What do FE Environmental practice problems actually look like?

Mostly multiple choice with four options, usually phrased 'most nearly'. The options sit close enough that you cannot eliminate them by inspection, and on this exam several differ only in how one unit was converted. NCEES gives 110 questions in a 6-hour appointment, of which 5 hours 20 minutes is exam time, so the working time per question is under three minutes once you account for reading, a handbook lookup and a check. NCEES also uses alternative item types (multiple correct answers, point-and-click, drag-and-drop and fill-in-the-blank), each scored right or wrong with no partial credit.

Is the FE Environmental exam mostly water?

Not quite, but water is the biggest block. Four of the fifteen knowledge areas have water as their subject (Fluid Mechanics and Hydraulics, Water and Wastewater, Surface Water Resources and Hydrology, and Groundwater, Soils, and Sediments), and together they carry 41 to 51 of the 110 questions, 37 to 46 percent of the exam. Their ranges add to 62, but the fifteen area minimums already add to 100, so only 10 questions on any exam sit above them. Fluid Mechanics and Water and Wastewater are tied as the two largest blocks on the exam. Air Quality gets 8 to 12 and Solid and Hazardous Waste 7 to 11, which is fewer than most candidates assume. The grouping into 'water areas' is ours; the question ranges are NCEES's.

How many questions are on each FE Environmental topic?

The specification allocates 12-18 each to Fluid Mechanics and Hydraulics and to Water and Wastewater; 9-14 to Surface Water Resources and Hydrology; 8-12 each to Groundwater, Soils and Sediments and to Air Quality and Control; 7-11 each to Fundamental Principles, Environmental Chemistry, and Solid and Hazardous Waste; 5-8 each to Mathematics, Ethics and Professional Practice, and Engineering Economics; 4-6 each to Probability and Statistics, Health Hazards and Risk Assessment, and Energy and Environment; and 3-5 to Thermodynamics. The ranges sum to between 100 and 154 across the 15 areas against an exam of 110, so no single exam hits every maximum.

Am I looking at the right FE Environmental specification?

Check the date on it. NCEES still hosts an obsolete January 2014 specification alongside the current one, and it is easy to land on by searching. The blueprint in force is the one headed 'Effective Beginning with the July 2020 Examinations', and as of mid-2026 no revision to it has been announced. If the document you are studying from does not say July 2020, find the one that does.

What reference material do you get on the FE Environmental exam?

The exam is closed book with an electronic reference: the NCEES FE Reference Handbook is supplied on-screen as a searchable PDF, and you cannot bring your own copy or any outside material. Two habits pay off. Practice with the searchable PDF rather than a printed copy, because finding an equation is a timed skill. And check what the handbook actually contains for your weaker topics: its coverage is uneven, and some subjects the specification examines are thinner in the handbook than you would expect.

FE Environmental practice problems: it is a water exam

Ask an engineer what FE Environmental covers and you will hear about air pollution, waste and sustainability. Those three areas together are 19 to 29 questions, at most about a quarter of the exam. Four water areas are up to 46% of it. Here are three practice problems from the parts that actually dominate, and a pattern in the wrong answers that is worth more than any of the three.

Updated October 6, 2026 · by the FE → PE Prep team

110

Questions

5h 20m

Exam time

Knowledge areas

37–46%

Water areas

The pattern in the wrong answers

Read the three solutions below and one thing repeats. On this exam few points are lost because someone could not remember an equation. The handbook prints most of the equations you need, though not every conversion or basic formula, and the exam gives you the handbook. The points are lost on what gets fed into them.

The distractors are substitution errors, not formula errors: a coefficient left out, an inverted ratio, a unit conversion done halfway, a head read from the wrong elevation. Each produces a complete, believable number that no amount of re-reading the formula will catch.
Some wrong answers pass a units check. In the Darcy problem, a head drop taken from the ground-surface elevations is still in meters, and a flow area taken along the flow path is still in square meters. Only reading the field data correctly gives them away.
Units are a favorite trap. The handbook prints the rational method only in U.S. units, so on an SI problem the conversion is yours, and two of the three wrong options in that problem are conversions done halfway. Checking the units is worth more here than a second pass through the algebra.
The clock is tighter than the appointment. Six hours sounds generous, but only 5 hours 20 minutes is exam time. The rest is a nondisclosure agreement, a tutorial and a scheduled break. Across 110 questions that is under three minutes each, covering the read, the lookup and the check.

