Is the PE Civil Water Resources exam all water engineering?

No, and the gap is larger than the name suggests. Four of the twelve areas are not water or environmental engineering at all (Project Sitework, Materials, Project Planning and Soil Mechanics), and by our arithmetic on the specification's ranges they account for 20 to 30 of the 80 questions (their maxima add to 31, but the other areas' minimums take 50). Project Sitework alone is the single largest knowledge area on the exam, larger than Hydrology. A candidate who prepares only hydraulics, hydrology and treatment leaves a quarter to three-eighths of the exam uncovered.

How long is the PE Civil exam and how many questions?

Eighty questions in a 9-hour appointment, of which 8 hours is exam time; the 50-minute scheduled break does not come out of those 8 hours. Across 80 questions that is 6 minutes each, our own arithmetic rather than a figure NCEES publishes. It is roughly double the working time per question the FE allows, because PE questions are longer and more design-like, not because the exam is more generous.

Is the PE Civil Water Resources specification changing?

Yes. The specification effective April 2024 runs through the March 2027 administrations. NCEES has already published a revised design-standards list that takes effect with the April 2027 examination; the knowledge areas and question ranges do not change. If you are taking the exam in 2026 or early 2027 the current specification applies; if you are buying prep material now for an exam after that date, check which specification it was written against, because the design standards are what changed.

What reference material do you get on the PE Civil exam?

The exam is closed book with an on-screen searchable reference: the NCEES PE Civil Reference Handbook, together with the design standards the specification lists. For the Water Resources and Environmental depth that is the two Ten States Standards, Recommended Standards for Water Works (2018) and Recommended Standards for Wastewater Facilities (2014). Those are the editions for exams through March 2027; for exams from April 2027 NCEES has posted a longer list of seven documents, with the water-works standard in its 2022 edition. You cannot bring your own copy. Practicing against the searchable PDF rather than a printed copy matters more than candidates expect, because locating an equation under time pressure is a distinct skill from knowing it.

PE Civil Water Resources: what the exam actually covers

The largest single knowledge area on the PE Civil Water Resources and Environmental exam is Project Sitework: excavation, grading, retaining walls, construction methods. It is bigger than Hydrology. It is bigger than either hydraulics block. Read the NCEES specification by family rather than by row and between 20 and 30 of the 80 questions turn out not to be water engineering at all.

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

Questions

Exam time

Knowledge areas

~6 min

Per question

A quarter of the exam is not what its name says

Eight of the twelve areas are water and environmental engineering, and together they carry between 50 and 60 questions. The other four (Project Sitework, Materials, Project Planning and Soil Mechanics) carry between 20 and 30. That is a construction-engineering block, a geotechnical block, and a project-management block, sitting inside a depth exam that is easy to prepare for as though it were hydraulics and treatment.

Project Sitework is the biggest area on the exam. Nine to fourteen questions on grading and cut-and-fill, site layout, erosion and sediment control, safety, curve elements, retaining walls and construction methods. Only the erosion and sediment control is environmental in any real sense.
Soil Mechanics and Materials are seven to eleven more. Lateral earth pressure, consolidation, bearing capacity, settlement, slope stability, soil classification and boring logs, concrete, piping materials. That is a geotechnical exam in miniature, and it is worth at least as much as Drinking Water Distribution and Treatment (6–9).
Project Planning is four to six. Quantity take-off, cost estimating, schedules, sequencing, present worth and lifecycle comparison, the same material an estimator uses, and none of it in the reference handbook's hydraulics chapters.
It is six minutes a question, not three. Eight hours of exam time across 80 questions is about double the FE's time per question. That is not generosity: PE questions are longer, more design-like, and expect fluent movement between the handbook and the design standards.

Three practice problems

One from Project Sitework, one from Soil Mechanics, one from Open-Channel Hydraulics. Two of the three are from areas this exam is not named after, which is the point. All drawn from our free PE Civil Water Resources set. Read the distractor notes rather than just the answer: on this exam the wrong options are engineered, not random.

1. Borrow volume for an embankment

Project Sitework is the largest knowledge area on this exam: 9 to 14 of the 80 questions, more than Hydrology and more than either hydraulics block. This is one of them: a levee, and not a drop of water in the calculation.

