California wastewater practice test
Practice questions for the Grade I and II wastewater operator exams, written from the State Water Board exam information and explained one by one. Train by topic, then take a timed mock exam.
- All 234 questions and answers
- Free practice test
- Money-back guarantee
Take the practice test
10 practice questions from the question catalog. How many can you get right?
How the California wastewater operator exam works
Wastewater treatment plant operators in California need a certificate from the State Water Resources Control Board. The exam is taken on a computer at a Prometric test center.
The Grade I exam has 80 items in 150 minutes (true or false, multiple choice and math). You need 70 percent of the points and a minimum score on the math part. Topics include preliminary, primary and secondary treatment, ponds, sludge, disinfection, safety and regulations.
This site is an independent exam trainer. The certificate itself is issued by the State Water Board, not by us. Our questions are written from the official exam information.
The topics of the test
The 234 questions in the catalog are spread across these areas. In the trainer you practice all of them until every area sticks.
- Safety and Hazards26 questions
- Sampling, Laboratory Analysis and Wastewater Characteristics30 questions
- Preliminary and Primary Treatment23 questions
- Secondary Treatment (Activated Sludge, Trickling Filters, RBC)31 questions
- Stabilization Ponds16 questions
- Sludge Digestion and Solids Handling23 questions
- Disinfection and Dechlorination20 questions
- Regulations, Classification and Operator Certification29 questions
- Process Math and Unit Conversions36 questions
How many questions can you get right?
10 practice questions, free and without signing up. At the end you see whether it would already be enough for the test.
How you learn with us
No rote memorizing from start to finish. The trainer remembers what you know and practices exactly the rest with you.
Take the practice test
10 practice questions, free. Afterwards you know where you stand.
All questions with solutions
The complete catalog with 234 questions, each with the correct answer.
Tests that adapt to you
Every round puts the questions together anew. Whatever you got wrong comes back until it sticks.
Pass or get your money back
If you fail despite practicing, you get your last payment back.
All questions and answers in the online trainer
Everything you need for the knowledge test in one place. No book, no class, on your phone or computer.
- 234 questionsAll with solutions
- 80 in 150 minutesLike in the real test
- 9 topic areasPractice targeted, one by one
- 100 %Money-back guarantee
The complete question catalog
All 234 questions that could come up, each with the correct answer. You learn exactly what gets asked.
For every question you see how often others get it wrong and which answer they mix it up with. That way you spot the traps.
Test simulation like the real thing
80 questions, 150 minutes, graded like the real test: at least 56 correct answers out of 80 (70 percent).
Every round is shuffled anew. Afterwards you see right away whether you would have passed and what is still missing.
Practice that adapts to you
The trainer remembers what you already know. Wrong answers come back until they stick, and a question only counts as learned once you have answered it correctly several times with time in between.
You can also practice individual topics or just your weak spots.
Your plan until the test
Enter your test date and the trainer spreads the questions across the remaining days. That way a small round waits for you every day instead of cramming everything the last evening.
Your progress shows you at any time when you are ready for the test.
Short videos to swipe
Learn like on Instagram or TikTok: Every question comes as a short video, you tap your answer and swipe to the next one. Whatever you got wrong shows up more often.
Ideal for in between, on the train or on a break.
Pricing
Both options include all questions and answers and all trainer features. You only decide whether you pay weekly or once.
Weekly pass
$7.99per week
- All 234 questions and answers
- All trainer features
- Cancel anytime
Permanent access
$39.99one-time
- All 234 questions and answers
- All trainer features
- Pay once, no subscription
Our money-back guarantee applies to the subscription.
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Our money-back guarantee
We are confident that you will pass with the trainer. If not, we refund the last payment of your subscription. The guarantee applies to the subscription, not to lifetime access.
It is that simple: Within 30 days after the test, send us a short email at [email protected] with proof, for example a photo of your test result. No follow-up questions, no form. The exact conditions are in the terms and conditions.
Frequently asked questions
How is the Grade I exam scored?
The Grade I exam has 80 items worth 135 points. You need 70 percent of the points and at least 20 points on the math problems. Grade II has 90 items and the same 70 percent rule.
What do I need for Grade II?
Grade II requires experience as a Grade I operator in addition to the education points. Check the State Water Board pages for the current requirements.
Are these the real exam questions?
No. The State Water Board does not publish its exam questions. All questions here are our own, written from the official exam information. Our mock exam uses multiple choice only.
Do I get my certificate here?
No. This site only helps you prepare. Certificates are issued by the State Water Resources Control Board after you pass the exam.