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Coagulation and sedimentation basins at a drinking-water treatment plant

New York · Water Treatment · IIIA

New York Grade 3 Water Treatment Operator Exam

The New York Grade 3 water treatment certification is designated IIIA and issued by NYS Department of Health (drinking water); NYS Department of Environmental Conservation (wastewater). Advanced certification for shift leads and operators at larger systems with complex processes.

Photo: U.S. EPA (public domain)

Applied math is a significant part of the New York IIIA exam.

Practicing calculations like dosage, detention time, and loading before test day is one of the most effective ways to prepare, alongside reviewing your state’s official exam content outline.

Exam facts

Exam facts
Grade levelIIIA
Questions120
Time limit180 minutes
Passing score70%
DifficultyAdvanced
Exam administered byNYS DOH / DEC (in-house exams)

Prerequisites for IIIA

  • Grade 2 certification
  • 3–4 years of operating experience
  • Some post-secondary coursework (varies by state)

Confirm exact requirements with NYS Department of Health (drinking water); NYS Department of Environmental Conservation (wastewater).

What's on the exam

  • Coagulation and flocculation
  • Sedimentation and clarification
  • Filtration (conventional, direct, membrane)
  • Disinfection and disinfection byproducts
  • Corrosion control and stabilization
  • Source water and watershed protection
  • Advanced process optimization
  • Regulatory compliance strategy

The math on the Water Treatment exam

These calculations are commonly included in water treatment operator exam preparation and may appear on your exam depending on your certification level and state. Practicing them is one of the most effective ways to prepare.

  • Chemical dosage (mg/L to lbs/day)
  • Chlorine demand and CT calculations
  • Detention time
  • Filter loading and backwash rate
  • Flow rate and velocity
  • Percent strength of solutions

Free IIIA practice questions

Sample questions with full explanations at this level.

Take the practice quiz →

Frequently asked questions

What is the New York Grade 3 water treatment certification called?
In New York, the Grade 3 water treatment certification is designated IIIA, issued by NYS Department of Health (drinking water); NYS Department of Environmental Conservation (wastewater).
How many questions are on the exam and what score do I need?
The exam has about 120 questions with a 180-minute time limit, and you need 70% to pass. It is administered by NYS DOH / DEC (in-house exams).
What are the prerequisites for IIIA in New York?
Typical prerequisites: Grade 2 certification; 3–4 years of operating experience; Some post-secondary coursework (varies by state). Exact requirements are set by NYS Department of Health (drinking water); NYS Department of Environmental Conservation (wastewater).