1
medium
A. Earthwork, curves & retaining sitework
A levee embankment is built of compacted fill. Its fill end areas are $410\,\text{ft}^2$ at Sta 20+00 and $530\,\text{ft}^2$ at Sta 23+00. The borrow soil has a shrinkage of 18%: it loses 18% of its bank volume when compacted. The bank (in-situ) volume that must be excavated from borrow for this reach (CY) is most nearly:
1. 4,280 CY
2. 5,220 CY
3. 6,160 CY
4. 6,370 CY
Show the answer & worked solution
Answer: D.6,370 CY
The compacted volume of the reach comes from the average end area (§2.1.2.1 Cross-Section Methods), with $L=300$ ft between the sections: $V_C=L\,\dfrac{A_1+A_2}{2}=300\cdot\dfrac{410+530}{2}=141{,}000\,\text{ft}^3$ , and $141{,}000/27=5{,}222.2$ CY. Shrinkage is a share of the bank volume (§2.1.1 Excavation and Embankment): $V_C=(1-S_h/100)\,V_B$ . With $s=S_h/100=0.18$ , $V_B=\dfrac{V_C}{1-s}=\dfrac{5{,}222.2}{1-0.18}=6{,}369$ CY. Distractors: MULTIPLIED the compacted volume by $(1-s)$ instead of dividing (4,282 CY), less bank soil than the fill it has to make; IGNORED the shrinkage and reported the compacted volume itself (5,222 CY); and took the 18% as a share of the fill and grossed it up, $V_C(1+s)$ (6,162 CY), when it is a share of the bank volume.

What the distractors teach

Two handbook steps, and every wrong answer is in the second. The average end area gives the compacted fill in the reach: 300 ft × (410 + 530)/2 = 141,000 ft³, or 5,222 CY. 6,160 CY, the closest, multiplies that fill by 1.18. The stem says the soil loses 18% of its bank volume when compacted, which is the handbook's own definition, $V_C=(1-s)\,V_B$ , so the bank is the fill divided by 0.82: 6,370 CY. Published definitions vary; the handbook notes that unless a question says otherwise, exam questions use the swell and shrinkage formulas it prints. 4,280 CY multiplies by (1 − s) instead of dividing, which returns less borrow than the fill it has to produce. That is physically backwards: with a positive shrinkage, compaction always consumes more bank volume than it places. 5,220 CY ignores the 18% altogether. One number, three ways to misread it.

2. Ultimate bearing capacity of a strip footing

Soil Mechanics is the smallest area on the exam at 3 to 5 questions, and it is still geotechnical engineering, on an exam named for water. Three terms in the equation, three chances to lose the point.

2
medium
A. Lateral earth pressure & bearing capacity
A continuous (strip) footing of width $B=7\,\text{ft}$ is founded at depth $D_f=3\,\text{ft}$ in soil with cohesion $c=400\,\text{psf}$ , friction angle $\phi=32^\circ$ , and unit weight $\gamma=120\,\text{pcf}$ . Assume the same soil above and below the base, no surface surcharge, and no groundwater within the zone of influence. Using the bearing capacity factors in the PE Civil Reference Handbook, the ultimate (gross) bearing capacity $q_{ult}$ is most nearly:
Figure — drag or pinch to move around
1. 26,900 psf
2. 35,200 psf
3. 39,100 psf
4. 47,900 psf
Show the answer & worked solution
Answer: B.35,200 psf
Strip-footing bearing capacity equation (§3.4.2), with the Bearing Capacity Factors table row at $\phi=32^\circ$ : $N_c=35.5$ , $N_q=23.2$ , $N_\gamma=30.2$ ; $q=\gamma D_f=120(3)=360$ psf. $q_{ult}=cN_c+qN_q+\tfrac12\gamma B N_\gamma=400(35.5)+360(23.2)+\tfrac12(120)(7)(30.2)=14{,}200+8{,}352+12{,}684=35{,}236$ psf. Distractors: DROPPED the ½ on the $\gamma B N_\gamma$ term ( $47{,}900$ ); SWAPPED $B$ and $D_f$ between the $N_q$ and $N_\gamma$ terms ( $39{,}100$ ; reading a textbook's Terzaghi factors in place of the handbook's table lands here too); and omitted the $qN_q$ surcharge term, as if the footing sat at the ground surface ( $26{,}900$ ).

What the distractors teach

The equation is right in all four options; only the handling of one term differs. 47,900 psf drops the ½ on the $\tfrac{1}{2}\gamma B N_\gamma$ term, the most common slip with this equation, and it inflates the answer by more than a third. 39,100 psf swaps $B$ and $D_f$ between the $N_q$ and $N_\gamma$ terms, which is easy to do because both are lengths and both multiply $\gamma$ . 26,900 psf leaves out the $\gamma D_f N_q$ surcharge term entirely, as if the footing sat on the ground surface. Checking your arithmetic finds none of these. One more trap sits outside the equation: a textbook's Terzaghi factors in place of the handbook's table land at roughly 39,000 to 40,000 psf, nearest the swapped option.

3. Uniform discharge in a trapezoidal channel

Open-channel hydraulics is 7 to 11 questions and Manning is its workhorse. The equation is printed for you in the handbook. Describing the channel correctly is up to you.

