REHS Exam Prep Free practice test →

Free REHS Practice Questions

10 free, exam-style Registered Environmental Health Specialist (REHS) practice questions with answers and explanations. No signup required. Work through them below, then take the full free REHS practice test to study every exam domain.

Question 1

An outbreak investigation reveals that 150 wedding guests became ill with vomiting and diarrhea 1-6 hours after eating ham and potato salad prepared by a cook with an infected cut on their hand. The MOST likely causative agent is:

  1. Salmonella enteritidis
  2. Clostridium perfringens
  3. Staphylococcus aureus
  4. Norovirus gastroenteritis
Show answer & explanation

Correct answer: C - Staphylococcus aureus

Question 2

During an inspection, you find that a pot of chili reached 75°F after 2 hours of cooling. The corrective action is to:

  1. Immediately reheat to 165°F and restart cooling or discard
  2. Document the temperature and continue monitoring the cooling process
  3. Transfer the chili to shallow pans and place in refrigerator
  4. Add ice or cold water to accelerate the cooling process
Show answer & explanation

Correct answer: A - Immediately reheat to 165°F and restart cooling or discard

Question 3

Elevated nitrate levels in drinking water are of particular concern because they can cause:

  1. Dental fluorosis in children and adolescents
  2. Methemoglobinemia (blue baby syndrome) in infants
  3. Hepatic dysfunction in elderly populations
  4. Renal calcification in young adults
Show answer & explanation

Correct answer: B - Methemoglobinemia (blue baby syndrome) in infants

Question 4

During a site evaluation for a septic system, an environmental health specialist observes gray mottling at 18 inches below the ground surface. This finding suggests:

  1. The site has excellent drainage and is fully suitable for a conventional septic absorption field
  2. A percolation test is unnecessary because the soil color indicates adequate permeability for effluent
  3. The soil is ideal sandy loam and the septic system can be installed without any design modifications
  4. A seasonal high water table exists at approximately 18 inches and may be too shallow for a conventional system
Show answer & explanation

Correct answer: D - A seasonal high water table exists at approximately 18 inches and may be too shallow for a conventional system

Question 5

A waste solution has a pH of 1.5. This waste exhibits the hazardous characteristic of:

  1. Ignitability
  2. Toxicity
  3. Reactivity
  4. Corrosivity
Show answer & explanation

Correct answer: D - Corrosivity

Question 6

West Nile Virus is primarily transmitted by _____ mosquitoes, with _____ serving as the primary reservoir.

  1. Aedes; humans
  2. Culex; birds
  3. Anopheles; primates
  4. Aedes; rodents
Show answer & explanation

Correct answer: B - Culex; birds

Question 7

If a radiation source produces 100 mR/hr at 2 feet, the intensity at 4 feet would be:

  1. 25 mR/hr
  2. 50 mR/hr
  3. 12.5 mR/hr
  4. 200 mR/hr
Show answer & explanation

Correct answer: A - 25 mR/hr

Question 8

The correct order of the hierarchy of controls from MOST to LEAST effective is:

  1. Administrative → Elimination → Substitution → Engineering → PPE
  2. Elimination → Administrative → Engineering → Substitution → PPE
  3. Elimination → Substitution → Engineering → Administrative → PPE
  4. Substitution → Elimination → Administrative → Engineering → PPE
Show answer & explanation

Correct answer: C - Elimination → Substitution → Engineering → Administrative → PPE

Question 9

During an inspection, you test a public pool and find: pH 8.2, free chlorine 1.5 ppm. The PRIMARY concern is:

  1. The free chlorine level exceeds the maximum allowable concentration for a public swimming pool
  2. The water is too acidic and will cause corrosion of metal components and eye irritation
  3. The pH is above the acceptable range, significantly reducing chlorine effectiveness
  4. No concerns exist because both the pH and free chlorine fall within standard acceptable ranges
Show answer & explanation

Correct answer: C - The pH is above the acceptable range, significantly reducing chlorine effectiveness

Question 10

An environmental health specialist notices a cluster of 15 gastrointestinal illness cases in one week, compared to a typical 2 cases per week. The FIRST step in the investigation should be:

  1. Verify the diagnosis and confirm the existence of an outbreak
  2. Close the suspected restaurant immediately
  3. Begin environmental sampling at all food facilities
  4. Issue a press release warning the public
Show answer & explanation

Correct answer: A - Verify the diagnosis and confirm the existence of an outbreak

Ready for the real thing?

Practice hundreds more REHS questions with instant scoring, weak-area drills, and full exam simulations.

Start the free practice test See pricing