About this C-42 — Sanitation System prep
This prep is built specifically for the C-42 — Sanitation System examination and includes a 19,000+-word study guide written for this exam, 5 full-length practice exams and 500 practice questions, each with a written explanation.
The C-42 Sanitation System trade examination is administered by CSLB / PSI. Closed book. 100 Q / 210 min. Pass % not published. Mix on/after 6/1/2023: Planning 27, New Septic 26, Sewer Lateral 10, Septic Maintenance 10, Safety 27. C42StudyGuide.pdf. Not C-36. Not Law 115/73.. This prep is written to that board’s current scope, not to a generic national syllabus.
The real C-42 — Sanitation System exam contains 100 questions. Our practice exams mirror that structure so the format is familiar before you sit it.
Topics covered
- How this guide works
- Planning and Estimating — 27% of the exam
- New Septic System Installation — 26% of the exam
- Key Regulatory References
- Study Tips and Exam Preparation
- Key Code Sections the Exam Tests
- CPC Drainage Sizing, Fittings, Testing and Component Standards
- How C-42 — Sanitation System is actually scored
- California — who writes C-42 — Sanitation System
- Plumbing method on C-42 — Sanitation System
- Clock discipline for C-42 — Sanitation System
- C-42 last-mile on-syllabus topics
- Sewer Lateral Installation and Repair — 10% of the exam
- Practice Exam Questions
- Septic System Maintenance and Repair — 10% of the exam
- C-42 sitting recap \u2014 C42StudyGuide.pdf on/after June 1, 2023
- Safety — 27% of the exam
- Business & Law — tested on a separate exam
- Code reference and general knowledge
How access works
You are paying for access length (30, 60, or 90 days). The study guide and four timed exams are the same on every term. Access starts when you enrol and works on any device for that term.
Not affiliated with or endorsed by any state licensing board or exam vendor. For exam-preparation purposes only.
What is actually on the C-42 exam
CSLB divides the Sanitation System (C-42) examination into five sections. These weightings are the Board’s own, taken from the study guide it publishes for this classification — they are not our estimate:
| Section | Share of exam |
|---|---|
| Planning and Estimating | 27% |
| New Septic System Installation | 26% |
| Sewer Lateral Installation and Repair | 10% |
| Septic System Maintenance and Repair | 10% |
| Safety | 27% |
The C-42 examination is closed book — no reference materials may be used during the test. Questions are multiple choice with four options, and there is no penalty for guessing, so leave nothing blank.
This is only half of what you sit. Every applicant also passes the separate Law and Business examination, which is not part of the C-42 paper and is weighted on its own outline. Budget preparation time for both.
Source: CSLB Sanitation System (C-42) examination study guide. Contractor Pathway is an independent exam-preparation provider and is not affiliated with or endorsed by CSLB.