3
medium
A. Uniform flow, specific energy & critical depth
An earthen trapezoidal irrigation canal has a bottom width $b=8\,\text{ft}$ , side slopes $z=2$ (H:V), and runs at a normal depth $y=3\,\text{ft}$ on a slope $S=0.0005$ with Manning $n=0.025$ . The uniform discharge is most nearly:
Figure — drag or pinch to move around
1. 34.4 cfs
2. 87.5 cfs
3. 91.5 cfs
4. 116 cfs
Show the answer & worked solution
Answer: B.87.5 cfs
Manning's equation (§6.4.5.1), with the trapezoid's area and wetted perimeter from the Geometric Elements of Channel Sections table (§6.4.5.4): $A=(b+zy)y=(8+2\cdot3)3=42$ ft², $P=b+2y\sqrt{1+z^2}=8+2(3)\sqrt{1+2^2}=21.416$ ft, $R=A/P=1.961$ ft. $Q=\frac{1.486}{n}AR^{2/3}S^{1/2}=\frac{1.486}{0.025}(42)(1.961)^{2/3}(0.0005)^{1/2}=87.5$ cfs. Distractors: used the RECTANGLE area $b y$ , dropping the side triangles ( $34.4$ ); used $P=b+2y$ , omitting $\sqrt{1+z^2}$ on the slanted sides ( $116$ ); and took the wetted perimeter as $b+2zy=20$ ft, the horizontal run of the side slopes (the top width), instead of their slant length ( $91.5$ ).

What the distractors teach

Not one wrong answer misuses Manning's equation; they all misdescribe the channel. 34.4 cfs uses the rectangle b·y and discards the two side triangles, which on a 2:1 side slope are 18 of the 42 ft² of flow area: 43% of the section, thrown away. 116 cfs takes P = b + 2y, measuring the sloped sides as if they were vertical. 91.5 cfs measures them along their horizontal run, P = b + 2zy: on a 2:1 slope the run is only 11% shorter than the slant, so this one lands within 5% of the right answer. The wetted perimeter runs along the real slope, y√(1+z²) on each side. The difficulty in an open-channel question is almost never the equation.

Where the 80 questions come from

NCEES publishes a question range for every knowledge area in its exam specification. In our view it is the most useful study document there is, and it is free. The ranges are wide and sum to between 70 and 108 across the twelve areas against an exam of 80, so no single exam hits every maximum. The minimums alone take 70 questions and leave 10 to share out, which means no group of areas can go more than 10 above its own minimums. The ordering holds, though, and it tells you where your hours belong.

PE Civil Water Resources and Environmental knowledge areas and question counts, per the NCEES specification effective April 2024
Knowledge area	Questions
Project Siteworknot waterThe largest area on the exam. Excavation and embankment, site layout and control, erosion and sediment control, impact on adjacent facilities, safety, horizontal and vertical curve elements, retaining walls, construction methods. Erosion and sediment control is genuinely environmental; the rest is construction engineering.	9–14
HydrologyStorm characteristics, Rational and SCS/NRCS runoff, hydrograph development including synthetic hydrographs, intensity–duration–frequency, time of concentration, gauging, depletions, and stormwater management.	8–12
Hydraulics — Closed ConduitEnergy and continuity, pressure conduit with Hazen-Williams and Darcy-Weisbach, major and minor losses, pumps including wet wells and cavitation, and pipe network analysis.	7–11
Hydraulics — Open ChannelOpen-channel flow, hydraulic grade lines and energy dissipation, stormwater collection and drainage, culverts and gutter flow, and sub- versus supercritical flow.	7–11
Wastewater Collection and TreatmentCollection systems and lift stations, preliminary through secondary treatment, nutrient removal, solids handling and disposal, disinfection, and advanced treatment.	7–11
Analysis and DesignMass balance, hydraulic loading, solids loading, and hydraulic flow measurement: the process arithmetic that sits underneath both treatment areas.	6–9
Drinking Water Distribution and TreatmentDemand and storage, distribution systems, and the treatment train through to disinfection and residuals.	6–9
Surface Water and Groundwater QualityStream degradation and oxygen dynamics, total maximum daily load, and biological and chemical contaminants.	5–8
Groundwater and WellsAquifer behavior, well hydraulics and drawdown, and groundwater transport.	4–6
Materialsnot waterSoil classification and boring logs, soil strength and permeability and phase relations, concrete, piping materials, and test methods with specification conformance.	4–6
Project Planningnot waterQuantity take-off, cost estimating, schedules, activity sequencing, and economic and lifecycle analysis. Project management, not hydraulics.	4–6
Soil Mechanicsnot waterLateral earth pressure, consolidation and compaction, bearing capacity, settlement, slope stability. The smallest area, and pure geotechnical engineering.	3–5

Areas and ranges are NCEES's, verbatim. The “not water” tag is our own reading of the published subtopics, not an NCEES label.

