Exam catalog
Question banks
Water Treatment Operator — Class I Available
326 original questions matched to the 2025 Need-to-Know Criteria blueprint: Treatment Process (101), Equipment Operation & Maintenance (85), Laboratory Analysis (52), Source Water Characteristics (49), and Security, Safety & Administrative Procedures (39). Includes 31 calculation items with worked solutions, practice sets by content area, and a full 110-question timed mock exam.
Wastewater Treatment Operator — Class I Available
326 original questions matched to the 2025 Need-to-Know Criteria blueprint: Equipment Evaluation, Maintenance & Operation (127), Treatment Process Evaluation & Adjustment (124), Laboratory Analysis (33), and Security, Safety & Administrative Procedures (42). Includes 33 calculation items with worked solutions, practice sets by content area, and a full 110-question timed mock exam.
Water Treatment Operator — Class II In development
The next step up from Class I, covering the Class II Need-to-Know Criteria with the same verification process.
All-access ($99) includes this bank the day it launches.
Water Distribution Operator — Class I Available
326 original questions matched to the 2025 Need-to-Know Criteria blueprint: Distribution System Components (114), Equipment Installation, Operation, Maintenance & Repair (98), Water Quality Monitoring, Evaluation & Laboratory Analysis (49), and Security, Safety, Administrative Procedures & Public Interactions (65). Includes 30 calculation items with worked solutions, practice sets by content area, and a full 110-question timed mock exam.
Water Treatment Class I bank contents
| Content area (2025 Need-to-Know Criteria) | Questions in the bank |
|---|---|
| Treatment Process | 101 |
| Equipment Operation and Maintenance | 85 |
| Laboratory Analysis | 52 |
| Source Water Characteristics | 49 |
| Security, Safety, and Administrative Procedures | 39 |
| Total | 326 |
Includes 31 calculation items with worked solutions. Bank contents and prices verified October 24, 2026.
Wastewater Treatment Class I bank contents
| Content area (2025 Need-to-Know Criteria) | Questions in the bank |
|---|---|
| Equipment Evaluation, Maintenance, and/or Operation | 127 |
| Treatment Process Evaluation and Adjustment | 124 |
| Laboratory Analysis | 33 |
| Security, Safety, and Administrative Procedures | 42 |
| Total | 326 |
Includes 33 calculation items with worked solutions. Bank contents verified October 25, 2026.
Water Distribution Class I bank contents
| Content area (2025 Need-to-Know Criteria) | Questions in the bank |
|---|---|
| Distribution System Components | 114 |
| Equipment Installation, Operation, Maintenance, and Repair | 98 |
| Water Quality Monitoring, Evaluation, Adjustment, and Laboratory Analysis/Interpretation | 49 |
| Security, Safety, Administrative Procedures, and Public Interactions | 65 |
| Total | 326 |
Includes 30 calculation items with worked solutions. Bank contents verified October 25, 2026.
How each bank is built
Source-cited, independently verified, kept current
1. Written from the sources
Questions are authored against WPI's published Need-to-Know Criteria and its approved reference list (Sacramento State OWP texts, AWWA/WEF guides, EPA regulations). Every question carries its citation, shown to you with the answer.
2. Checked by a second pass
An independent reviewer re-derives every answer without seeing the key — and recomputes every calculation step by step. Disagreement means the question is cut or rewritten, never argued in. Class I passed at 326 of 326, zero disputed items.
3. Re-verified on a schedule
Each bank gets a full re-verification pass every year, plus an immediate pass whenever WPI republishes its criteria or the EPA changes a rule a bank cites. Buyers can report an error on any question, in one click.
Straight answers
What TradeQBank is — and is not
- Original questions only. The real exam is confidential. Anyone selling “actual exam questions” is selling recalled material; we don't touch it.
- No pass guarantee. We give you verified, blueprint-matched practice and honest score feedback by content area. Your result depends on your preparation.
- Not affiliated with WPI or ABC. TradeQBank is an independent study product. We reference the Need-to-Know Criteria only to describe what the material covers.
- Wrong-answer refund. Find a verifiably wrong answer in a bank you bought — verified means we confirm it against the cited source — and we fix it and refund that purchase.
Pricing
Simple, one-time pricing
Single exam bank
One full bank: all questions, practice by content area, timed mock exams, worked explanations, and free updates whenever the bank is re-verified.
All-access
Every bank we publish — current and future — for one price. Built for operators climbing the class ladder.
Stay in the loop
New banks are in development
Water Treatment Class II is being built to the same verified standard. Join the email list to hear when it launches — plus occasional study tips drawn from the banks. No spam, unsubscribe anytime.
FAQ
Common questions
How many questions are on the WPI Water Treatment Operator Class I exam, and what score passes?
The exam has 110 questions: 100 scored questions plus 10 unscored pretest questions being evaluated for future exams. You need 70% or higher on the scored questions to pass. Our mock exam mirrors this format — 110 questions drawn in blueprint proportions, scored against the same 70% mark.
What topics does the Class I exam cover?
Five content areas from the WPI 2025 Need-to-Know Criteria: Treatment Process, Equipment Operation and Maintenance, Laboratory Analysis, Source Water Characteristics, and Security, Safety, and Administrative Procedures. Roughly 10% of the exam is calculation items, worked with the standard formula and conversion table candidates are given during the exam — our banks practice those formulas directly.
Are these the actual exam questions?
No. The real exam is confidential and its questions are never released. Every TradeQBank question is original, written to the same published blueprint and derived from the exam's approved references, so the material, difficulty, and formats match what the exam covers.
How do you know your answers are right?
Each answer is traceable to a cited authoritative source, then an independent second reviewer re-derives the answer without seeing the key. Only full agreement ships. Every calculation is recomputed step by step. See Our Method for the details, and note the wrong-answer refund on Pricing.
Will this guarantee I pass?
No product honestly can. What we can do is show you exactly which content areas you're weak in — the sample and the mock exam both break your score down by area — with verified questions that match the real blueprint.
Some states run their own exam variants. Does this still help?
Most states use the standardized WPI exams. A few large states layer state-specific variants on top. This bank targets the standardized Class I exam; state-variant banks, clearly labeled, are on the roadmap.
How much does TradeQBank cost?
Each exam bank is $49 one-time. All-access is $99 one-time and covers every current and future bank. A 25-question sample of each bank is free with no account.