Three practice problems

One each from surface water, hydraulics and groundwater, three of the four water areas. These are drawn from our free FE Environmental set. Try each one before you open the solution, and when you do, read the distractor notes rather than just the answer.

1. Peak runoff by the rational method

The rational method is the handbook's formula for peak discharge, but the handbook prints it only in U.S. units (Q = CIA, with Q in cfs, I in in./hr and A in acres). This problem is in SI and does not hand you a conversion factor. Q = CiA still holds in any consistent units, with i in m/s and A in m², which comes to Q = CiA/360 with i in mm/h and A in hectares.

1
easy
A. Runoff & water budget
An urban catchment of 12 ha has a runoff coefficient of 0.70. The design rainfall intensity, for a storm lasting the catchment's time of concentration, is 90 mm/h. The peak runoff rate is most nearly:
Figure — drag or pinch to move around
1. 0.756 m³/s
2. 0.843 m³/s
3. 2.10 m³/s
4. 3.00 m³/s
Show the answer & worked solution
Answer: C.2.10 m³/s
The handbook's Rational Formula $Q = CIA$ works in any consistent units. With $i = 90\text{ mm/h} = \dfrac{90/1000\text{ m}}{3600\text{ s}} = 2.50\times10^{-5}$ m/s and $A = 12\text{ ha} = 120{,}000$ m², $Q = (0.70)(2.50\times10^{-5})(120{,}000) = 2.10$ m³/s. (The same thing in one step: $Q = CiA/360$ with $i$ in mm/h and $A$ in ha.) Distractors: the runoff coefficient $C$ left out (treated as 1); only the millimeters converted to meters ( $CiA/1000$ ), with the hectares and the hours left unconverted; and the handbook's U.S. form used with $i = 90/25.4 = 3.54$ in./hr but the 12 ha entered as if they were acres (1 ha = 2.47 acres), then the cfs converted to m³/s.

What the distractors teach

The answer is 0.70 × (2.5 × 10⁻⁵ m/s) × 120,000 m² = 2.10 m³/s. Convert only the millimeters to meters, CiA/1000, and skip the hectare and hour conversions, and you get 0.756. Switch to the handbook's U.S. form, convert 90 mm/h to 3.54 in./hr but enter the 12 ha as 12 acres, and the cfs you convert back comes to 0.843. Leave C out altogether, as if every drop ran off, and you get 3.00. Nobody here has forgotten the equation. Two lost a unit conversion and one dropped the coefficient, and a runoff figure that is wrong by a factor of two or three still looks like a runoff figure.

2. Velocity through a pipe contraction

Fluid Mechanics and Hydraulics is tied for the largest block on this exam, and continuity is its most basic statement. There is one idea being tested and it is not the equation.

2
medium
A. Fluid statics & dynamics
Water flows steadily through a pipe that contracts from a diameter $D_1 = 200$ mm to $D_2 = 150$ mm. The upstream velocity is $V_1 = 1.5$ m/s. The velocity in the smaller section is most nearly:
Figure — drag or pinch to move around
1. 0.844 m/s
2. 2 m/s
3. 2.67 m/s
4. 4.74 m/s
Show the answer & worked solution
Answer: C.2.67 m/s
Continuity (FE Reference Handbook 10.6 p. 185): the same flow $Q=Av$ passes both sections, so $A_1V_1=A_2V_2$ . With $A=\pi D^2/4$ the $\pi/4$ cancels, leaving $V_2=V_1\left(\dfrac{D_1}{D_2}\right)^2=1.5\left(\dfrac{200}{150}\right)^2=2.67$ m/s, faster in the smaller section, as it must be. Distractors: the diameter ratio used un-squared, $V_1D_1/D_2$ (2 m/s), forgetting that area goes as $D^2$ ; the area ratio inverted, $V_1(D_2/D_1)^2$ (0.844 m/s), which would have the water slow down in the smaller section; and the ratio squared twice, $V_1(D_1/D_2)^4$ (4.74 m/s), the area-ratio squaring applied a second time.

What the distractors teach

Area goes as the square of diameter, and every wrong answer is a different way of mishandling that one fact. Use the diameter ratio without squaring it and you get 2 m/s. Square it twice and you get 4.74 m/s. Invert the area ratio and you get 0.844 m/s, a contraction that slows the water down, which a physical sanity check rules out before you touch the arithmetic. The right answer is 1.5 × (200/150)² = 2.67 m/s.

