FE discipline · specifications of July 2020 · checked Oct 29, 2026
FE Environmental exam, water, air and waste
The FE Environmental exam is the Fundamentals of Engineering test for environmental engineers: 110 questions in 5 h 20 min, sat at a Pearson VUE site and written to specifications in force since July 2020. Four water areas alone carry 41 to 62 of those questions.
Engineer intern (EI) or engineer-in-training (EIT) certification from a state boardNCEES writes and scores the exam; the state licensing board issues the EI/EIT certificate.
NCEES: FE exam · NCEES Examinee Guide, May 2026 (PDF) [1][2]
Questions
110 questionsIncludes unscored pretest questions that are not marked.
NCEES: FE exam · NCEES Examinee Guide, May 2026 (PDF) [1][2]
Question types
Multiple choice plus alternative item types (multiple correct, point and click, drag and drop, fill in the blank)No partial credit on alternative items.
NCEES: FE exam · NCEES Examinee Guide, May 2026 (PDF) [1][2]
Appointment
6 hoursNondisclosure agreement 2 min, tutorial 8 min, exam 5 h 20 min, scheduled break 25 min (the guide table sums it as 5 h 55 min).
NCEES: FE exam · NCEES Examinee Guide, May 2026 (PDF) [1][2]
Delivery
Computer-based at Pearson VUE test centersNo online or at-home option.
NCEES: FE exam · NCEES Examinee Guide, May 2026 (PDF) [1][2]
When you can test
Year-roundNCEES testing windows run Jan–Mar, Apr–Jun, Jul–Sep and Oct–Dec.
NCEES: FE exam · NCEES Examinee Guide, May 2026 (PDF) [1][2]
Units
SI and USCS
NCEES: FE Environmental specifications, July 2020 (PDF) [3]
Reference supplied
FE Reference Handbook, on screen as a searchable PDFThe current version is free in your MyNCEES account; on exam day search with the box on the left (Ctrl+F does not work); no personal copies.
NCEES Examinee Guide, May 2026 (PDF) · NCEES: FE exam [1][2]
Calculator
Any Casio fx-115 or fx-991 model, the HP 33s or HP 35s, or any TI-30X or TI-36X model; one in the room, plus an on-screen TI-30XSThe list is reviewed every year; spares stay in your locker.
Not published (a scaled score against a minimum ability level)The number of correct answers is converted to a scaled score; wrong answers cost nothing; first-time and repeat takers are graded to the same standard.
July 2020 editionNo FE change appears in the NCEES notice of July 20, 2026, which lists exam changes through fall 2027; NCEES gives boards at least one year of notice.
NCEES: FE Environmental specifications, July 2020 (PDF) · NCEES memo to member boards, July 20, 2026: changes through fall 2027 (PDF, Virginia board copy) [3][7]
15 knowledge areas, by number of questions
Each of the 15 areas comes with a question range in the specification, not a percent share. The ranges add up to 100–154 because each one is a band, while any single exam form has 110. Fluid mechanics and hydraulics and water and wastewater are the two largest areas at 12–18 questions each.
Shared with the other FE disciplines: mathematics (5–8), probability and statistics (4–6) and ethics (5–8) are on the FE practice test page; engineering economics (5–8) has its own page.
Thermodynamics (3–5): cycles and gas laws are covered under FE Mechanical thermodynamics; heating values and combustion stay on the air page.
Environmental law is tested under Ethics
The ethics area here includes compliance with codes, standards and regulations, and the specification names seven statutes as examples: CWA, CAA, RCRA, CERCLA, SDWA, NEPA and OSHA. The statute basics sit next to the engineering: water law, air law, waste law.
4 sample problems with worked solutions
0 / 4 answered · 0 correct
Question 1 of 4 · Environmental Chemistry · 7–11 items
A chlorinated solvent plume has migrated into a deep, anaerobic groundwater aquifer with low redox potential and available organic substrate. Which transformation mechanism is most likely to dominate the removal of highly chlorinated ethenes in this environment?
Solution
Low redox potential plus organic substrate means anaerobic conditions: highly chlorinated ethenes act as electron acceptors and undergo sequential reductive dechlorination (PCE → TCE → DCE → VC → ethene).
Hydrolysis of chlorinated ethenes is extremely slow, with half-lives of years to centuries, so it cannot dominate.
Dehydrohalogenation removes HX from chlorinated ethanes, not ethenes, and an oxidative pathway is unlikely at low redox potential.
Photolysis needs sunlight, which does not reach a deep aquifer.
In a reducing aquifer with an electron donor, PCE and TCE serve as electron acceptors and lose chlorine atoms one by one, which is the dominant fate of highly chlorinated ethenes.
