Reads Way, New Castle, DE 19720
- Phone: 302-395-5400
- Email: permits@newcastlede.gov
Plumbing Permit in New Castle County compared with nearby Delaware localities
| Locality | Permit needed? | Threshold | What each Delaware schedule says | Verified |
|---|---|---|---|---|
| New Castle County | Permit required | Any size | ...6 Schedule of Permit and Review Fees, as amended through January 1, 2026): $5.25... | |
| Sussex County | Permit required | Any size | Division of Public Health: $100 per plumbing permit (covers 3 inspections) |
Inspections and closing out your permit
In New Castle County, plumbing inspections are timed to whatever is about to hide the pipe: underground and under-slab piping is checked before concrete covers it, rough-in piping is pressure or water tested before walls close up, and a final inspection checks every fixture and backflow protection once the work is complete.
- In New Castle County: piping and equipment placed under a slab or floor must be in place and inspected before any concrete is poured or floor sheathing is installed over it (IRC R109.1.1.1).
- In New Castle County: rough plumbing, along with the mechanical, gas, and electrical rough-in, must be inspected prior to covering or concealment and before fixtures or appliances are set (IRC R109.1.2).
- In New Castle County: rough drain, waste, and vent (DWV) piping is tested with water, air, or (for plastic piping) a vacuum, and must show no evidence of leakage before it is closed in (IRC P2503.5.1).
- In New Castle County: the water-distribution piping is tested and must hold tight under the system's working pressure, or under a 50 psi air test for non-plastic piping, before it is concealed (IRC P2503.7).
- In New Castle County: the framing inspection cannot proceed until the plumbing rough inspection, along with the mechanical and electrical rough inspections, has been approved (IRC R109.1.4).
- In New Castle County: at the final drainage test, each fixture is filled and then drained, and its traps and fixture connections must prove watertight by visual inspection (IRC P2503.5.2).
- In New Castle County: final inspection is made after all work required by the permit is complete, and includes confirming backflow protection, such as vacuum breakers on hose bibbs, is installed (IRC R109.1.6, P2902.4.3).
Schedule each inspection in advance and pass the final before you use the work or close the permit. Request inspections through the New Castle County permit portal or by phone at 302-395-5400.
Inspection sequence from 2021 International Residential Code (IRC), Section R109 Inspections and Section P2503 Inspection and Tests. Source. An open permit left un-inspected can surface later in a title search or home sale.
Your Plumbing Permit checklist for New Castle County
- Confirm the requirement. Yes, a permit is required. Usually needed: Before installing, replacing or altering any plumbing system or gas piping.
- Budget the fee. Mechanical or Plumbing Permit (Chapter 6 Schedule of Permit and Review Fees, as amended through January 1, 2026): $5.25 for the first $1,000 valuation or any part thereof, $5.25 for each additional $1,000 or part thereof, minimum fee $65.00. Official fee schedule.
- Apply. In New Castle County, you apply for a residential plumbing permit at your local building department by filing an application that describes the scope of work and site, along with construction documents, before any regulated plumbing installation, alteration, or repair begins. Minor repairs that do not touch piping or fixtures are generally exempt, and once issued the permit only stays valid if work is started within its time limit. Start at the New Castle County permit portal.
- Keep the office details handy. New Castle County Department of Land Use. Phone: 302-395-5400. Address: New Castle County Government Center, 87 Reads Way, New Castle, DE 19720.
- Plan for inspections. In New Castle County, plumbing inspections are timed to whatever is about to hide the pipe: underground and under-slab piping is checked before concrete covers it, rough-in piping is pressure or water tested before walls close up, and a final inspection checks every fixture and backflow protection once the work is complete.
Compiled from the official sources on this page. Last checked .
Frequently asked questions
- Do you need a plumbing permit in New Castle County?
- A County plumbing/gas permit is required to install, alter, repair, convert or replace any plumbing system or gas piping in unincorporated New Castle County. Exemptions are narrow: stopping leaks, clearing stoppages, and removing and reinstalling an existing fixture in place without replacing valves, pipes or fixtures; replacing defective concealed piping is new work that needs a permit. Owner-occupiers may pull a residential plumbing permit for their own home, but not for gas piping. Always confirm with the New Castle County Department of Land Use before starting.
