T5 is the one drinking water grade examined orally: a 30-minute panel exam with 6 questions, not a written multiple-choice test.
California's certificate for running a drinking water treatment plant.
Start studying T534% of examinees passed (30 of 89) from July 1, 2025 to June 30, 2026. Source: SWRCB Drinking Water Operator Certification Program, Water Treatment Exam Results (through 6/30/2026). The agency updates these tables every six months.
Oral panel practice: operational response · an original practice item written only from publicly available sources, not a real exam question
Practice prompt for the oral panel: during a storm, the effluent turbidity on one filter climbs past your plant's action level while the combined filter effluent is still within its limit. Walk the panel through what you do and why.
A strong answer is structured, not a list of guesses. First protect the finished water: take the filter out of service or send it to waste, and confirm the combined effluent and clearwell stay in compliance. Then diagnose: check raw water turbidity and the coagulant dose (a jar test at the new raw water quality), the filter's run time and head loss, and any recent backwash or rate change. Bring the filter back only after a proper backwash and a filter-to-waste period shows it has ripened. Individual filters carry their own turbidity monitoring and follow-up triggers, not just the combined effluent, so check which apply to this event. Finally, document it, make any report your operating permit and the Title 22 turbidity rules require to the Division of Drinking Water district office, and say how you would prevent a repeat. The panel is listening for priorities and judgement as much as for the right steps.
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Topic coverage follows Expected Range of Knowledge for Drinking Water Treatment Exam (SWRCB Division of Drinking Water, rev. 4/2020). Practice questions are written only from publicly available sources (that outline and the regulations and references it cites); they are not real exam questions, which are confidential. Check current application requirements, fees and exam dates on the certifying body's own page: official certification page.
Questions, flashcards, and explanations are AI-written from publicly available sources only: the exam content outlines and candidate materials each certifying body publishes without restriction, and the regulations and technical references they cite. No confidential material is used, including actual exam questions, recollections of any exam sat by the author, or any handbook or document released under a confidentiality agreement. Content is then put through repeated review — regulatory values checked against primary sources, every calculation recomputed, and errors corrected — plus spot checks by the author, who holds California water operator certifications and a California civil engineering licence. Those spot checks are sampling, not a professional review: nothing here is stamped, sealed, or offered as engineering advice, and not every item has been individually verified, so mistakes can still slip through.