A Delaware plumbing license means one thing: the Master Plumber license. Delaware does not issue a separate state journeyman or apprentice plumbing license, so if you are not a master, you can only do plumbing work while supervised by a master plumber who employs you or works full time for the same company.
Who issues the license
Plumbing licenses in Delaware come from the Delaware Board of Plumbing, Heating, Ventilation, Air Conditioning and Refrigeration Examiners, which sits inside the Division of Professional Regulation (DPR). It is a combined board. The same nine-member board also licenses Master HVACR and Master HVACR Restricted contractors, so you will see plumbing and HVACR info mixed together on most of its pages.
Licensing is statewide under Title 24, Chapter 18 of the Delaware Code. Counties and towns do not issue their own plumber licenses, but the law lets them adopt and enforce plumbing and fuel gas codes and run their own permits and inspections.
Requirements change, so always confirm with the Delaware Board of Plumbing, Heating, Ventilation, Air Conditioning and Refrigeration Examiners before you apply. This page is a plain-English guide, not legal advice.
License types
- Master Plumber. The only individual plumbing license the state issues. It covers designing, installing, repairing, and altering water supply and drainage piping and fixtures, plus installing and connecting gas piping.
- Temporary license. This is a narrow case. If a plumbing company loses its only license holder, the law lets the board issue a 100-day temporary license to an owner or employee, who then has to take the next available exam.
- Working under a master. Apprentices, journeymen, and mechanics can legally work without their own state license only when supervised by a master plumber who is their employer or is a full-time employee of the same business.
Homeowners can do their own plumbing (not gas piping) in a home they live in and are not selling or renting, as long as they file for a permit. Heating, cooling, and refrigeration work is separate. That needs a Master HVACR or Master HVACR Restricted license, even if you already hold a plumbing license.
Experience requirements
Delaware counts years of supervised work, not a set number of classroom hours. There are two routes to the master exam:
- With a journeyman certificate. You finished a plumbing apprenticeship that meets or beats federal apprenticeship standards and got a journeyman certificate (from any state). Then you need at least 2 more years of plumbing work under a master plumber or someone with a similar license in another state.
- Without a journeyman certificate. You need at least 7 years of plumbing work under a master plumber (or equivalent out-of-state license), and you must pass the apprenticeship equivalency test, often called the Apprenticeship By-Pass Exam, before the board approves you for the master exam.
Your experience is proven with the board’s Verification of Employment form signed by your supervisor. If you can’t get that, the board may accept W-2s or an employer affidavit at its discretion. Self-employed time is documented with a Schedule C.
Exams
You need board approval before you can test. Once approved, the master exam is handled by the board’s testing vendor, ProV. You can test in person at Delaware sites or online with a remote proctor, by appointment. The passing score is 70%.
ProV’s Delaware candidate bulletin (dated 2022) lists the Master Plumber exam as 100 questions, 3 hours, open book, with a $100 exam fee. Allowed references listed there are the 2018 International Plumbing Code, the 2018 International Fuel Gas Code, and Plumbing Basics for Contractors (3rd edition). Check the current bulletin before you buy books.
If you fail, the board’s rules let you retake twice more without new approval. After 3 failed attempts you have to wait 1 year from your last attempt and reapply as a new applicant.
The By-Pass Exam for the 7-year route is handled separately. The board’s licensure page tells approved candidates to call New Castle County Vo-Tech, Polytech, or Sussex Tech to schedule, while the board’s exam page says Associated Builders and Contractors (ABC) Delaware administers it. Call the board to confirm where to register.
Fees and renewal
- Application fee: $173 (plumber), paid by card through DELPROS, non-refundable.
- Exam fee: paid to ProV ($100 per the 2022 bulletin).
- Temporary license: $40.
- Inactive status change: $45.
- Renewal fee: the board does not post a fixed amount. You are told the fee when you renew.
- Late renewal: an extra 50% of the renewal fee.
Licenses renew every 2 years and expire October 31 of even-numbered years. You can renew late for up to 1 year after expiration, but you can’t legally work until the renewal goes through. Miss that year and the license ends, so you would have to apply again as a new applicant. You can also ask to go inactive for up to 5 years.
Continuing education
Every renewal period, plumbers need 5 hours of board-approved CE, completed by October 31 of even years (starting with the 2026 cycle):
- 3 hours on code changes
- 1 hour on safety
- 1 hour on cross connections and backflow
If you hold both plumbing and HVACR licenses, you need 6 hours and alternate the code topic between plumbing and HVACR each cycle. New licensees get a break on the first renewal: under 1 year licensed means no CE, and 1 to 2 years means 3 hours. Extra hours don’t carry over, and repeating a course in the same period doesn’t earn more credit.
You attest to CE when you renew. Starting with 2026 renewals, the board randomly audits 5% of renewals, and everyone who renews late gets audited. Keep your certificates.
Bond, insurance, and business license
The plumbing law and board rules do not list a bond or insurance requirement for the Master Plumber license itself. Customers and general contractors may still ask for proof of insurance.
Running a plumbing business is a separate step. The Delaware Division of Revenue requires every contractor doing business in the state to get a Delaware business license, and it has separate resident and nonresident contractor rules, including bond forms for nonresident contractors. Contact the Division of Revenue for current fees and bond details. Any company offering plumbing also needs a licensed master plumber. If a company loses its only license holder, it has 7 days to notify the board.
Reciprocity
If you hold a current, good-standing license in a state with substantially similar standards, you can apply by reciprocity. The board currently lists Connecticut, Iowa, and Maryland as substantially similar, with no extra experience required.
For states the board lists as not substantially similar (Alabama, Arkansas, D.C., Florida, Georgia, Michigan, New Hampshire, New Jersey, North Carolina, Ohio, Rhode Island, South Carolina, Virginia, and West Virginia), you need at least 7 years of practice after getting that license. If your state isn’t on either list, send the board a copy of that state’s licensing law and rules to review.
How to apply
- Create an account in DELPROS, the state’s online licensing system.
- Pick the Master Plumber application and choose exam or reciprocity.
- Upload your journeyman certificate (if you have one) and your signed Verification of Employment forms or other proof of experience.
- Have every state where you’ve held a license send a verification directly to the board.
- Pay the $173 application fee by card.
- Wait for board review. The board meets monthly, and incomplete applications expire after 6 months.
- Once approved, take the By-Pass Exam if you’re on the 7-year route, then schedule the master exam with ProV.
FAQ
Does Delaware have a journeyman plumber license?
No. The state only licenses master plumbers. Journeymen and apprentices can work under a master plumber’s supervision, and a journeyman certificate from an approved apprenticeship shortens your path to the master exam.
Can I work in Delaware with my Maryland or New Jersey license?
Not without a Delaware license. Maryland is on the board’s substantially similar list, so you can apply by reciprocity. New Jersey is on the not substantially similar list, so you need 7 years of practice after licensure to qualify.
Is the master plumber exam open book?
Yes, according to ProV’s candidate bulletin. It’s timed, and only listed references are allowed.
Do I need a separate license for gas lines?
Plumbing services in Delaware include installing and connecting gas piping, so a Master Plumber covers it. Heating and cooling equipment falls under the HVACR licenses.
Next steps
Start by counting your supervised years and finding your journeyman certificate, since that decides your route. Then open a DELPROS account and download the Verification of Employment form. To compare Delaware with other states, see our plumbing license by state page, the full plumbing license guide, and the Maryland plumbing license page if you work both sides of the line. Ready to go out on your own? Read how to start a plumbing business.
