WT-EL 100 Series

About the Assessment

The WT-EL 100 Series is IPMA-HR’s most recently developed entry-level wastewater operator-in-training (OIT) assessment and uses the most modern development approach that relies on a combination of (3) legally and professionally supported sources of validity evidence.  

Assessment Features




100 Items

Time Limit

2 Hours and 30 minutes



Content Areas

Ability to Learn and Apply Information

Mathematical and Logical Reasoning

  • Understand and apply basic mathematical data and rules
  • Examples of mathematical concepts assessed include volume, conversions, solution strength and flow rate

Reading Comprehension

  • Reading passages based on wastewater topics
  • CLOZE (Fill-in-the-blank) items

Basic Chemistry

  • High school-level chemistry concepts such as organic and inorganic compounds, acids and bases, metals and nonmetals, states of matter, and aerobic and anaerobic organisms

Mechanical Aptitude

  • Interpreting gauges, dials, and other indicators
  • Understanding mechanical concepts and principles 

Safety Sense

  • Understanding general safety and health hazards inherent in a wastewater treatment plant
  • Applying best safety practices and procedures  

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Orders are fulfilled exclusively for authorized IPMA-HR test users. Contact us to become an authorized IPMA-HR test user.

Technical Report

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Study Guide

A study guide with full 100-question practice test and twenty-five answer explanations is available for purchase. We recommend agencies secure access to the study guide for all candidates to ensure that financial burdens do not result in unequal access to study materials.