What is on the FE Environmental exam?

The FE Environmental exam has 110 questions with a time limit of 5 hours and 20 minutes. NCEES divides it into 15 knowledge areas under the specification in effect since July 2020. The exam is closed book, but you get an electronic reference during the test. Water and Wastewater and Fluid Mechanics and Hydraulics are the largest areas, each with 12 to 18 questions. Surface Water Resources and Hydrology follows, at 9 to 14 questions.

Question ranges on the environmental specification

NCEES assigns every knowledge area a range of questions, so the count on your form can move within that range. In every FE specification, the low ends of the ranges add up to 100 of the 110 questions, and the other 10 questions go to areas that run above their minimums. The table below shows those ranges for the FE Environmental specification.

Where the larger ranges fall

The highest ranges are treatment, hydraulics, and hydrology, with groundwater and air in the next tier. The notes below use the official area names and describe the work in plain language.

Water and wastewater

Water and Wastewater is tied for the most questions, at 12 to 18. Items start from physical, chemical, and biological characteristics of the flow, including nutrients, and then ask for a mass balance, a loading rate, or a removal efficiency. Physical treatment includes clarification, filtration, membranes, adsorption, flocculation, headworks, flow equalization, air stripping, and activated carbon. Chemical treatment includes disinfection, ion exchange, softening, coagulation, and precipitation, while biological treatment includes activated sludge, fixed film, lagoons, phytoremediation, and aerobic, anoxic, and anaerobic conditions. Sludge questions cover digestion, dewatering, composting, and land application, and the area can also include conservation and reuse. Drill clarifier overflow rate and detention time until basin geometry and units are quick.

Fluid mechanics and hydraulics

Fluid Mechanics and Hydraulics is the other 12 to 18 question block. Statics items ask for pressure and for force on a surface, while pipe items use Darcy-Weisbach, Hazen-Williams, and a Moody friction factor. Open-channel items use Manning’s equation, subcritical and supercritical flow, culverts, and the hydraulic elements of the section. Pumps and blowers are framed with power, efficiency, inlet and outlet pressure, the operating point, and units in parallel or in series, and measurement devices include weirs, orifices, and flumes. Dynamics items use Bernoulli, continuity, laminar and turbulent flow, and both steady and unsteady conditions. Pipe flow head loss (Darcy-Weisbach) is worth repeating, because the same friction steps show up in plant piping.

Surface water, groundwater, and air

Surface Water Resources and Hydrology is 9 to 14 questions. Runoff depends on land use and cover, time of concentration, and storm duration, intensity, and frequency, along with controls that manage that runoff. Storage problems size reservoirs and detention or retention basins, and routing moves a flood wave through a channel or a reservoir. Quality and modeling work includes erosion, channel stability, stormwater quality, wetlands, dissolved-oxygen sag along a stream, and nutrient enrichment. A water budget connects precipitation, evapotranspiration, infiltration, soil moisture, and storage.

Groundwater, Soils, and Sediments is 8 to 12 questions. You need aquifer and soil properties, Darcy’s law, specific capacity, velocity, gradient, and transport. Drawdown items use the Dupuit, Jacob, Theis, and Thiem relations. Remediation covers recovery and treatment of soil, sediment, or groundwater, either in place or after removal.

Air Quality and Control is also 8 to 12 questions. Coverage includes ambient and indoor air for criteria pollutants and for toxic or hazardous air pollutants, mass and energy balances (including an STP basis, loadings, and heating values), and emission factors and rates. Meteorology appears as stability class, lapse rate, and dispersion. Gas treatment includes biofiltration, scrubbers, adsorbers, incineration, and catalytic reducers, while particle treatment includes baghouses, cyclones, and electrostatic precipitators. Indoor items use air-exchange rates and a reactor model at steady conditions or while concentration is still changing.

Chemistry, waste, fundamentals, and shorter areas

Three areas share a 7 to 11 question range: Environmental Chemistry, Fundamental Principles, and Solid and Hazardous Waste.

Environmental Chemistry asks you to balance reactions and apply equilibrium to acids and bases, oxidation-reduction, and precipitation, then to use kinetics for chemical conversion, growth, or decay. Organic items stay with naming and functional-group reactions, and partitioning items ask how a chemical divides among phases, using ideas such as Henry’s law and an octanol partitioning coefficient.

Fundamental Principles covers population and demand projections for water, wastewater, solid waste, and energy, plus reactors, material properties, corrosion, compatibility, and stress-strain behavior.

Solid and Hazardous Waste covers mass and energy balances, collection and transport, storage, composting, recycling, waste-to-energy, landfill disposal with leachate and gas collection, hazardous-waste compatibility, sampling and remedial investigation, and physical, chemical, thermal, or biological treatment of hazardous and radioactive waste.

Health Hazards and Risk Assessment and Energy and Environment are each 4 to 6 questions. Health items move from dose-response for carcinogens and noncarcinogens, to exposure routes and pathways, to occupational controls such as protective equipment, noise, and safety screening. Energy items cover conventional and alternative sources and the impacts of producing that energy, including greenhouse gases, carbon footprint, heat releases, and water needs. Thermodynamics is the shortest range, at 3 to 5 questions, and it still includes the first and second laws, heat, work, efficiencies, coefficients of performance, cycles, conduction, convection, radiation, and ideal-gas behavior.

