Exam N is NGWA's specialty exam in well servicing and maintenance: 50 multiple-choice questions, one hour, closed book, with a 70 percent minimum passing score. It is scheduled year-round through PSI. To prepare, review the NGWA Exam Preparation Success Guide, study the texts NGWA recommends for all exams, and map your reading to the DACUM task charts for well rehabilitation, development, pump troubleshooting, sampling, and records. Specialty exam content beyond the single listed domain is not published, so confirm current details with NGWA and PSI.
What Exam N is and how it is scored
Exam N: Well Servicing and Maintenance is a specialty exam in NGWA's contractor certification program. It contains 50 questions, allows one hour, and requires a score of 70 percent or better.
The National Ground Water Association runs a voluntary certification program for groundwater contractors, started in 1970 and designed by practicing contractors. Several state agencies use the same exams in their own licensing programs, which makes the credentials useful beyond NGWA membership.
Exam N sits in NGWA's specialty exam category, alongside the drilling and pump/water systems categories rather than inside either one. The PSI candidate information bulletin states that all NGWA examinations are closed book and lists Exam N at 50 questions with a 70 percent minimum passing score and one hour allowed.
Unlike some other NGWA exams, Exam N has no published topic breakdown. The content table shows a single domain, Well Servicing and Maintenance, carrying all 50 questions. Plan your coverage around the task charts and recommended texts described below instead of hunting for official sub-weights.
| Fact | Value |
|---|---|
| Questions | 50 |
| Time allowed | 1 hour |
| Minimum passing score | 70 percent |
| Format | Closed book |
| Administered by | PSI Services |
Official sources used: Groundwater | NGWA Certification exams — Certification exams page: exam categories, preparation, fees, scheduling; Groundwater | NGWA Certification for contractors — Program overview and eligibility requirements; PSI NGWA candidate information bulletin — Cover September 20, 2022; content pages 5-7: exam format tables
How Exam N fits the CWD and CPI designations
The CWD and CPI designations each require a general exam plus one specialized exam from their own category, passed within 12 months at 70 percent or better. Exam N is listed separately, in the specialty category.
To earn the Certified Well Driller designation, you must pass the general drilling exam and at least one other specialized drilling exam. To earn the Certified Pump Installer designation, you must pass the water systems general exam and at least one other specialized pump/water systems exam. NGWA requires both qualifying exams to be passed within one 12-month period with scores of 70 percent or better on each.
Exam N appears under a separate specialty exam category, not under the drilling or pump categories that supply those required pairs. The published requirements do not name specialty exams in the qualifying combinations, so if you intend Exam N to count toward a designation, confirm the current rule with NGWA's certification coordinator before you schedule.
Sitting an exam and earning the credential are separate steps. The PSI bulletin states that no NGWA approval is needed to sit an exam; eligibility and the certification application are handled apart from scheduling. NGWA's published eligibility asks that you be at least 20 years old, have at least 24 consecutive months of full-time drilling or pump installation experience, and submit written references from two professional contacts outside your current company, plus an agreement form and a current-year affidavit. Application materials must arrive within 12 months of your qualifying exam session.
Official sources used: Groundwater | NGWA Certification exams — Certification exams page: exam categories, preparation, fees, scheduling; Groundwater | NGWA Certification for contractors — Program overview and eligibility requirements; PSI NGWA candidate information bulletin — Cover September 20, 2022; content pages 5-7: exam format tables
Scheduling, test centers, and your score report
PSI administers the exams online year-round at more than 400 test centers nationwide. Scores are issued immediately, so collect your score report before leaving the test center.
You schedule through PSI's test-taker website or by calling PSI at (855) 579-4642. The exam can be taken year-round, and NGWA notes the program requires no special computer skills. All testing centers are ADA compliant.
If you need special accommodations, contact NGWA at (800) 551-7379, or (614) 898-7791 from outside the United States, or email certification@ngwa.org. NGWA records your information and sends approval to PSI, and someone from PSI then contacts you to complete registration.
Your score prints immediately after you finish, so collect it at the test center before leaving. NGWA can reissue scores for a fee if you lose the report, but scores are never given over the phone. Because the candidate bulletin on file is dated 2022, verify current scheduling details on PSI's site before booking.
Official sources used: Groundwater | NGWA Certification exams — Certification exams page: exam categories, preparation, fees, scheduling; PSI NGWA candidate information bulletin — Cover September 20, 2022; content pages 5-7: exam format tables
Mapping the content: the task charts behind servicing work
The official outline names a single 50-item domain. NGWA's DACUM job task analysis charts give you a defensible study map: well rehabilitation and development tasks from the drilling chart, and troubleshooting, sampling, and records tasks from the pump installers chart.
DACUM stands for Developing a Curriculum. NGWA built these charts with panels of working water well professionals to analyze the major duties and tasks of each trade. They describe what practitioners do, which makes them a reasonable map of what a servicing exam can draw on, but they are not the official Exam N blueprint and they are not procedure manuals.
The drilling contractors chart includes duties to rehabilitate wells, with tasks such as determining the existing well construction and water chemistry, videologging the well, and implementing a treatment plan, and to develop wells, with tasks including agitating the production zone, monitoring sediment removal and well performance, sampling water quality, disinfecting the well, and installing a sanitary cover. The pump installers chart includes troubleshooting an existing pump system, from observing the system and controls through checking electrical parameters such as volts, amps, and resistance and pump operation such as pressure, cycle time, and flow, along with processing water samples and maintaining customer records.
A workable study loop: pick one duty from a chart, list its tasks, and for each task ask what you would need to know to perform it correctly. Where your answer depends on a procedure, go to the recommended texts rather than the chart, because the chart only names the task. NGWA also publishes the Exam Preparation Success Guide as an overview of how and what to study.
