Iowa’s Master Plumber with Gas examination is administered through Kirkwood Community College, the board-approved examination provider for the Iowa Plumbing and Mechanical Systems Board. It is an open-book examination of 125 questions in six hours, passed at 75 percent, tested on the 2024 Uniform Plumbing Code together with the Iowa State Plumbing Code 2024 Amendment Booklet. This guide works through the credential, the examination, and the licensing route in the order a candidate meets them.
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The credential at a glance
| Item | Verified position |
|---|---|
| Program | Iowa Master Plumber with Gas: the master examination in the plumbing discipline |
| Regulator | Iowa Plumbing and Mechanical Systems Board, within the Iowa Department of Inspections, Appeals, and Licensing, under Iowa Code chapter 105 and 481 IAC chapters 425–435 |
| Examination provider | Kirkwood Community College, the board-approved examination provider. There is no PSI bulletin for Iowa plumbing |
| Examination structure | Single written, proctored examination, delivered in person or online; open book |
| Size and time | 125 questions in 6 hours |
| Passing standard | 75 percent — a score of 75 percent or better is passing under 481 IAC 429.6(2)d |
| Tested references | 2024 Uniform Plumbing Code and the Iowa State Plumbing Code 2024 Amendment Booklet — the only two references allowed during the exam |
| Fees, kept distinct | $119 Kirkwood examination fee per attempt, payable to Kirkwood; plus a separate $35 board examination application fee per trade examination under 481 IAC 428.1(4) |
| License term and renewal | Three years; master initial and renewal fees of $240 in rule; eight hours of continuing education per term for a single license |
| Administrator note | PassProfessor is independent and is not affiliated with the Iowa Plumbing and Mechanical Systems Board, the Iowa Department of Inspections, Appeals, and Licensing, or Kirkwood Community College |
Iowa rewards the candidate who reads its system in layers. The statute, Iowa Code chapter 105, creates the licensing structure. The Board’s rules in agency 481 of the Iowa Administrative Code operate it — chapter 425 adopting the plumbing code, chapter 428 setting fees, chapter 429 governing application and examination, chapter 432 governing continuing education. The provider layer, Kirkwood Community College, delivers the examination the Board has approved it to conduct. Almost every Iowa error available to a candidate consists of looking for a fact on the wrong layer: a fee in the wrong chapter, a PSI bulletin that does not exist for this program, or a code edition from a superseded adoption.
First, correct the record: who examines Iowa plumbers
Secondary material about Iowa plumbing examinations is unreliable at its most basic point — the identity of the examiner. The verified position is this: examinations are conducted through Kirkwood Community College, the Board’s approved examination provider, under contract to conduct the examination program. Board approval comes first. A candidate files the state Examination Candidate Application, receives an Exam Approval Letter, and only then registers with Kirkwood.
There is no PSI Candidate Information Bulletin for Iowa plumbing, and PSI does not administer this program. The PSI Iowa bulletin that does exist belongs to the Iowa Electrical Examining Board, a different credential in a different trade. Advice that sends an Iowa plumbing candidate to a PSI bulletin, a PSI portal, or PSI scheduling is advice about somebody else’s examination. The functional equivalent of a bulletin for this program is Kirkwood’s State Disciplines page, which prints the examination header, the outline, the reference rules, and the fee list used throughout this guide — without a copyright year, revision date, or bulletin number, none of which this guide invents for it.
Two more secondary figures must be set aside at the start. A time of five hours and a fee of $109 for the master examination circulate in vendor material. Both are rejected against the primary sources: the master examination runs six hours, and the Kirkwood examination fee is $119. A candidate budgeting time or money from the secondary figures will under-budget both.
The code question, settled: tested equals adopted
Iowa is the straightforward case, and the guide states it without hedging because candidates waste real preparation time when it is hedged. The State Plumbing Code at 481 IAC 425.1 adopts Sections 101 and 102, Chapters 2 to 17, and Appendices A and M of the Uniform Plumbing Code, 2024 Edition, with Iowa amendments, effective March 26, 2025. The examination’s tested references are the 2024 Uniform Plumbing Code and the Iowa State Plumbing Code 2024 Amendment Booklet. The code in the field and the code in the room are the same code.
Three consequences follow. The first is edition discipline: study material keyed to the 2018 or 2021 Uniform Plumbing Code is background reading, not examination preparation, wherever the 2024 text differs. The second is amendment discipline: the Amendment Booklet is not an optional supplement. It is one of only two references allowed in the room, and the provider states that the outline reference lists are the references used to develop the exams. The third is a specifically Iowa trap — the state replaces the Uniform Plumbing Code trap-arm table with its own table in the adopted code. A trap-arm answer taken from the model-code table can be a correct model-code answer and a wrong Iowa answer on the same facts.
