What do FE Environmental practice problems actually look like?

Multiple choice, four options, usually phrased 'most nearly' — the options sit close enough that you cannot eliminate them by inspection, and on this exam several will differ from each other only by a factor of ten. 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.

Is the FE Environmental exam mostly water?

Numerically, close to it. 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 by the specification's own ranges those four carry 41 to 62 of the 110 questions, or 37 to 56 percent of the paper. 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 sitting 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. Practise 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 a quarter of the paper. Four water areas are up to 56% of it. Here are three real problems from the parts that actually dominate — and a pattern in the wrong answers that is worth more than any of the three.

Updated August 31, 2026 · by the FE to PE Prep team

110

Questions

5h 20m

Exam time

Knowledge areas

37–56%

Water areas

The pattern in the wrong answers

Read the three solutions below and one thing repeats. On this exam almost nobody fails because they could not remember an equation — the handbook prints the equations, and the exam supplies it. They fail on what gets fed into it.

The distractors are substitution errors, not formula errors. A dropped coefficient, an inverted ratio, a unit factor a decade out. Each produces a complete, believable number that no amount of re-reading the formula will catch.
Some wrong answers are the right answer to a different question. Omit the area from Darcy’s law and you have correctly computed the Darcy velocity. It is a real quantity, correctly calculated, with the wrong dimensions — and that is far harder to spot than a slip.
Order of magnitude is the exam’s favourite trap. In the rational-method problem three of the four options are the same digits in different decimal places. A sanity check on magnitude 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 real 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 first hydrology equation most candidates learn and the one this exam is most likely to hand you. The formula is printed for you, unit factor and all. Notice what the options do anyway.

1
easy
A. Runoff & water budget
An urban catchment of area $A = 12$ ha has a runoff coefficient $C = 0.7$ . During a design storm the rainfall intensity is $i = 90$ mm/h. Using the rational method $Q = 0.00278\,C\,i\,A$ (Q in m³/s, i in mm/h, A in ha), the peak runoff is most nearly:
1. 0.21 m³/s
2. 21 m³/s
3. 2.1 m³/s
4. 3 m³/s
Show the answer & worked solution
Answer: C.2.1 m³/s
$Q = 0.00278\,C\,i\,A = 0.00278(0.7)(90)(12) = 2.102$ m³/s. Distractors: the runoff coefficient $C$ OMITTED (treated as 1); the unit factor a decade too large (0.0278 instead of 0.00278); and the factor derived as $1/3600 = 0.000278$ instead of $1/360 = 0.00278$ (the mm/h→m/s conversion taken a decade too small).

What the distractors teach: Look at the four numbers: 0.21, 2.1, 21 and 3. Three of them are the same digits in different decimal places, and that is the entire question. Drop the runoff coefficient and treat C as 1: you get 3. Take the unit factor a decade too large, 0.0278 instead of 0.00278: you get 21. Derive it as 1/3600 rather than 1/360: you get 0.21. Nobody here has forgotten the equation. Every one of them has lost a factor of ten inside it, and a runoff figure ten times too small 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 $D_2 = 100$ mm. The upstream velocity is $V_1 = 2$ m/s. The velocity in the smaller section is most nearly:
1. 1 m/s
2. 32 m/s
3. 4 m/s
4. 8 m/s
Show the answer & worked solution
Answer: D.8 m/s
Continuity $A_1V_1=A_2V_2$ with $A\propto D^2$ gives $V_2=V_1(D_1/D_2)^2=2\,(200/100)^2=8$ m/s. Distractors: the diameter ratio raised to the FOURTH power ( $V_1(D_1/D_2)^4$ , the area-ratio squaring applied a second time); the DIAMETER ratio used un-squared ( $V_1 D_1/D_2$ , forgetting $A\propto D^2$ ); and the ratio both inverted and un-squared ( $V_1 D_2/D_1$ ).

