The 8 Most Tested Topics in the WR&E Exam ??

What if you could pass the Civil PE Water Resources Exam without mastering every single topic in the specs inside and out? ??

Well, you can — if you focus on the topics that get tested the most on the exam.

I reached out to two past CEA students who took and crushed that exam last year to get to know the topics that came up more often…and how they were presented. ??

If you truly master and understand only a few topics going into the PE Water Resources Exam, they should be these. ??

The 2 Must-Know Water Resources Topics to Pass ?

First of all, don’t get me wrong.

Having a good enough understanding of all the topics listed in the specifications is important (and you should absolutely study and practice all of them!). But…

Given that your score is based on the number of questions you get correct on the exam, it makes sense to get really good at the topics that get tested the most, right?

But what are they? ??

According to past CEA student, Taylor Austin…

The 2 most tested topics on the exam are Hydraulics and Hydrology. ?? ???

These two topics account for about half the Water Resources-specific questions on the exam, and these questions tend to be calculation problems (aka, doing math).

So, mastering not only all the Hydraulics and Hydrology theory but also knowing how to apply all the theory to solve questions is a MUST if you want to pass the WR&E exam.

Here’s what you need to know the most about Hydraulics. ??

While Hydraulics is a big topic, the NCEES boils it down to Closed Conduit and Open-Channel Flow…with the latter taking the cake for the most number of problems on the exam.

The most common Hydraulics concepts and equations you will need to know for the exam are:

• Conservation of energy – the energy equation (or Bernoulli's equation)

• Reynold’s number and head loss — Hazen-William's equation and Darcy-Weisbach equation

• Normal and critical flow — plus their associated equations

• Steady uniform flow — Manning’s and Chezy equations

The most common types of Hydraulics problems the NCEES throws at you are:

• Finding velocity or velocity head using the energy equation

• Sizing a pipe or determining pipe capacity using steady uniform flow equations

• Finding discharge rates for open channel flows

Now, here's what you need to know the most about Hydrology. ??

Just like Hydraulics, Hydrology is also a big topic. But for the exam, it primarily boils down to runoff analysis and hydrographs.

The most common hydrology concepts and equations that come up on the the exam are:

• Rational Formula

• NRCS Rainfall-Runoff Method — plus its associated equations

• Unit Hydrographs

• Time of Concentration

The most common types of Hydrology problems the NCEES throws at you include:

• Sizing a pipe/channel to carry stormwater runoff from a watershed area

• Determining storage for stormwater runoff, which we’ve already covered in a past article

• Interpreting unit hydrographs (e.g., determining baseflow, calculating stormwater runoff volume or flow rate from a watershed area, etc.)

• Determining time of concentration using an Intensity-Duration-Frequency (IDF) curve, which we’ve also covered in another article already

4 Secondary Topics You Need a Good Understanding of ??

While Hydraulics and Hydrology make up a huge portion of the exam, they are not the only topics you need to master.

There are other four topics that make up about the other half of the Water Resources-specific questions…and those tend to be theory problems! ??

(Do you see now why I harp on practicing theory problems as much as calculation problems…and why I created the 100 Bonus Water Resources Theory Questions? ??)

Here’s what these other four secondary topics are, according to Taylor… ??

1) Water Quality ??

Some key concepts to know about water quality include:

• Mass continuity and conservation: The equations for this on the PE Handbook are not the most straightforward to use during the exam. So, Taylor suggests using the simpler “C1Q1 + C2Q2 = C3Q3” equations for most problems.

• Biochemical Oxygen Demand: There are a lot of variables to keep track of in the equations for this. So you really need to understand what each variable means to use these equations right.?

2) Groundwater ?

Groundwater is a short section on the PE Handbook, and the main concepts that come up on the exam are:

• Darcy’s Law

• Unconfined vs Confined aquifers — plus their associated equations

• Multiple Aquifer Layers (e.g., finding equivalent hydraulic conductivity)

3) Drinking Water Treatment ??

Another big topic on the exam, and the one with the most subtopics on the specs — 10! ??

So, here are the main Drinking Water Treatment concepts tested on the exam:

• Rapid mixing and flocculation

• Hardness and Softening — specifically how to use equivalent weights when using lime-soda in these problems

• Media Filtration — specifically packed bed media filtration

• Disinfection — specifically how to read a chlorination chart and determine breakpoint chlorination

4) Wastewater Treatment ??

This one is another huge topic both on the specs and on the exam itself, and probably one that most test-takers struggle with the most.

So, here are the main Wastewater Treatment topics you need to focus on to save you some sanity. ?? ??

• Wastewater Testing — specifically BOD

• Clarifiers and Activated Sludge Processes — specifically Mixed Liquor Suspended Solids (MLSS) and Organic Loading Rate equations

• Nitrification/Denitrification — a big one tested on theory problems

• Solids Treatment, Handling, and Disposal — specifically what each variable means when using sludge weight to determine weight of solids in the sludge

• Digestion — Aerobic/Anaerobic digestion problems will likely ask you to determine the volume needed for a digestion tank

The 2 Most Common Non Water Resources Topics on the Exam ???

Now, are these six Water Resources topics all you need to study? ??

Of course not!

While the exam indeed became more discipline-specific after the April 2024 changes, it still tests you on topics outside of the Water Resources world.

And according to another CEA student, Kim Truong, there are two of them that caught her off guard because of the sheer number of problems that were asked about them.

They are Project Planning and Project Sitework.

These are two topics that were the result of a recombination of what used to be breadth topics, but they still appear on the discipline-specific exam.

(Do you see now why only studying your depth stuff is not gonna cut it…unfortunately? ??)

According to Kim, the main subtopics within Project Planning and Project Sitework that the NCEES sent her way more often were the following:

• Horizontal and Vertical Curves

• Economic Analysis

In other words…

You’ll have to make an effort to study those Transportation and Construction topics. Even if only a little bit. ??

Now It’s Your Time to Pass, Too! ??

That’s it! You now have the inside scoop on the most tested topics in the Civil PE Water Resources Exam…straight from those who’ve been in your shoes and kicked this thing in the butt. ?

Take this advice to heart, focus on mastering these topics, and you can be the next to crush this exam as well.

And if you want more tips like these, don't forget to follow us at Civil Engineering Academy !