The provider adds one nuance, quoted here in substance because candidates misread it in both directions: although exam questions are based off information from a certain book edition, references brought to the exams can be from any edition. The permission concerns what may be carried into the room. It does not change what the questions are based on — the 2024 edition. A candidate who brings an older edition has accepted a translation task on every changed provision, under a clock, for no benefit.
Fuel gas sits inside this structure, not beside it. The “with Gas” in the examination title reflects Chapter 12 of the 2024 Uniform Plumbing Code: fuel gas piping must comply with that chapter unless Iowa Code chapter 661, chapter 226 conflicts, in which case chapter 226 governs. No standalone NFPA 54 volume is listed for the plumbing examinations, and neither is a mathematics book or an OSHA volume. Those books appear on reference lists for other Iowa examinations in the same provider material — HVAC, hydronics, mechanical, and sheet metal among them — and their presence there is precisely why candidates must read the plumbing list on its own terms rather than borrow a neighbouring trade’s list.
The examination, section by section
The master examination is a single sitting: open book, 125 questions, six hours. Kirkwood publishes its content outline as percentages of the paper, not as fixed per-topic question counts, and no fixed counts are printed anywhere in this guide — multiplying a percentage by 125 produces arithmetic, not a published fact, and pacing a sitting by derived counts the provider never stated is a self-inflicted error.
Chapter 3, General Regulations — 5 percent. The general provisions that frame installation work across the code. Small in weight, but the chapter other chapters assume the candidate already holds.
Chapter 4, Fixtures and Fittings — 8 percent. Fixture requirements, counts, and installation, with the fittings that connect fixtures to the systems behind them.
Chapter 5, Water Heaters — 5 percent. Water heater installation and its protective requirements. A compact area that candidates routinely over-weight because the material feels familiar from field work.
Chapter 6, Water Supply and Distribution — 11 percent. The supply side in depth: distribution systems and the sizing reasoning that decides whether a design delivers. The third-heaviest area of the paper.
Chapter 7, Sanitary Drainage — 18 percent. Jointly the heaviest area. Drainage systems are examined at master depth — the candidate is expected to reason about a whole system, not to recall isolated fittings.
Chapter 8, Indirect Wastes — 5 percent. Indirect waste piping and the air-gap and air-break protection that separates waste from supply.
Chapter 9, Vents — 18 percent. Equal in weight to sanitary drainage, and the natural partner to it: drainage and venting together carry more than a third of the entire examination. This is the centre of gravity of Iowa master preparation, and study time should be allocated as if it were.
Chapter 10, Traps and Interceptors — 5 percent. Traps and interceptors — the area where Iowa’s own trap-arm table replaces the model-code table, and where amendment discipline is tested most directly.
Chapter 11, Storm Drainage — 10 percent. Storm and roof drainage: a substantial area, twice the weight of several chapters candidates treat as major.
Chapter 12, Fuel Gas Piping — 7 percent. The gas content of the “with Gas” title, examined as code work under Chapter 12 and the chapter 226 conflict rule described above.
Isometric — 8 percent. Isometric reading and analysis. Two things must be held together here. It is a genuine written content area, weighted more heavily than water heaters, indirect wastes, traps, or fuel gas. And it is distinctly master-level: the journeyperson outline published by the same provider has no Isometric cell at all. But it is not a separate drawing examination, and this examination has no hands-on practical: the examination in rule is written and proctored, and no source describes a practical component. A candidate prepares for isometric questions on paper, not for a bench exercise or a drawing sitting.
Sitting mechanics: books, delivery, and the score
The reference rules decide sittings, so they are stated in full. Only the two listed references — the 2024 Uniform Plumbing Code and the Iowa State Plumbing Code 2024 Amendment Booklet — may be used. References may be bound or loose-leaf; photocopies may not be used. Highlighting and permanent tabbing completed before arrival are allowed; Post-it notes are not allowed. Books may not contain handwritten or additional notes. References may not be shared, and they are checked before and after the examination. The practical reading of those rules is that book preparation is part of examination preparation: a permanently tabbed, highlighted, 2024-edition code and Amendment Booklet, organised by chapter in the outline’s order, is equipment as real as any tool the candidate owns.
Delivery is written and proctored, conducted in person or online, and offered periodically at rotating Iowa sites — sixteen test cities are listed by the provider. At the end of the sitting the score is shown on screen as a percent correct: 75 percent or above passes. Results are confidential to the applicant and the Board. The examination is not subject to review, but the vendor will identify failed sections on request, which converts a failure into a specific study list keyed to the outline areas above.