- How much does a plumbing permit cost in New Castle County?
- Mechanical or Plumbing Permit (Chapter 6 Schedule of Permit and Review Fees, as amended through January 1, 2026): $5.25 for the first $1,000 valuation or any part thereof, $5.25 for each additional $1,000 or part thereof, minimum fee $65.00. See the official fee schedule for current amounts.
- Where do you apply for a plumbing permit in New Castle County?
- You can apply through the New Castle County permit portal or contact the New Castle County Department of Land Use directly. The links are listed on this page.
- Can a homeowner pull a plumbing permit themselves in New Castle County?
- Under Delaware law (9 Del. C. 6302(b); 9 Del. C. 4402(b); 24 Del. C. 1417; 24 Del. C. 1807(c)(2); 24 Del. C. 1820(c)(2); 16 Del. C. 7906(c)): Yes. Delaware homeowners may pull permits and do their own work, with trade-specific conditions. Sussex County's statute expressly lets any owner who wants to do their own work on their own building get a permit, and Kent County issues permits in the owner's name. For electrical work, a homeowner wiring their own home that is not for sale or rent must get a homeowner's permit from the Board of Electrical Examiners and pass a final inspection; swimming pools and hot tubs are excluded. Homeowners may do their own plumbing and HVACR work (but not gas piping) in their own home that is not for sale, rent or lease, and for plumbing must file a permit application with the inspection authority. Confirm how New Castle County applies this before you apply.
From the Library
What else needs a permit in New Castle County
Every other permit type we have verified for this jurisdiction, with the rule that applies here.
| Project | Permit needed? | Threshold | Typical fee |
|---|---|---|---|
| Bathroom Remodel Permit | It depends | Finish work (tiling, cabinets, counter tops) and in-place fixture reinstallation are exempt; new or moved plumbing, walls or circuits are not | 11/04/2025): "Building Permit Fee: $12 per $1,000 of Valuation ($142 Minimum)"... |
| Deck Permit | It depends | Floor area of a free-standing deck no more than 30 inches above grade and not adjacent to or attached to the dwelling | 11/04/2025): "Building Permit Fee: $12 per $1,000 of Valuation ($142 Minimum)"... |
| Electrical Permit | Permit required | Any size | See schedule |
| EV Charger Permit | Permit required | Any size | See schedule |
| Fence Permit | It depends | Only fences that serve as swimming pool barriers need a permit | Not published |
| HVAC Permit | Permit required | Any size | ...6 Schedule of Permit and Review Fees, as amended through January 1, 2026): $5.25... |
| Patio Permit | It depends | Height of a non-structural slab, patio or decorative hardscaping at any point | Not published |
| Pool Permit | It depends | Pool, spa or hot tub wall height; any pool designed to connect to a circulation system needs a permit regardless of height | 11/04/2025): "Building Permit Fee: $12 per $1,000 of Valuation ($142 Minimum)"... |
| Roof Replacement Permit | It depends | Share of the roof sheathing repaired or replaced during a re-roof | 11/04/2025): "Building Permit Fee: $12 per $1,000 of Valuation ($142 Minimum)"... |
| Shed Permit | It depends | Floor area of a one-story detached accessory structure with an eave height of 10 feet or less and overall height of 20 feet or less; garages never qualify | 11/04/2025): "Building Permit Fee: $12 per $1,000 of Valuation ($142 Minimum)"... |
| Solar Permit | It depends | Rooftop panels on a one- or two-family dwelling are exempt from the County building permit; electrical work still goes through the State | Not published |
| Water Heater Permit | Permit required | Any size | ...6 Schedule of Permit and Review Fees, as amended through January 1, 2026): $5.25... |
Plumbing Permit in other Delaware localities
Everything above, sourced
Code references
National and state model-code sections the general guidance on this page is drawn from. They are not New Castle County documents; the office above sets the local rules.
How this plumbing permit page for New Castle County was verified. 2 official sources: newcastlede.gov, newcastlede.gov; fee schedule: official document. Last checked by Mario Bailey, not confirmed with New Castle County Department of Land Use. Rules change; confirm before you build. How we verify.
Last checked: Report an error on this page
Compare Plumbing Permit requirements across Delaware localities