No. The C-36 plumbing exam in California is entirely closed-book, and you cannot bring the California Plumbing Code, any reference materials, notes, or study guides into the exam room. The CSLB and PSI Services, the exam vendor, enforce this rule strictly at every testing centre across California.
This is a hard rule because the exam measures your knowledge, not your ability to look things up under time pressure. You need to know the code, calculations, and standards from memory. That is the entire point of the exam—to prove you have the technical knowledge to design and install plumbing systems safely and legally.
Key facts
| Fact | Value | As of | Source |
|---|---|---|---|
| Exam type | Closed-book, no reference materials | 2026-09-23 | CSLB exam policy |
| Calculator allowed | Yes, non-programmable only | 2026-09-23 | PSI Services exam rules |
| Photo ID required | Yes, government-issued | 2026-09-23 | PSI Services exam rules |
| Exam proctor | PSI Services | 2026-09-23 | CSLB contractor exam administration |
| Penalty for contraband materials | Test cancellation and exam fee forfeited | 2026-09-23 | PSI Services exam administration rules |
What you can bring to the exam room
When you arrive at the PSI testing centre on exam day, you can bring only three things:
A valid government-issued photo ID. This is required to verify your identity before you enter the exam room. The ID must be current and match the name on your exam registration. A driver's license, passport, or military ID works. No ID, no exam—the proctor will turn you away. One non-programmable calculator. You can bring a basic four-function or scientific calculator, but it cannot have programming capability, stored formulas, or the ability to access external data. Many candidates bring a Casio FX-260 or similar basic scientific calculator. The proctor may inspect it to confirm it is not programmable. Leave it in a clear plastic bag so it can be checked quickly. Nothing else. No books, no notes, no phone, no smartwatch, no water bottle, no bag, no pen (the centre provides writing tools). Your car keys and personal items stay in a locker outside the exam room.Why can you use a code book on the C-36 exam? You cannot.
Many candidates ask whether the California Plumbing Code will be available during the exam, or whether you can bring a marked-up copy. The answer is no to both. The CSLB and PSI do not provide the code at the testing centre. You will not see a copy of the California Plumbing Code, any code section references, or any reference material on screen or on paper during the exam.
This forces you to memorize the critical sections before test day. That is harder than it sounds, because the exam covers:
- Drainage and venting system design (CPC Sections 403, 701)
- Water supply system design and sizing (CPC Section 422)
- Fixture connection and rough-in standards (CPC Sections 405, 406, 407)
- Backflow prevention and safety devices (CPC Section 608)
- Inspection and testing procedures (CPC Section 408)
- Trap sizing, slope, and vent stack calculations
- Fixture unit demand and simultaneous demand load math
- Specific dimensions for rough-ins, clearances, and spacing
What the exam actually tests
The C-36 exam is 100 multiple-choice questions. You have four hours to complete it. About 60 percent of the questions test knowledge of the California Plumbing Code. The rest test trade knowledge, safety, and practical problem-solving—things like sizing a drainage system for a three-story building, calculating water supply demand, or identifying why a vent system fails an inspection.
Because you cannot reference the code during the exam, the questions are written to test whether you can apply code rules to real-world scenarios without looking them up. For example:
A 4-inch building drain serves a residential home with 15 fixture units of drainage load. The drain has a 1/4-inch-per-foot slope and connects to a 4-inch municipal sewer. Under CPC Section 403, is this installation code-compliant?You need to know that a 4-inch drain at 1/4-inch slope handles 160 fixture units, so yes, it is compliant. You cannot flip through the code to find Table 403.2 during the exam. You need the answer in your memory.
How to prepare for a closed-book exam
Because you cannot bring the code book into the exam room, your preparation strategy must focus on memorization and comprehension, not just reading. This is different from how many plumbers study for other certifications that allow open-book testing.
Here is what works:
Use active recall, not just reading. Read a code section once, then close the book and write down what you remember. Check your answer. Repeat until you can recall the key numbers and rules from memory. Make study cards for critical numbers. Trap arm length, vent stack sizes, relief valve settings, water heater installation heights, backflow device locations. Put the number on one side, the rule on the other, and quiz yourself daily for two weeks before the exam. Work practice exam questions under timed conditions. This trains your brain to retrieve information quickly, which is what you will need to do during the four-hour exam. Take full-length practice exams the same way you will take the real exam: no code book, calculator only, four hours, no breaks in the middle of a section. Study the sections the exam weights most heavily. Drainage and venting (CPC Section 403) and water supply (CPC Section 422) together make up about 40 percent of the exam. Spend the most time memorizing the tables, calculations, and design rules for those sections. Learn the math cold. Fixture unit calculations, demand load, slope, vent sizing, and pressure drop math appear on almost every exam. You cannot do these problems without a calculator, but you need to understand the formulas and when to use them without looking anything up. Practice the same calculation problems 20 times so the approach becomes automatic.What happens if you bring a code book into the exam room
If a proctor sees you with a code book, notes, or any reference material, your exam will be canceled immediately. You will not be allowed to finish the exam. Your exam fee will be forfeited, and you will have to pay the full fee again to retake it. You may also face a report to the CSLB, which could affect your contractor license application down the road.
The testing centres have no discretion on this. The rule is absolute, enforced by PSI Services across all CSLB exams in California.
Common questions
Can I bring a marked-up or highlighted California Plumbing Code to the exam?
No. You cannot bring any version of the California Plumbing Code, marked up or not. No highlighter marks, no tabs, no sticky notes, no annotations. The code in any form is not allowed in the exam room.
What if I need to look up a code section during the exam?
You cannot. The exam is closed-book by design. If a question asks about CPC Section 403 requirements for vent sizing, you need to know the answer from memory. If you do not know it, you make your best guess and move on. There is no way to reference the code during the exam, and using any reference material is grounds for immediate test cancellation.
Is a calculator the same as a code book in terms of what is allowed?
No. A calculator is explicitly allowed. A non-programmable calculator is a tool you use to perform math during the exam, such as fixture unit demand calculations or pipe sizing. A code book is reference material, which is prohibited. You can use the calculator freely; you cannot use reference materials at all.
Can I bring water, snacks, or my phone into the exam room?
No. You can bring only your photo ID and your calculator. Water, snacks, bags, phones, smartwatches, and all personal items must stay in a locker outside the exam room. The testing centre may have a break area where you can eat or drink between exam sections, but most candidates complete the exam in one sitting without a break.
What should I study if I cannot use the code book during the exam?
Focus on memorizing the key numbers, tables, and rules from the California Plumbing Code and from the trade standards the exam covers. Study the fixture unit tables, trap arm length limits, vent stack sizing, water supply demand calculations, backflow prevention rules, and inspection procedures. Take practice exams under closed-book conditions to train yourself to answer questions from memory in the time available.
Will the exam give me any reference information, like a table or formula sheet?
No. The exam is presented on a computer screen with no reference materials, tables, or formula sheets provided on screen or in print. Everything you need to answer the questions must come from your own knowledge and your calculator. This is why closed-book preparation is so important.
Sources
- CSLB — Contractor Licensing Exams — exam format, rules, and administration policy for C-36 plumbing contractor license
- PSI Services — Exam Administration Rules — testing centre protocols, materials allowed, and proctor enforcement standards for California contractor exams
- California Business and Professions Code Section 7068 — contractor license classification and exam requirements
- California Plumbing Code Sections 403, 405, 406, 407, 408, 422, 608 — code requirements tested on the C-36 exam