Eligibility and the ladder beneath the master license
The master examination sits on top of a journeyperson foundation in either of two forms. The candidate has previously been licensed as a journeyperson in the discipline and holds at least two years of journeyperson work experience in the discipline; or the candidate has previously been licensed as master in the applicable discipline in another state or local jurisdiction. The two-year figure is a rule-layer requirement, stated in 481 IAC 429.6 alongside the Department’s examination page; the statute requires application, fees, a passing score on the state master examination, and evidence of prior journeyperson or master licensure in the discipline. Every license applicant, on any route, must be at least 18 years old.
For context beneath this rung: the journeyperson examination in the same discipline is itself a Kirkwood-administered, open-book sitting tested on the same two references, at 75 questions in three hours with the same 75 percent standard and the same $119 Kirkwood fee. The master candidate has therefore already passed through this examination system once — same provider, same books, same pass mark — at a smaller size, a shorter clock, and without the isometric area. What changes at master level is scale, depth in drainage and venting, and the expectation of system-level judgement.
Timing rules govern the approach to the sitting. The examination application must be submitted at least 15 business days before taking an examination. Eligibility and approval are valid for one year, and within that year the candidate may test as many times as necessary, paying the Kirkwood fee for each attempt. When the year runs out, the route restarts at the application: a new application and a new $35 board examination application fee. After success, a second clock starts — a passing score expires if licensure is not applied for within two years of passing notification — and a license is not automatically issued on passing. Passing the examination and holding the license are two separate events, and the second must be affirmatively completed.
Fees, stated by layer and never merged
Iowa charges for this examination twice, by two different parties, for two different steps, and this guide keeps them apart because candidates and secondary sources alike merge them.
The Kirkwood examination fee is $119 for the Master Plumber with Gas examination. It is a provider-layer fee: non-refundable, non-transferable, payable to Kirkwood, and payable again for each attempt. The law fact base for this program notes that no Department page or rule states this dollar figure — it is verified at the provider layer and is cited here as a provider fee, never as a rule fee.
The board examination application fee is $35 per trade examination. It is a rule-layer fee, set at 481 IAC 428.1(4) and stated on the Department’s examination page. It belongs to the approval step that precedes Kirkwood registration.
Beyond the examination, the rule-layer license fees are $240 for the initial master license and $240 for renewal, each covering the three-year term, with initial licenses issued for less than three years prorated at a one-sixth deduction per six-month period. Where a combined license is issued in a single transaction, the combined fee is the sum of the separate fees reduced by 30 percent. All fees in the system are nonrefundable.
The license after the pass: term, renewal, and continuing education
All licenses in this system expire June 30 every three years, and renewal is due at least 30 days before expiration. Renewal is without examination. The late ladder is graduated and short: renewal on or before July 31 carries no late fee; renewal during August carries a $60 late fee plus the renewal fee; renewal after August 31 and through the following June 30 carries a $100 late fee plus the renewal fee. The ladder is an argument for renewing in June, stated in dollars.
Continuing education runs with the term. It applies to each active or inactive master licensee, with the compliance period running from the license issue date to its expiration date. For a single license the requirement is eight hours per three-year term, divided by the rule into named parts: two hours of Safety, covering Iowa OSHA Act content; two hours of Code, covering the Iowa plumbing code for a plumbing license; and four hours of Discipline content. A licensee holding multiple licenses completes four hours of Safety and eight hours of Discipline, with the Code hours unchanged — for a plumbing-plus-mechanical holder that arithmetic totals sixteen hours, a derived total the rule’s components produce rather than a figure the rule prints as a single number. Up to one-half of the continuing education may be completed in computer-based or online form.
Retakes, without invention
The retake rules are short because the sources are short, and this guide does not lengthen them. A candidate who does not pass must register and pay for a new exam with Kirkwood. No waiting period between attempts is stated in any primary source. No numeric retake cap exists in the statute — which provides that a failing applicant shall be allowed to retake the examination at a future scheduled time — or in rule 429.6. The real constraints are structural: the one-year approval window, the per-attempt fee, and the discipline of using the vendor’s failed-section identification to rebuild the specific outline areas that failed rather than re-reading the entire code. Any source that states an Iowa retake cap or a cooling-off period is stating something the statute and rule do not contain.
A study plan built on the outline’s actual weights
Start with the centre of gravity. Sanitary drainage and vents, at 18 percent each, come first and receive the largest share of total study time, studied together as one system rather than as two chapters in sequence. Build the supply and storm work next — water supply and distribution at 11 percent and storm drainage at 10 percent — where sizing reasoning carries the marks. Then work the middle band deliberately: fixtures and fittings and the isometric area at 8 percent each, and fuel gas piping at 7 percent, with the isometric practice done as written questions under time, in the form the sitting actually uses. Close with the 5 percent chapters as a group — general regulations, water heaters, indirect wastes, and traps and interceptors — while giving traps the extra pass its Iowa amendment demands: every trap-arm figure checked against Iowa’s own table, never against the model code’s.