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 4 m/s. Square it twice — applying the area relationship a second time by reflex — and you get 32 m/s. Invert the ratio and leave it un-squared and you get 1 m/s, a contraction that somehow slows the water down. That last one is worth a second of thought, because it is the only option that a physical sanity check kills on its own.

3. Aquifer discharge by Darcy's law

Darcy's law is three symbols long and the handbook prints it. This problem is here because the most dangerous distractor on it is not a wrong number — it is the right number for a different quantity.

3
easy
A. Darcy's law & hydrogeology
A confined sand aquifer carries flow between two wells that are $L = 60$ m apart with a head difference of $\Delta h = 3$ m. The hydraulic conductivity is $K = 12$ m/d and the flow cross-section is $A = 50$ m². The volumetric discharge is most nearly:
1. 0.6 m³/d
2. 12000 m³/d
3. 1800 m³/d
4. 30 m³/d
Show the answer & worked solution
Answer: D.30 m³/d
$i = \Delta h/L = 3/60 = 0.05$ , so $Q = K\,i\,A = 12\cdot0.05\cdot50 = 30$ m³/d. Distractors: the cross-sectional area OMITTED ( $K\,i$ , which is the Darcy velocity, not a discharge); the gradient INVERTED ( $L/\Delta h$ used for $i$ ); and the head drop $\Delta h$ used directly as the gradient (the division by the flow-path length $L$ dropped).

What the distractors teach: Omit the cross-sectional area and you compute K·i, which is 0.6 — the Darcy velocity. That is a real, correctly calculated quantity with the wrong dimensions for the question, and unlike an arithmetic slip it will not look wrong to you. The other two are gradient errors: invert i to L/Δh and you get 12,000, or use the head drop of 3 m directly as the gradient without dividing by the 60 m flow path and you get 1,800. The gradient is dimensionless. If your i has units, you have already gone wrong.

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 — that grouping is ours, but the numbers are theirs, and together those four carry 41 to 62 questions of the 110.

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, agreements and contracts, professional liability, public health and safety.	5–8
Engineering EconomicsTime value of money, cost estimation, life-cycle and benefit-cost analysis.	5–8
Fundamental PrinciplesMass and energy balances, stoichiometry, reaction kinetics, transport.	7–11
Environmental ChemistryEquilibrium, pH and alkalinity, solubility, organic chemistry, partitioning.	7–11
Health Hazards and Risk AssessmentDose-response, exposure pathways, toxicology, epidemiology, risk characterisation.	4–6
Fluid Mechanics and HydraulicsWaterTied for the largest block on the exam. Statics, continuity and energy, pipe flow and networks, pumps, open-channel flow, flow measurement.	12–18
ThermodynamicsThe smallest block. Properties, first and second law, psychrometrics, combustion.	3–5
Surface Water Resources and HydrologyWaterPrecipitation and runoff, the rational method, hydrographs, routing, reservoirs, erosion and sedimentation.	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, collection and distribution.	12–18
Air Quality and ControlEmissions, atmospheric dispersion, control technologies, indoor air, meteorology.	8–12
Solid and Hazardous WasteCharacterisation, landfills, incineration, radioactive decay, site assessment, the regulatory framework.	7–11
Energy and EnvironmentEnergy sources and conversion, efficiency, climate and sustainability.	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 paper. 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?: Multiple choice, four options, usually phrased 'most nearly' — the options sit close enough that you cannot eliminate them by inspection, and on this exam several will differ from each other only by a factor of ten. 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.
Is the FE Environmental exam mostly water?: Numerically, close to it. 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 by the specification's own ranges those four carry 41 to 62 of the 110 questions, or 37 to 56 percent of the paper. 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 sitting 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. Practise 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 seven more

Ten free FE Environmental problems in total — dose-response thresholds, normal distributions, pH, capital recovery, waste generation rates — 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 — confirm current specifics at ncees.org. Independent study resource; not affiliated with, endorsed by, or sponsored by NCEES.