The Delaware Master Plumber Guide

What the Delaware Master Plumber License Authorizes

In Delaware, the Master Plumber license covers more than the plumbing systems most tradespeople think of first. The credential authorizes you to design, install and repair water-supply systems and liquid/waste-carrying systems — the potable water distribution, drainage and venting work at the core of the trade — and to install and connect gas piping. That gas scope is what sets Delaware's exam apart from a pure plumbing test: the state folds fuel gas work into the same license, and the exam follows.

This is why the exam is a combined plumbing and fuel gas exam. It is not plumbing with a gas question or two tacked on as an afterthought — fuel gas content carries its own subject area (10 of 100 questions) and the International Fuel Gas Code (IFGC) 2018 appears on Delaware's list of permitted references right beside the International Plumbing Code (IPC) 2018. If you prepared for a plumbing-only exam in another state, budget real study time for gas pipe sizing, venting and appliance connection rules before you sit in Delaware.

The exam is regulated by the Delaware Division of Professional Regulation and administered on its behalf by ProV, Inc (provexam.com), which publishes the Candidate Information Bulletin (CIB) for the program. Within ProV's Plumbing & HVACR category, Delaware lists the Master Plumber exam — there is no separate journeyman plumber exam line delivered by ProV in that category. For Delaware candidates, the master exam is the licensing exam.

You are already an experienced plumber — this is the step from installing under supervision to owning the design, code-compliance and gas-connection decisions on a job. The exam assumes real field knowledge before it tests master-level judgment on top, which is why the blueprint leans so heavily on drainage and vent systems, water supply and distribution, and the code-navigation skill an open-book exam rewards.

Eligibility: The Division of Professional Regulation Comes First

Delaware does not let you register for the master exam on your own. The Delaware Division of Professional Regulation governs plumber licensing in the state and controls who is eligible to sit — ProV administers the test, but the state decides who may take it:

• State requirements first: confirm the current eligibility requirements — experience, education, licensure status and documentation — set by the Delaware Division of Professional Regulation for the Master Plumber license.
• Application and review: submit your application through the Division's process and let the state evaluate your credentials against the rules in effect when you apply.
• Then the exam: once the Division approves you, you schedule the ProV exam and pay the $100 exam fee.
• Confirmation: the eligibility standard is set by the Division of Professional Regulation, not by the exam vendor — contact the Delaware Division of Professional Regulation for current eligibility requirements and application instructions.

Do not buy prep or book a test date before you have confirmed your eligibility with the Division. The approval is the gate that everything else hangs on — and with a 3-attempt cap per application, you do not want to burn an attempt on paperwork timing you could have sorted out first.

Exam Format: 100 Questions, 180 Minutes, Open Book and Timed

The Delaware Master Plumber exam is a single, computer-based session delivered by ProV:

• 100 questions in 180 minutes. Three hours for the full combined plumbing and fuel gas exam — about 1.8 minutes per question, which is where code-lookup speed becomes the difference-maker.
• 70% passing score. You need 70 of 100 questions correct to clear the line.
• Open book and timed. The bulletin states plainly that all exams are open book and timed, and the listed reference books may be used during testing.
• Permitted references only. The International Plumbing Code (IPC) 2018, the International Fuel Gas Code (IFGC) 2018 and Plumbing Basics for Contractors, 3rd edition (2014) are the references the bulletin lists for this exam.
• In person or at home. ProV delivers the exam at test centers in Dover and two Wilmington locations, or at home through ProV Examroom.

Read the open-book rule twice, because it changes how you study: this is a bring-your-knowledge-of-the-books exam, not a memorization exam. With the IPC and IFGC in front of you, the questions test whether you know where the answer lives — which chapter, which section, which table — and how fast you can get there. The clock and the tabs are the real test.

Official Subject Areas (100 Scored Items)

The Candidate Information Bulletin publishes the subject-area breakdown for the 100 questions. Study time should track these weights:

The pattern is unmistakable: General Knowledge (16) is the single heaviest subject, and with Drain/Waste & Vent Systems (14) and Water Supply and Distribution (14) the top three together account for 44 of the 100 questions — nearly half the exam. The next tier is Water Heaters (10) and Fuel Gas Systems (10); the five heaviest columns are worth 64 questions combined. Master those first, then round out the 6–8 question areas: Isometrics & Plan Reading (8), Plumbing Math (8), Fixtures & Fittings (8), Storm & Roof Drainage (6) and Safety (6). The fuel gas column matters more here than in most states because Delaware's license — and exam — are combined plumbing and fuel gas by design.