3. Aquifer discharge by Darcy's law

Darcy's law is three symbols long and the handbook prints it. This problem is here because two of its inputs come from field data you have to read correctly, the hydraulic gradient from two wells and the flow area from the aquifer's shape, and every distractor reads one of them wrong.

3
easy
A. Darcy's law & hydrogeology
Two monitoring wells 600 m apart along the direction of flow are screened in a confined sand aquifer 12 m thick. The upgradient well has a ground-surface elevation of 131.0 m and a water-level elevation of 124.6 m; the downgradient well, 127.1 m and 122.2 m. The aquifer's hydraulic conductivity is 15 m/d and its effective porosity is 0.30. The discharge through a 400-m-wide section of the aquifer, perpendicular to the flow, is most nearly:
1. 86.4 m³/d
2. 288 m³/d
3. 432 m³/d
4. 468 m³/d
Show the answer & worked solution
Answer: B.288 m³/d
The head in each well is its water-level elevation, so $\Delta h = 124.6 - 122.2 = 2.4$ m and $i = \Delta h/L = 2.4/600 = 0.004$ . The flow area is the aquifer section normal to the flow, $A = b\,w = 12\times400 = 4{,}800$ m². Darcy's law (handbook, Civil Engineering — Darcy's Law): $Q = K\,i\,A = 15\times0.004\times4{,}800 = 288$ m³/d. Porosity does not enter the discharge; it only turns the Darcy velocity into the seepage velocity. Distractors: the flow area reduced to the pore area $nA$ (porosity belongs in the seepage velocity, not in the discharge); the ground-surface elevations used for the head drop ( $131.0-127.1 = 3.9$ m) instead of the water levels; and the area taken along the flow path, $b\,L = 12\times600$ m², instead of normal to it.

What the distractors teach

Take the head drop from the ground-surface elevations (131.0 − 127.1 = 3.9 m) instead of the water levels (124.6 − 122.2 = 2.4 m) and you get 468. Take the area along the flow path, 12 × 600 m², instead of across it, 12 × 400 m², and you get 432. Shrink the area to the pores, 0.30 × 4,800 m², and you get 86.4. The answer is 15 × (2.4/600) × 4,800 = 288 m³/d. Head is the water-level elevation, the area is the one the water crosses, and porosity belongs to the seepage velocity, not to the discharge.

Where the 110 questions come from

NCEES publishes how many questions come from each of the fifteen knowledge areas. The four marked below have water as their subject. The grouping and the arithmetic are ours and the ranges are NCEES's: together those four carry 41 to 51 of the 110 questions.

FE Environmental knowledge areas and question counts, per the NCEES specification effective July 2020
Knowledge area	Questions
MathematicsAnalytic geometry, calculus, differential equations, numerical methods.	5–8
Probability and StatisticsDistributions, measures of central tendency and dispersion, confidence intervals, regression.	4–6
Ethics and Professional PracticeCodes of ethics, public health and safety, compliance with environmental regulations (CWA, CAA, RCRA and others), the engineer’s role in society.	5–8
Engineering EconomicsTime value of money, cost types, benefit-cost and life-cycle analysis, project selection.	5–8
Fundamental PrinciplesPopulation projections and demand, reactors (CSTR, batch, plug flow), materials science.	7–11
Environmental ChemistryStoichiometry and equilibrium, acid-base and precipitation, kinetics, organic chemistry, partitioning.	7–11
Health Hazards and Risk AssessmentDose-response toxicity, exposure routes and pathways, occupational health (PPE, noise).	4–6
Fluid Mechanics and HydraulicsWaterTied for the largest block on the exam. Statics, continuity and energy, closed-conduit and open-channel flow, pumps and blowers, flow measurement.	12–18
ThermodynamicsThe smallest block. First and second law, energy, heat and work, ideal gases.	3–5
Surface Water Resources and HydrologyWaterRunoff calculations such as the rational method, storage sizing, routing, erosion and stormwater quality, the water budget.	9–14
Groundwater, Soils, and SedimentsWaterDarcy's law, aquifers and well hydraulics, soil properties, contaminant fate and transport, remediation.	8–12
Water and WastewaterWaterTied for the largest block. Water quality, treatment unit processes, disinfection, biological treatment, sludge, conservation and reuse.	12–18
Air Quality and ControlEmissions, atmospheric dispersion, control technologies, indoor air, meteorology.	8–12
Solid and Hazardous WasteWaste management and recycling, landfills and leachate, hazardous-waste compatibility, site characterization, hazardous and radioactive waste treatment.	7–11
Energy and EnvironmentConventional and alternative energy sources and their environmental impact (greenhouse gases, carbon footprint, water needs).	4–6

The two largest blocks on the exam are Fluid Mechanics and Hydraulics and Water and Wastewater, tied at 12 to 18 questions each. Either one of them alone outweighs Air Quality and Control. Thermodynamics, at 3 to 5, is the smallest area on the exam. If you are budgeting study hours by how environmental a topic feels, this table will surprise you.