Mathematics, statistics, ethics, and economics

Mathematics (5 to 8), Probability and Statistics (4 to 6), Ethics and Professional Practice (5 to 8), and Engineering Economics (5 to 8) are on this exam and on every other FE exam. Which topics are on every FE exam compares those shared areas. The specifications for all seven disciplines have been in effect since the July 2020 examinations.

Mathematics here is analytic geometry, trigonometry, equations and roots, differential and integral calculus, differential equations, and numerical methods such as approximate integration, precision limits, and error propagation. Probability and Statistics covers center and spread, discrete and continuous distributions (including normal and binomial), a point estimate and a confidence interval for a single mean, linear and multiple regression with a goodness-of-fit check, and hypothesis tests such as a t-test, an outlier test, or an analysis of variance.

Ethics and Professional Practice includes society codes of ethics, the duty to public health, safety, and welfare, licensing boards, and professional liability. Compliance questions can draw on CWA, CAA, RCRA, CERCLA, SDWA, NEPA, or OSHA. The same area includes the engineer’s role in society: sustainability, resiliency, and long-term viability.

Engineering Economics is the time value of money, written as present worth, annual worth, future worth, rate of return, and annuities. It also covers fixed, variable, direct, indirect, incremental, average, and sunk costs, plus operations and maintenance. Analyses include benefit-cost, break-even, minimum cost, overhead, and life cycle. Project selection includes unequal lives, lease versus buy versus make, depreciation, and discounted cash flow.

Handbook chapters for this exam

Your electronic reference during the exam is the FE Reference Handbook. The pages below show where chapters start in the printed handbook 10.6, but learn the chapter names, since the copy at the test center is electronic.

• Environmental Engineering, page 318
• Fluid Mechanics, page 181
• Chemical Engineering, page 243, and Civil Engineering, page 265 (these two chapters start just before Environmental Engineering)
• Chemistry and Biology, page 86
• Thermodynamics, page 143, and Heat Transfer, page 209
• Materials Science, page 117, and Mechanics of Materials, page 130
• Mathematics, page 36, and Engineering Probability and Statistics, page 64
• Ethics and Professional Practice, page 4; Safety, page 15; Engineering Economics, page 235; Units and Conversion Factors, page 1

For on-the-job hazard items, Safety is the chapter to open alongside ethics. Practice finding relations in the electronic book before exam day, the habit that How to use the FE Reference Handbook during the exam covers, so these page numbers stay useful under a time limit.

Pass rate on the NCEES table

The NCEES pass-rate table, last updated July 2026, reports first-time takers by discipline. For FE Environmental, the volume is 1,063 and the pass rate is 71%, a result specific to that group of examinees. The same update lists the other FE disciplines on the FE exam pass rate page.

A study order from the ranges

NCEES publishes the ranges. The weekly order is yours. We suggest you study the high ranges first and keep the short ranges on a repeating rotation so they stay fresh. One way to split the specification:

1. Water and Wastewater, together with Fluid Mechanics and Hydraulics.
2. Surface Water Resources and Hydrology.
3. Groundwater, Soils, and Sediments, together with Air Quality and Control.
4. Environmental Chemistry, Fundamental Principles, and Solid and Hazardous Waste.
5. Mathematics, Probability and Statistics, Ethics and Professional Practice, Engineering Economics, Health Hazards and Risk Assessment, Energy and Environment, and Thermodynamics.

Lay that order on a calendar such as a 60-day study plan for the FE exam. In each practice session, use the handbook you will have on exam day, and redo any problem where the slow part was finding the relation. Keep every area in the rotation, since questions can land above the range minimums, and Thermodynamics can be 3 questions on one form and 5 on another while it is still on the exam.

Frequently asked questions

How many questions are on the FE Environmental exam?

The exam has 110 questions, and the time limit is 5 hours and 20 minutes. NCEES sorts them into 15 knowledge areas, each with a range rather than one fixed count. The low ends of those ranges add up to 100 questions, and the other 10 are placed inside the published ranges.

What is the hardest part of the FE Environmental exam?

The specification tells you how many questions each area can carry, but it gives no separate difficulty rank. The largest ranges are Water and Wastewater and Fluid Mechanics and Hydraulics, both 12 to 18 questions, followed by Surface Water Resources and Hydrology at 9 to 14. Slow work in those areas touches more items than Thermodynamics, which is 3 to 5 questions, so prioritize the large ranges and still cover the full specification.

What is the FE Environmental pass rate?

In the NCEES table last updated July 2026, the FE Environmental pass rate for first-time takers is 71%, from a volume of 1,063 examinees. That figure describes that group in that update, so use it as context for the discipline while you prepare every knowledge area on the specification.

Which handbook chapters matter for FE Environmental?

In FE Reference Handbook 10.6, Environmental Engineering starts on page 318 and Fluid Mechanics starts on page 181. Chemistry and Biology starts on page 86, Civil Engineering on page 265, and Thermodynamics on page 143. Mathematics starts on page 36, Engineering Probability and Statistics on page 64, Ethics and Professional Practice on page 4, and Engineering Economics on page 235.

Sources

1. NCEES FE Environmental CBT exam specifications (PDF). Retrieved October 3, 2026.
2. NCEES: FE exam. Retrieved October 3, 2026.
3. NCEES FE Reference Handbook 10.6 (free PDF in MyNCEES). Retrieved October 3, 2026.