1.2 Reference Handbook and Units
Key Takeaways
- For active pre-April-2027 WRE exams, the supplied references are the NCEES PE Civil Reference Handbook plus TSS Wastewater Facilities 2014 and TSS Water Works 2018.
- Personal notes, printed handbooks, outside PDFs, and candidate-supplied design standards are not allowed in the exam room.
- NCEES states that standards are supplied as searchable electronic PDFs, with standards opened and searched by chapter during the exam.
- The WRE specification uses both SI and U.S. Customary units, so unit setup is a core scoring skill rather than a final cleanup step.
- Candidates testing in April 2027 or later must recheck the NCEES standards list because the posted future WRE file changes supplied design standards.
Treat References as Test Tools
The PE Civil WRE exam is closed book with electronic references. For the active pre-April-2027 WRE specification, NCEES supplies the PE Civil Reference Handbook and two listed design standards: TSS Wastewater Facilities 2014 and TSS Water Works 2018. Personal copies, printed binders, personal notes, and outside PDFs are not allowed in the testing room.
That reference policy changes how you should study. Your goal is not to memorize every equation in hydrology, pipe flow, open-channel flow, treatment, groundwater, or sitework. Your goal is to know which reference family controls the problem, how to navigate to it quickly, and how to verify that the variables and units match the item.
| Supplied item before April 2027 | Best use | Practice habit |
|---|---|---|
| PE Civil Reference Handbook | Equations, constants, definitions, charts, unit relationships | Use the current MyNCEES copy during every timed set. |
| TSS Wastewater Facilities 2014 | Wastewater design criteria and treatment references | Practice locating criteria by treatment unit, not by memory alone. |
| TSS Water Works 2018 | Drinking-water works criteria and distribution/treatment context | Search by facility type, demand term, and process name. |
How Electronic Search Changes the Work
The handbook and standards are searchable electronic PDFs, but they are not a private laptop setup. NCEES describes standards as individual chapters, with only one chapter open and searchable at a time so the software performs efficiently. During preparation, avoid building habits around browser tabs, printed sticky notes, or a giant personal equation sheet.
A useful reference drill is to solve a problem twice. First, solve it normally. Second, write down the exact reference path you used: topic, search term, equation label or table, and the unit trap. Over time, this creates memory for navigation without depending on prohibited materials.
Units Are a First-Pass Decision
The WRE specification uses both the International System of Units (SI) and U.S. Customary System (USCS). Many misses happen before the engineering begins: gallons per minute mixed with cubic feet per second, million gallons per day converted late, milligrams per liter treated as mass rather than concentration, or head and pressure placed in the same equation without conversion.
Use this unit process on every quantitative item:
- Circle or restate the target unit before opening the handbook.
- Convert flow, area, and time units before substituting into an equation.
- Keep concentration-load problems dimensional from start to finish.
- Use the handbook conversion factor or constant that matches the requested unit system.
- Check whether the answer magnitude fits the facility or watershed scale.
High-frequency WRE unit contexts include MGD, gpm, cfs, acre-feet, ft of head, psi, mg/L, lb/day, square feet, acres, and cubic yards. The local practice and flashcard sets emphasize the same traps: flow versus load, peak rate versus runoff volume, energy grade line versus hydraulic grade line, and open-channel versus pressurized-flow assumptions.
Standard-Year Discipline
When a question references a design standard, NCEES scores based on the standards and revision years listed in the exam specification. For exams before April 2027, that means the active WRE list, including TSS Water Works 2018. The posted April 2027 WRE file changes the design-standard environment, so candidates testing after the transition should not assume the same reference list or revision years.
For a PE Civil WRE exam taken before the April 2027 transition, which reference set should a candidate practice with?
A practice problem gives flow in gpm, pipe length in feet, concentration in mg/L, and asks for a load in lb/day. What is the best first move?