Check the date on your spec. NCEES still hosts an obsolete January 2014 FE Environmental specification alongside the current one, and it is easy to reach by searching. The blueprint in force is headed “Effective Beginning with the July 2020 Examinations”. If the document you are studying from does not say that, find the one that does.

For the pass-rate picture alongside this, the companion guide covers it: how hard is the FE Environmental exam?

Common questions

What do FE Environmental practice problems actually look like?: Mostly multiple choice with four options, usually phrased 'most nearly'. The options sit close enough that you cannot eliminate them by inspection, and on this exam several differ only in how one unit was converted. NCEES gives 110 questions in a 6-hour appointment, of which 5 hours 20 minutes is exam time, so the working time per question is under three minutes once you account for reading, a handbook lookup and a check. NCEES also uses alternative item types (multiple correct answers, point-and-click, drag-and-drop and fill-in-the-blank), each scored right or wrong with no partial credit.
Is the FE Environmental exam mostly water?: Not quite, but water is the biggest block. Four of the fifteen knowledge areas have water as their subject (Fluid Mechanics and Hydraulics, Water and Wastewater, Surface Water Resources and Hydrology, and Groundwater, Soils, and Sediments), and together they carry 41 to 51 of the 110 questions, 37 to 46 percent of the exam. Their ranges add to 62, but the fifteen area minimums already add to 100, so only 10 questions on any exam sit above them. Fluid Mechanics and Water and Wastewater are tied as the two largest blocks on the exam. Air Quality gets 8 to 12 and Solid and Hazardous Waste 7 to 11, which is fewer than most candidates assume. The grouping into 'water areas' is ours; the question ranges are NCEES's.
How many questions are on each FE Environmental topic?: The specification allocates 12-18 each to Fluid Mechanics and Hydraulics and to Water and Wastewater; 9-14 to Surface Water Resources and Hydrology; 8-12 each to Groundwater, Soils and Sediments and to Air Quality and Control; 7-11 each to Fundamental Principles, Environmental Chemistry, and Solid and Hazardous Waste; 5-8 each to Mathematics, Ethics and Professional Practice, and Engineering Economics; 4-6 each to Probability and Statistics, Health Hazards and Risk Assessment, and Energy and Environment; and 3-5 to Thermodynamics. The ranges sum to between 100 and 154 across the 15 areas against an exam of 110, so no single exam hits every maximum.
Am I looking at the right FE Environmental specification?: Check the date on it. NCEES still hosts an obsolete January 2014 specification alongside the current one, and it is easy to land on by searching. The blueprint in force is the one headed 'Effective Beginning with the July 2020 Examinations', and as of mid-2026 no revision to it has been announced. If the document you are studying from does not say July 2020, find the one that does.
What reference material do you get on the FE Environmental exam?: The exam is closed book with an electronic reference: the NCEES FE Reference Handbook is supplied on-screen as a searchable PDF, and you cannot bring your own copy or any outside material. Two habits pay off. Practice with the searchable PDF rather than a printed copy, because finding an equation is a timed skill. And check what the handbook actually contains for your weaker topics: its coverage is uneven, and some subjects the specification examines are thinner in the handbook than you would expect.

Build your study plan

Tell us how long you have. We'll budget your hours across every knowledge area using the official NCEES question weights. The heaviest areas get the most time, which is the opposite of how most people study.

Work through eight more

The free FE Environmental set has ten problems, eight of them not on this page: dose-response thresholds, normal distributions, pH, capital recovery, air-quality unit conversions and more, each with the full worked solution and the distractors named. No signup.

Try the free FE Environmental set Explore FE Environmental

Format, knowledge areas and appointment length are from the NCEES FE Environmental specification effective beginning with the July 2020 examinations. The per-question time and the grouping of four areas as “water” are ours, not NCEES figures. Specifications and fees change over time, so confirm current specifics at ncees.org. Independent study resource; not affiliated with, endorsed by, or sponsored by NCEES.