Permitted References: The Books at Your Station

The bulletin lists exactly three references that may be used during testing. Own the listed editions — check the ISBNs, not just the titles — and learn their layout:

Because the exam is open book, preparation is not about memorizing the codes — it is about navigating them under a clock. Learn the chapter map of the IPC and IFGC 2018 editions, mark the tables you use most (drainage fixture units, vent sizing, pipe sizing, gas sizing), and drill index-first lookup until finding a section is a reflex.

Fees, Retakes & Attempt Limits

• Exam fee: $100 per exam.
• Practice exams: $25 through the testing program.
• Retakes: a retake is permitted after a 7-day wait from your previous attempt.
• Attempt limit: Plumbing & HVACR candidates are limited to 3 testing attempts per application. After three attempts, you face a one-year wait and must submit a new application to test again.
• Vendor: exams are delivered by ProV, Inc (provexam.com) for the Delaware Division of Professional Regulation, in person (Dover and two Wilmington centers) or at home via ProV Examroom.

The 3-attempt cap changes how you should approach this exam. There is no “I will just retake it” luxury — every sitting draws down a limited budget, and exhausting it means a year off before you can apply again. Treat each attempt as a full 100-question, 180-minute performance prepared against the entire blueprint, and do not schedule until your timed practice scores sit comfortably above 70%.

How to Prepare

1. Confirm your Division eligibility first. Get your eligibility confirmed with the Delaware Division of Professional Regulation before you invest in prep or book a date. With a 3-attempt cap, the gate matters more than ever.
2. Build the exact reference library. Buy or borrow the listed editions — IPC 2018, IFGC 2018, Plumbing Basics for Contractors, 3rd edition (2014) — by ISBN. Study with the same books you will test with, and learn where every answer lives in them.
3. Train the code map, not just the code. Delaware hands you open books and a 1.8-minutes-per-question clock. Drill chapter navigation, table location and index speed in both codes. Know where vent sizing, drainage fixture units, water pipe sizing, water heater requirements and gas pipe sizing tables sit before you worry about memorizing numbers.
4. Drill the heavy columns first. General Knowledge (16), Drain/Waste & Vent Systems (14) and Water Supply and Distribution (14) are 44 of 100 questions. Get those to exam-day speed before Water Heaters (10), Fuel Gas Systems (10) and the 8-question tier.
5. Practice plan reading and isometrics. The Isometrics & Plan Reading area (8 questions) rewards plumbers who can read riser diagrams and isometric drawings and connect what a plan shows to the code requirement it triggers. Work drawing-based questions, not just text-based ones.
6. Do the math by hand, then against the tables. Plumbing Math (8 questions) plus the calculation work buried in DWV, water supply and fuel gas covers fixture-unit totals, sizing and slope. Practice the arithmetic cleanly and confirm every result against the IPC and IFGC tables.
7. Cover the fuel gas scope. This is the area most plumbing-only candidates under-prepare. Work the IFGC 2018 chapter by chapter: gas piping, venting, appliance connections and pressure testing, with the sizing tables under your hand.
8. Simulate under real conditions. Full-length, timed, open-book runs — 100 questions in 180 minutes with the references in front of you — at least weekly in the final month, aiming comfortably past the 70% line. In-person and at-home delivery feel different; rehearse whichever you plan to use.

MasterPlumberPractice is built for exactly this kind of exam: code-referenced practice questions aligned to the open-book IPC blueprint, full IPC theory guides, and an AI tutor that explains requirements in plain language with the exact code references. Our timed simulations replicate the open-book, code-navigation format so the real exam feels like a repeat. For the Fuel Gas Systems column, pair that practice with the IFGC 2018 chapter map — the two together cover the full Delaware scope. Start with free IPC practice questions to feel the format, and create a free account to track your scores as you go.

Frequently Asked Questions

Ready to Earn the Delaware Master License?

The Master Plumber license is the credential that lets you take full responsibility for plumbing and gas piping work in Delaware — and with a 3-attempt cap per application, preparation quality is not optional. Start with the official blueprint: learn the code with our open-book IPC theory guides, try free Delaware-style practice questions, register free and see the all-inclusive pricing — one subscription covering timed simulations, the full theory library and the AI tutor, so you never buy subject-area prep piece by piece. Pair it with the IFGC 2018 to close out the fuel gas column, and walk into ProV ready for all 100 questions.

This guide reflects the ProV Inc Candidate Information Bulletin for the Delaware Division of Professional Regulation (verified September 7, 2026). Requirements, fees and rules can change — confirm the current bulletin and the Division's eligibility requirements before you schedule.