For the operators who keep treated water moving through the pipes, pumps, valves and storage between the plant and the customer.
Start studying D1| Content area | % of the exam | |
|---|---|---|
| Disinfection | 15 | |
| Distribution System Design / Hydraulics | 20 | |
| Equipment Operation / Maintenance / Inspections | 20 | |
| Regulations / Management / Safety | 15 | |
| Water Mains and Piping | 20 | |
| Water Quality / Water Source | 10 |
62% of examinees passed (630 of 1,018) from July 1, 2025 to June 30, 2026. Source: SWRCB Drinking Water Operator Certification Program, Water Distribution Exam Results (through 6/30/2026). The agency updates these tables every six months.
Hydraulics: static pressure · an original practice item written only from publicly available sources, not a real exam question
The water level in a storage tank is 115 ft above a hydrant. With no flow in the system, what is the static pressure at the hydrant?
A. 49.8 psi
Each foot of water exerts 0.433 psi, so 115 ft × 0.433 = 49.8 psi. 266 multiplies by 2.31, which converts psi to feet, not feet to psi; 115 treats feet and psi as the same unit; 7,180 multiplies by 62.4 lb/ft³, which gives pounds per square foot, and never divides by 144 to reach pounds per square inch.
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Topic coverage follows Expected Range of Knowledge for Drinking Water Distribution 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.