Louisiana Department of Health (LDH) Licensing & Compliance Guide

Louisiana Department of Health – Certified Installer of
Individual Onsite Wastewater Treatment Systems
(IOWTS) Exam Practice Questions with Detailed
Rationales latest 2026 Latest version Q&A |INSTANT
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1. What is the primary purpose of an individual onsite wastewater treatment
system (IOWTS)?
A. To store wastewater permanently
B. To treat and safely disperse wastewater into the environment
C. To transport wastewater to municipal plants
D. To evaporate wastewater
Correct answer: B – IOWTS are designed to treat wastewater and safely disperse
the treated effluent into the soil.


2. Which agency regulates onsite wastewater systems in Louisiana?
A. EPA
B. Louisiana Department of Health (LDH)
C. Department of Environmental Quality
D. Local Fire Marshal
Correct answer: B – LDH is the primary authority regulating onsite wastewater
systems in Louisiana.


3. What component separates solids from liquids in a conventional system?
A. Distribution box
B. Absorption field

,C. Septic tank
D. Soil horizon
Correct answer: C – The septic tank allows solids to settle and scum to float,
separating them from liquid effluent.


4. What material is most commonly used for septic tanks?
A. Plastic only
B. Steel only
C. Concrete, plastic, or fiberglass
D. Wood
Correct answer: C – Approved tanks are commonly made of concrete, plastic, or
fiberglass.


5. What is the minimum function of a septic tank baffle?
A. Speed up flow
B. Prevent solids from exiting the tank
C. Increase oxygen
D. Neutralize bacteria
Correct answer: B – Baffles prevent solids and scum from entering the outlet pipe.


6. Which soil characteristic most affects wastewater absorption?
A. Color
B. Texture and permeability
C. Temperature
D. Organic content only
Correct answer: B – Soil texture and permeability determine how effluent moves
and is treated.

, 7. What does a percolation test measure?
A. Soil compaction
B. Soil absorption rate
C. Water table depth
D. Soil fertility
Correct answer: B – A perc test measures how quickly water moves through soil.


8. When is a percolation test required?
A. After installation
B. During system failure
C. Before system design approval
D. During tank pumping
Correct answer: C – Perc tests are required before system design and approval.


9. What is the purpose of the absorption field?
A. Store wastewater
B. Disinfect wastewater
C. Disperse treated effluent into soil
D. Pump wastewater uphill
Correct answer: C – The absorption field disperses effluent for final treatment in
soil.


10. What condition can cause system failure most rapidly?
A. Proper maintenance
B. Excessive water use
C. Correct soil selection
D. Proper setbacks
Correct answer: B – Excessive water overloads the system and reduces treatment
effectiveness.