Prepare the books as equipment. Before the final study weeks, the code and the Amendment Booklet should already be in their examination condition: 2024 edition, permanently tabbed by chapter, highlighted in advance, free of handwritten notes and loose inserts the rules exclude. Retrieval drills — question first, chapter located against the clock — belong in the plan from the middle onward, because an open-book sitting examines retrieval speed as surely as it examines knowledge. Finish with full-length timed practice at the real parameters: 125 questions, six hours, only the two permitted references in the room, so that pacing, book handling, and endurance are rehearsed together rather than discovered separately on the day.
The errors this examination is built to catch
Looking for a PSI bulletin. There is none for Iowa plumbing; the examiner is Kirkwood under Board approval, and the electrical board’s PSI material is a different trade’s document. Budgeting from secondary figures. Five hours and $109 are both wrong; six hours and $119 govern, and the $35 board fee is additional and separate. Studying the wrong edition. The questions are keyed to the 2024 Uniform Plumbing Code; permission to carry another edition into the room is not permission to answer from it safely. Answering trap-arm questions from the model code. Iowa replaced that table; the Amendment Booklet and the Iowa text govern. Borrowing another trade’s reference list. NFPA 54 and the other volumes listed for Iowa mechanical examinations are not plumbing references for this sitting. Deriving question counts from percentages. The provider publishes percentages only; a study plan built on invented per-topic counts misallocates the very time the percentages were published to allocate. Treating a pass as a license. Licensure must still be applied for, within two years of the passing notification, or the score expires.
Iowa in one view
Iowa in one view is a tidy system that punishes untidy sourcing. One board, inside one department, under one licensing chapter. One approved provider, and no vendor bulletin from any other company. One code edition that is simultaneously the adopted field code and the tested code, with the state’s amendments carried into the room as a named second reference. One sitting — 125 questions, six hours, open book, 75 percent — whose outline tells the candidate exactly where its weight sits: drainage and venting first, supply and storm work next, gas inside the plumbing code rather than beside it, and isometric judgement reserved for the master tier. A candidate who keeps the layers straight — statute for structure, agency 481 rules for operation, Kirkwood for delivery, and the two permitted books for answers — will find that Iowa has hidden nothing. Every consequential fact about this examination is published; the work is reading it where Iowa actually put it.
The companion program page, Iowa Master Plumber with Gas Exam Preparation, summarises the PassProfessor program built on this guide’s facts. The program is in the works and enrollment is not yet open; leave an email address below and PassProfessor will write to you when it is ready — and only about this program.
Frequently asked questions
Is there a PSI bulletin for the Iowa plumbing examinations?
No. Kirkwood Community College is the Board’s approved examination provider for Iowa plumbing. The PSI Iowa bulletin that exists covers the Iowa Electrical Examining Board, a different credential.
What are the master examination’s size, time, and pass mark?
125 questions, 6 hours, open book, with a score of 75 percent or above required to pass. Secondary figures of five hours are superseded.
Which books may I use in the room?
Only the 2024 Uniform Plumbing Code and the Iowa State Plumbing Code 2024 Amendment Booklet. Bound or loose-leaf copies are allowed; photocopies, Post-it notes, handwritten notes in the books, and sharing are not.
My code book is an earlier edition. May I bring it?
The provider states references brought to the exams can be from any edition, but the questions are based on the 2024 edition. Answering changed provisions from an older edition is the candidate’s risk.
How much does the examination cost in total?
Two distinct fees: $119 to Kirkwood for the examination, per attempt, and $35 to the Board per trade examination application. The $109 figure in secondary material is superseded.
Does the master examination include a practical?
No hands-on practical is described in any source. The examination is written and proctored. Isometric content is a written area at 8 percent of the outline, present on the master outline and absent from the journeyperson outline.
What experience must a master candidate hold?
Prior licensure as a journeyperson in the discipline plus at least two years of journeyperson work experience in the discipline, or prior master licensure in the discipline in another state or local jurisdiction. Applicants must be at least 18.
How many times may I test on one approval?
As many times as necessary within the one-year approval validity, paying the Kirkwood fee each attempt. No waiting period and no numeric cap are stated in the statute or rule. After the year, a new application and a new $35 board fee are required.
Does passing the examination issue my license?
No. Licensure must be applied for separately, and a passing score expires if licensure is not applied for within two years of passing notification.
What continuing education does renewal require?
Eight hours per three-year term for a single license: two hours Safety on Iowa OSHA Act content, two hours Code on the Iowa plumbing code, and four hours Discipline. Up to one-half may be completed online.
When does enrollment open for the PassProfessor program?
The program is in the works and enrollment is not yet open. Leave an email address on this page and PassProfessor will write to you when the program is ready — and only about this program. See also the Iowa Master Plumber with Gas program page.