- Rehabilitate wells: well construction, water chemistry, videolog, treatment plan
- Develop wells: production-zone agitation, sediment and performance monitoring, water sampling, disinfection, sanitary cover
- Troubleshoot pump systems: observe system and controls, check electrical parameters, check pump operation
- Records and customer tasks: water sample processing, invoices, warranty information, customer follow-up
Official sources used: Groundwater | NGWA Certification exams — Certification exams page: exam categories, preparation, fees, scheduling; PSI NGWA candidate information bulletin — Cover September 20, 2022; content pages 5-7: exam format tables; Drilling contractors and operators (DACUM Research Chart) — Duties F (Rehabilitate Wells) and G (Develop Wells); Pump installers (DACUM Research Chart) — Duties F (Troubleshoot Existing Pump System) and G (Administrative Activities)
Recommended study materials
NGWA recommends the Professional Designations Information and Study Guide and Groundwater & Wells, third edition, for all exams. Check with NGWA before buying anything else specifically for Exam N.
Two titles on NGWA's recommended list are marked for all exams: the Professional Designations Information and Study Guide, which covers study materials for every exam in the program, and Groundwater & Wells, third edition. The Professional Designations guide is available through the NGWA online store.
Other recommended texts are scoped to specific exam groups. The Water Systems Handbook, 13th edition, is listed for the water systems exams and the general drilling exam, and the safety manuals are listed for drilling and general exams, so do not assume they are assigned reading for Exam N. The page does not itemize a dedicated Exam N reading list beyond the all-exams titles.
NGWA University's online training courses target the General Drilling and Water Systems exams, so treat them as background support rather than Exam N preparation. For questions about other study materials, NGWA lists customer service at (800) 551-7379 or (614) 898-7791.
Official sources used: Groundwater | NGWA Certification exams — Certification exams page: exam categories, preparation, fees, scheduling
Fundamentals worth practicing: specific capacity
Well development aims to remove clay, silt, and fine sand near the screen or open hole so the well yields sediment-free water. Specific capacity, the pumping rate divided by drawdown at the same time, is a measurement you can practice on paper.
The USGS reference Basic Ground-Water Hydrology gives two fundamentals that recur in servicing study. First, well development is the phase after construction that removes clay, silt, and fine-grained sand from beside the screen or open hole so the well produces sediment-free water. Second, specific capacity is the yield per unit of drawdown, found by dividing the pumping rate at any time during a test by the drawdown at that same time.
Specific capacity describes the flow-to-drawdown ratio for the observations supplied. Comparable test conditions help interpretation, but the ratio alone does not identify a cause, establish sustainable yield or select a replacement pump.
In the original exercise below, each rate and drawdown pair is measured at four hours. Calculate both ratios, then describe only the numerical change supported by those observations.
Practice exercise
A production well was tested in 2023: after exactly 4 hours of pumping at a steady 60 gpm, drawdown measured 10 ft. The identical test was repeated in 2025, also 4 hours: 60 gpm with drawdown of 15 ft. Specific capacity equals pumping rate divided by drawdown at the same elapsed time. Calculate specific capacity for each test, state the change, and explain what the comparison does and does not tell you.
Show answer
2023: 60/10 = 6 gpm/ft. 2025: 60/15 = 4 gpm/ft. The measured ratio fell by one third. These observations support further investigation of the change, but do not identify its cause or justify a particular repair, sustainable-yield figure or pump choice.
Within each test, the rate and drawdown are measured at the same time, as required for Q/s. Both tests also use the same stated pumping rate and elapsed time. The second test records more drawdown for that rate. Other information would be needed to explain why; a ratio alone is not a diagnosis.
Official sources used: USGS Water-Supply Paper 2220, Basic Ground-Water Hydrology — Selected fundamentals: well development and specific capacity definitions
Next steps before you book
Review the Exam Preparation Success Guide, get the all-exams study guide, work the task charts into a study plan, and confirm current requirements with NGWA and PSI, since the bulletin on file dates to 2022.
A practical sequence: first read the Exam Preparation Success Guide for NGWA's own study overview. Then obtain the Professional Designations Information and Study Guide and Groundwater & Wells, third edition, the two texts NGWA lists for all exams. Use the DACUM charts to turn your field experience into a task-by-task self-check, flagging the servicing tasks you could not yet explain from the recommended texts.
Confirm the administrative picture before scheduling: whether Exam N counts toward any designation you are pursuing, the current fee and scheduling process, and any state licensing requirements that apply where you work. NGWA's certification staff can answer program questions at certification@ngwa.org, and state agencies set their own licensing rules independently of NGWA certification.
Finally, remember the boundaries of paper preparation. Task charts and reference texts describe what competent practitioners do; they do not substitute for supervised field training. Use this guide to organize knowledge, not to replace hands-on competence.
- Read the NGWA Exam Preparation Success Guide
- Buy the Professional Designations Information and Study Guide and Groundwater & Wells, third edition
- Self-check against the DACUM duties for rehabilitation, development, troubleshooting, sampling, and records
- Verify current exam rules with NGWA and PSI, and check your state's licensing requirements
Official sources used: Groundwater | NGWA Certification exams — Certification exams page: exam categories, preparation, fees, scheduling; Groundwater | NGWA Certification for contractors — Program overview and eligibility requirements; PSI NGWA candidate information bulletin — Cover September 20, 2022; content pages 5-7: exam format tables; Drilling contractors and operators (DACUM Research Chart) — Duties F (Rehabilitate Wells) and G (Develop Wells); Pump installers (DACUM Research Chart) — Duties F (Troubleshoot Existing Pump System) and G (Administrative Activities)
Official sources used
Facts checked against official sources: