How hard is the Water Resources and Environmental depth?
It has the highest first-time pass rate of the five PE Civil depths: 71% of 2,620 first-time takers passed, on NCEES's July 2026 figures. Repeat takers passed at 49%, so a first attempt prepared properly matters.
Questions
80, all worked
Exam time
8 hours in a 9-hour appointment
Delivery
Computer-based, year round
References
Handbook and design standards on screen
First-time pass rate
71%
What makes it hard
Breadth: twelve knowledge areas, from pipe networks and hydrographs to activated sludge, earthwork and engineering economics.
Pace: 8 hours of exam time for 80 questions is 6 minutes a question, with the calculation and the units included.
Finding the relation: the handbook and design standards are searchable PDFs on screen, and only one standard chapter can be open at a time.
Both unit systems: questions use SI and US customary units.
What makes it manageable
Most questions are calculations with one right number, so steady practice pays off directly.
The relations repeat: continuity, energy, Manning, the rational method, mass balance and the pounds formula carry a large share of the exam.
The exam is offered year round, so you can book when your practice scores are steady.
Where the 80 questions come from
Knowledge area
Questions
1. Project Planning
4 to 6
2. Soil Mechanics
3 to 5
3. Materials
4 to 6
4. Analysis and Design
6 to 9
5. Hydraulics: Closed Conduit
7 to 11
6. Hydraulics: Open Channel
7 to 11
7. Hydrology
8 to 12
8. Groundwater and Wells
4 to 6
9. Surface Water and Groundwater Quality
5 to 8
10. Drinking Water Distribution and Treatment
6 to 9
11. Wastewater Collection and Treatment
7 to 11
12. Project Sitework
9 to 14
Try 4 questions
Question 1Pipe friction and minor losses
A 12-in. ductile iron water main 3,000 ft long carries 3.0 cfs. Apply the Hazen-Williams equation in the form hf = 4.73 L Q1.852 / (C1.852 D4.87), with hf and L in ft, Q in cfs and D in ft, and C = 120. The friction head loss is most nearly:
Question 2Runoff: rational and curve number methods
A 20.0 ac drainage area consists of 8.0 ac of roofs and pavement (C = 0.90), 9.0 ac of lawn (C = 0.20) and 3.0 ac of woods (C = 0.15). The design rainfall intensity for a duration equal to the time of concentration is 3.2 in./h. Using Q = CiA with 1 ac-in./h = 1.008 ft3/s, the peak runoff is most nearly:
Question 3Secondary treatment and activated sludge
An activated sludge basin of 4,000 m3 holds mixed liquor at 3,000 mg/L of suspended solids. Waste sludge leaves from the return line at 100 m3/d and 9,000 mg/L, and the clarifier effluent of 15,000 m3/d carries 15 mg/L of suspended solids. The solids retention time, counting solids lost in both streams, is most nearly:
Question 4Horizontal and vertical curves
A horizontal curve has a radius of 1,200 ft and a deflection angle of 38 deg 24 min. The PI is at station 45+62.40. The station of the PT, measured along the curve, is most nearly:
Is the Water Resources and Environmental depth the easiest PE Civil depth?
It had the highest first-time pass rate of the five depths in NCEES's July 2026 figures: 71%, against 60% to 63% for the others. Difficulty still depends on how well your experience covers its twelve areas.
How long is the exam?
A 9-hour appointment: a 2-minute nondisclosure agreement, an 8-minute tutorial, 8 hours of exam time and a 50-minute scheduled break.
What score do I need to pass?
NCEES does not publish a passing score, so we do not estimate one. Our mock reports questions right by knowledge area.