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how to pass your C-42 license for sanitation systems contractors in California

Pass Your C-42 License Test In 5 Steps!

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Passing the C-42 license test on your first try can actually be harder than you think, but if you follow these steps it can be easy.

In California, thousands of sanitation workers apply for the C-42 license each year.

a large sanitation treatment plant. Sanitation contractors applying for the C-42 license should know these 5 steps

The Contractor State License Board offers 73 different classifications.

Read this to see if you qualify to get an exam date.

I have helped thousands of people pass the exam on their first try, and these 5 Quick tips are based on the information I have gathered over the years that I know works.


1. Know What Is Going To Be On The C-42 License Test

Preparation is everything, many tradesmen I work with apply for the exam without actually knowing what will be on the test.

Taking the time to look at some basic information about the exam is very helpful.

The exam for sanitation contractors includes:

  • 115 Questions LAW
  • 115 Questions Sanitation Systems
  • Multiple Choice Exam
  • Close Book
  • 3 Hours To Complete Each Section
  • Taken On A Computer at A State Testing Center


Law & Business

  • Business Organization
  • Business Finances
  • Employment Requirements
  • Contract Requirements and Execution
  • Licensing Requirements
  • Safety 
  • Public Works

Sanitation Systems

  • Planning and Estimation (27%)
  • New Septic System Installation (26%)
  • Sewer Lateral Installation and Repair (10%)
  • Septic System Maintenance and Repair (10%)
  • Safety (27%)

For a complete guide to the Contractor License LAW concepts, you must know to pass the C-42 license test.


2. Take C-42 License Practice Tests

a contractor with a large tube going into the ground

While running a contractor license school, I learned that the biggest difficulty my students faced was that most of them had not taken an exam in years.

  • Some of my students did not finish high school or had immigrated to the United States recently, and were still learning English. 

  • One of the best study tools for them was to use Online Practice Tests. Simulated online tests are based on the state exam. 

Recommended Courses


Practice Test Questions

1. Which public agency issues permits for vacuum trucks?

a. California Department of Transportation

b. Department of Building and Safety

c. Regional Water Quality Control Board

d. Department of Public Health

3. How does clay soil affect the surface area of seepage pits?

a. The size of the pits will need to be smaller.

b. Imported soil might be used to install the pits.

c. The pits might need to be connected in series

d. Deeper or more pits might need to be installed


3. Use Contractor License Study Guides

Test questions are great, but relying on them as your only study source is a big mistake. If you are not into reading, you can find C-42 sanitation license exam study books in audio or video format.

Practice test questions for the sanitation license exam do not give you the theory behind what the question is asking you. Use a book or study guide as a reference.



Exam prep books for the sanitation license cover a wide range of topics. They can also be incredibly helpful to refresh your memory on core topics you may have forgotten.

Free contractor license study guides often cover just a snapshot of what you need to know.

Invest in yourself and look for study guides that cover topics such as:


Contractor Exam Topics
  • Installing alternative treatment systems
  • Specialty sanitation systems
  • Removing or repairing existing septic systems
  • Maintaining existing septic systems
  • Planning sanitation systems
  • Estimating sanitation systems
  • Employee training and safety
  • Job site safety

Get the Complete Home Study Kit


4. Contractor Classes

When you see the term “Contractor Classes” you should understand that they are only LAW & BUSINESS classes for construction contractors.

Contractor license schools offer state-specific exam prep classes that cover the basics of construction LAW.

It is essential to understand the distinction between a contractor license and a trade school. The C-42 license test is for journey-level tradesman who has a solid understanding of the sanitation systems trade.

Contractor classes are not meant to teach you your trade.

image of a contractor license looking in frustration down at pieces of paper. blog post teaches sanitation contractors applying for the C-42 license about contractor classes

Taking classes can be very beneficial for those of us who haven’t been in school for a while.

  • Taught by Contractors or construction veterans
  • Live Instruction format with questions and answers
  • Bilingual (depending on the school you chose)
  • In depth classes that cover important exam concepts

Contractor License schools offer several services that can help you get everything taken care of quickly and easily.

Check out this article for a more in-depth look at how to choose the right school!


How to study for the C-42 License Test!

You are trying to get the C-42 sanitation license to make more money, achieve a goal or move up in some way.

It is totally understandable if the idea of taking an exam is intimidating.

  • Remember that most of the people there on test day are in the exact same position as you. 

  • The key is to get some accurate material and be consistent about studying them.

  • Professional athletes, artists, and other top-level tradesmen will all tell you the same thing. Developing mastery is about doing a bunch of little things over and over again

5. Study Consistently!

If you commute, invest in an audio program, you can listen while you drive.

If you are a native Spanish speaker and prefer to watch a recorded class, invest in a bilingual program.

There are a lot of options out there to get you the information you need to know so you can get where you want to be FAST!

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If you have found this article helpful, feel free to check out some of our other free content.

For a complete guide to the C-42 License for Sanitation Contractors see this article!