Aerobic oxidation requires dissolved oxygen, and highly chlorinated ethenes such as PCE resist oxidation even when oxygen is present.
Question 2 of 4 · Fluid Mechanics and Hydraulics · 12–18 items
In a laminar flow regime (Re<2000), the average velocity of a fluid in a pipe is doubled. How does the head loss due to friction change?
Solution
Laminar flow: f = 64/Re, so the Hagen–Poiseuille form of Darcy–Weisbach is linear in velocity (Fluid mechanics: pipe flow).
hf = (64/Re)(L/D)(V2/2g) = 32μLV/(ρgD2) ∝ V
Head loss cannot fall when the velocity rises; halving would mean an inverse dependence on V.
Laminar f = 64/Re does fall as V rises, but only by half while V² quadruples, so the head loss still grows.
With f = 64/Re, Darcy–Weisbach becomes hf = 32μLV/(ρgD2), which is linear in V, so doubling V doubles hf.
A factor of 4 assumes a constant friction factor (hf ∝ V2), which holds for fully rough turbulent flow, not laminar.
A factor of 8 would need hf ∝ V3, which no pipe-flow regime follows.
Question 3 of 4 · Surface Water Resources and Hydrology · 9–14 items
A 20-acre watershed has a Curve Number (CN) of 85. During a storm event with 4.0 inches of precipitation, what is the total volume of direct runoff generated?
Given
Watershed area = 20 acres
Curve number CN = 85
Precipitation P = 4.0 in
Find
Direct runoff volume (ac-ft)
Solution
SCS (NRCS) curve number runoff, then depth × area (Hydrology: NRCS curve number).
S = 1000/CN − 10 = 1.76 in; Ia = 0.2S = 0.35 in
Q = (P − Ia)2/(P − Ia + S) = (3.65)2/5.41 = 2.46 in
V = 2.46 in × (1 ft/12 in) × 20 ac = 4.1 ac-ft
2.5 is the runoff depth in inches (2.46 in), not a volume; it still has to be spread over 20 acres and converted to feet.
S = 1000/85 − 10 = 1.76 in, Q = (4.0 − 0.35)2/(4.0 − 0.35 + 1.76) = 2.46 in, and 2.46 in ÷ 12 × 20 ac = 4.1 ac-ft.
4.6 ac-ft drops the initial abstraction (Q = P2/(P + S) = 2.78 in), which overstates runoff.
6.7 ac-ft treats all 4.0 in of rain as runoff, ignoring the retention the curve number represents.
49 is the volume in acre-inches (2.46 in × 20 ac); dividing by 12 gives acre-feet.
Question 4 of 4 · Environmental Chemistry · 7–11 items
Trichloroethylene (TCE) is present in water at a concentration of 0.050 mg L−1. The Henry's Law constant for TCE is 0.0090 atm · m3/mol at 25°C. What is the equilibrium concentration of TCE in the air phase in mg/m3?
Given
TCE aqueous concentration = 0.050 mg/L
Henry's law constant H = 0.0090 atm·m3/mol
Temperature = 25 °C
Find
Equilibrium TCE air concentration (mg/m3)
Solution
Convert the Henry's constant to dimensionless form, then apply it to the water concentration (Environmental chemistry: Henry's law).
136 mg/m3 divides 0.050 mg/L by 0.368, which inverts the air–water ratio Cair/Cwater.
Answer every question to see your score
From this exam to a PE license
Passing leads to EI/EIT certification. The PE exam named for this field: PE Environmental (PE exam). The steps and the board rules: EIT certification and how to become a PE.
Degree
EAC/ABET bachelor’s degree in engineering (the Model Law also counts ETAC/ABET, master’s and doctoral routes, with different experience years).
What changed:Outline unchanged since the July 2020 edition; the exam fee rose from $175 to $225 on January 1, 2024. A guide that still quotes $175 was written before 2024. One that cites a numbered handbook edition may describe an older copy; the edition on screen is the current one, free in MyNCEES.
Which areas carry the most FE Environmental questions?
Of the fifteen areas, the largest are fluid mechanics and hydraulics and water and wastewater (12–18 questions each), then surface water and hydrology (9–14). Four areas are shared with the other FE disciplines: mathematics, statistics, ethics and engineering economics.
Is there a remote or at-home sitting?
No. You sit it at a Pearson VUE center, any week of the year; there is no version you can take from home.
What calculator goes into the exam room?
One of your own from the approved Casio, HP and TI families, and nothing else: FE exam calculators.
Worked environmental problems, on your phone
FE Environmental questions, answers and worked solutions in a study app.