Read that table by family. The eight water and environmental areas start at 50 questions between them and run to 60. The four that are not (Project Sitework, Materials, Project Planning, Soil Mechanics) start at 20 and run to 30. On an 80-question exam that is a quarter to three-eighths of your points sitting outside the subject on the exam's own title, and it is the allocation mistake worth avoiding: a water engineer studying only water is under-preparing for the largest single area on the exam.

The specification changes in April 2027

The specification described on this page took effect in April 2024 and runs through the March 2027 administrations. NCEES has already published the revision that replaces it, effective with the April 2027 examination. The twelve knowledge areas and their ranges stay the same; what changes is the design standards the exam is written against. The list grows from the two Ten States Standards to seven documents, adding OSHA's construction regulations (29 CFR 1926, selected subparts), the USACE slope-stability manual, FHWA's HDS-5 culvert and HEC-14 energy-dissipator manuals and a UFC dewatering manual, and the water-works standard moves to its 2022 edition.

That matters if you are buying prep material now for a later exam date. A question bank or review course assembled against the current standards is correct for every administration up to March 2027 and progressively less so after it. Check which specification any material names before you pay for access that runs past that date, ours included.

Common questions

What is on the PE Civil Water Resources and Environmental exam?: Eighty questions drawn from twelve knowledge areas. By the NCEES specification the allocation is 9-14 questions to Project Sitework; 8-12 to Hydrology; 7-11 each to Closed-Conduit Hydraulics, Open-Channel Hydraulics, and Wastewater Collection and Treatment; 6-9 each to Analysis and Design and to Drinking Water Distribution and Treatment; 5-8 to Surface Water and Groundwater Quality; 4-6 each to Groundwater and Wells, Materials, and Project Planning; and 3-5 to Soil Mechanics. The ranges are wide on purpose. They sum to between 70 and 108 against an exam of 80, so no single exam hits every maximum.
Is the PE Civil Water Resources exam all water engineering?: No, and the gap is larger than the name suggests. Four of the twelve areas are not water or environmental engineering at all (Project Sitework, Materials, Project Planning and Soil Mechanics), and by our arithmetic on the specification's ranges they account for 20 to 30 of the 80 questions (their maxima add to 31, but the other areas' minimums take 50). Project Sitework alone is the single largest knowledge area on the exam, larger than Hydrology. A candidate who prepares only hydraulics, hydrology and treatment leaves a quarter to three-eighths of the exam uncovered.
How long is the PE Civil exam and how many questions?: Eighty questions in a 9-hour appointment, of which 8 hours is exam time; the 50-minute scheduled break does not come out of those 8 hours. Across 80 questions that is 6 minutes each, our own arithmetic rather than a figure NCEES publishes. It is roughly double the working time per question the FE allows, because PE questions are longer and more design-like, not because the exam is more generous.
Is the PE Civil Water Resources specification changing?: Yes. The specification effective April 2024 runs through the March 2027 administrations. NCEES has already published a revised design-standards list that takes effect with the April 2027 examination; the knowledge areas and question ranges do not change. If you are taking the exam in 2026 or early 2027 the current specification applies; if you are buying prep material now for an exam after that date, check which specification it was written against, because the design standards are what changed.
What reference material do you get on the PE Civil exam?: The exam is closed book with an on-screen searchable reference: the NCEES PE Civil Reference Handbook, together with the design standards the specification lists. For the Water Resources and Environmental depth that is the two Ten States Standards, Recommended Standards for Water Works (2018) and Recommended Standards for Wastewater Facilities (2014). Those are the editions for exams through March 2027; for exams from April 2027 NCEES has posted a longer list of seven documents, with the water-works standard in its 2022 edition. You cannot bring your own copy. Practicing against the searchable PDF rather than a printed copy matters more than candidates expect, because locating an equation under time pressure is a distinct skill from knowing it.

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 PE Civil Water Resources problems in total, among them Rational-method peak flow, Hazen-Williams head loss, BOD removal, a BOD loading in lb/day, peaking factors, seepage velocity and degree of saturation, every one with the full worked solution. No signup.

Try the free PE Civil WRE set Explore PE Civil WRE

Knowledge areas, question counts and format are from the NCEES PE Civil: Water Resources and Environmental CBT exam specification effective beginning April 2024; the April 2027 changes are from the revised design-standards list NCEES posted in 2026. The per-question time and the water / not-water split of the twelve areas are our own, not NCEES figures. NCEES's pass rates for every PE Civil depth are compared in how hard is the PE Civil exam?. 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.