Welcome to Water Opcert School's FREE downloads page. The following links are provided to assist operators with the certification testing and renewal process. If you have suggestions for other information that could be included on this page, please contact Richard Vierra by email at richard@opcertschool.com. Or, you may call or text the school at (530) 277-2255.

NOTE: Clicking on the links for any of the following downloads will open a new window. When done, close that window to return to this page.

You will need Adobe Reader to view most of the documents linked on this page. To download a free copy of this program click here:

USEPA Ground Water and Drinking Water website:
USEPA Safe Drinking Water Act webpage:
USEPA Drinking Water Quick Reference Guides webpage:

Division of Drinking Water (DDW) website:
To get a copy of California Drinking Water Statutes, 383 pp, Jan 2018: (Please note the disclaimer at the top of each page)
To get a copy of California Drinking Water Regulations, 337 pp, Apr 2018: (Please note the disclaimer at the top of each page)
17-page section of CA Title 22 that details the operator certification process:
8-page section of CA Statutes related to Drinking Water System operator certification:
DDW Treatment & Distribution Operator Certification Unit homepage:

California Water Treatment Plant & Distribution System Operator certification is a three-part process. First, apply to take an exam. Second, after passing the exam, apply for a license. Third, after receiving the license, it must be renewed every three years. Use the following links to access more information about this process:

Water Treatment Operators

~ Treatment Exam Schedule
~ Exam Application form
~ Exam Fee Schedule
~ Exam Step-By-Step Process
~ Exam Minimum Qualifications
~ Exam Expected Range of Knowledge
~ Exam Recommended Reading List
~ Exam Math Conversions & Formulas
~ Prior Water Treatment Exam Results
~ Eligibility Criteria for Certification
~ Certification Fee Schedule
~ Certification Step-By-Step Process
~ Certification Application Form
~ Certification Information Sheet
~ Sample Supervisor Letter
~ License Renewal Form
~ License Renewal Fee Schedule
~ Past Due Renewal FAQs

Water Distribution Operators

~ Distribution Exam Schedule
~ Exam Application form
~ Exam Fee Schedule
~ Exam Step-By-Step Process
~ Exam Minimum Qualifications
~ Exam Expected Range of Knowledge
~ Exam Recommended Reading List
~ Exam Math Conversions & Formulas
~ Prior Distribution Exam Results
~ Eligibility Criteria for Certification
~ Certification Fee Schedule
~ Certification Step-By-Step Process
~ Certification Application Form
~ Sample Supervisor Letter
~ License Renewal Form
~ License Renewal Fee Schedule
~ Past Due Renewal FAQs

Click here for information regarding certification in California for those who currently hold a water operator license issued by another State.

If you hold a California water treatment or distribution operator license and would like information about transferring it to another State, call (916) 449-5611 or (916) 449-5610.

Water Math Reference Materials

Dilution Rectangle Calculations - Used to determine the volume/amount of two different solutions (2 unknowns) that must be combined to produce a certain finished concentration and volume when both initial concentrations are given.

TON Calculations - A brief description of the Threshold Odor Number process used for testing drinking water supplies, with examples of TON & geometric mean computations.

SCADA Signals - How to interpret signals generated by the 4-20mA system standard, with math examples for changing a mA signal into the measurement it represents, and changing a certain measurement into the mA signal that should be generated.