- Why Six Domains Are Only Half the Credential
- The Six Domains at a Glance
- Domain 2: Construct Water Well (The Heavyweight)
- Domains 1 and 6: Mobilize and Demobilize
- Domains 3, 4, and 5: Rehabilitate, Develop, Decommission
- Choosing Your Drilling Specialty Exam
- Exam Format, Fees, and Test-Day Rules
- Category-Mapped Practice Questions
- Sequencing Your Preparation by Domain
- Voluntary NGWA Certification vs. State Licensing
- Keeping the Credential Active
- Frequently Asked Questions
- CWD requires General Drilling plus at least one drilling-method specialty exam, each passed at 70% or higher within 12 months.
- The six domains are General Drilling objectives only; they do not blueprint your specialty exam.
- Published item counts are 10, 16, 5, 11, 3, and 5 across the six domains.
- Construct Water Well carries the most items, so it deserves the largest share of your study hours.
Why Six Domains Are Only Half the Credential
The most common misreading of the Certified Well Driller credential is treating the six content areas as the whole exam. They are not. The six domains below are the formal objectives for the General Drilling examination offered through the National Ground Water Association (NGWA) and administered by PSI Services. Passing General Drilling alone does not confer CWD.
The credential requires two things passed within the same 12-month period, each at 70% or higher: General Drilling and at least one drilling-method specialty exam. That means your preparation has two tracks. This guide maps the first track in detail and helps you think through the second. For the full eligibility picture, see our CWD requirements breakdown.
The Six Domains at a Glance
The General Drilling outline publishes item counts for each domain, not percentage weights. We have not converted these into percentages because the published material does not do so. Here is how the 50 General Drilling questions are allocated by domain:
| Domain | Published Item Allocation | Where It Sits in the Job |
|---|---|---|
| 1. Mobilize for the Site | 10 | Before drilling begins |
| 2. Construct Water Well | 16 | The core drilling and completion work |
| 3. Rehabilitate Wells | 5 | Restoring existing wells |
| 4. Develop Wells | 11 | Post-construction performance work |
| 5. Decommission Wells | 3 | Permanent closure |
| 6. Demobilize the Site | 5 | Cleanup and departure |
The allocations add up to 50, matching the General Drilling format of 50 multiple-choice questions in 60 minutes. Because 16 items sit in a single domain, a weak performance in Construct Water Well is very hard to offset elsewhere. For a candid look at how this affects difficulty, read How Hard Is the CWD Exam?
Domain 2: Construct Water Well (The Heavyweight)
With 16 items, Construct Water Well is the largest single block on the General Drilling exam. It covers the work that most candidates do every day, which is exactly why it can feel deceptively easy. The exam tests whether your field habits line up with accepted practice and the reasoning behind it, not whether you can simply get a hole drilled.
Domain 2: Construct Water Well
Expect scenario-style multiple-choice questions that ask you to choose the correct action, material, or sequence when building a well.
- Drilling method selection as it relates to formation conditions
- Borehole stability and fluid or air management during drilling
- Casing selection, installation, and the logic behind each choice
- Annular space treatment, including grouting and sealing concepts
- Screen and filter pack decisions where the formation calls for them
- Sanitary protection of the well during and after construction
Because the exam is closed-book and computer-based, you cannot rely on a reference chart. A nonprinting, nonprogrammable calculator without an alphabetical keypad is permitted, so practice the arithmetic you are likely to need by hand and with that type of calculator. Volume, depth, and annular-space calculations reward repetition more than memorization.
Domains 1 and 6: Mobilize and Demobilize
These two domains bookend every job, together accounting for 15 of the 50 items. Candidates with strong drilling experience often skim them. That is a mistake, because these are points where regulations, safety, and documentation matter as much as technical skill.
Domain 1: Mobilize for the Site (10 items)
Domain 1: Mobilize for the Site
Preparation before the rig turns. Questions here test planning, awareness, and compliance.
- Site assessment and locating the well relative to potential contamination sources
- Awareness of underground and overhead utilities before ground is broken
- Permitting and notification responsibilities
- Equipment and materials readiness
- Site safety planning and worker protection
Domain 6: Demobilize the Site (5 items)
Domain 6: Demobilize the Site
The finishing work that protects the owner, the aquifer, and your reputation.
- Handling and disposal of cuttings and drilling fluids
- Site restoration and wellhead protection
- Record keeping and documentation for the owner and regulators
- Equipment cleaning to avoid cross-contamination between sites
Think of these domains as the "professional judgment" portion of the exam. A candidate who drills well but cuts corners on planning and cleanup will struggle here. If you are weighing whether the investment of time is worthwhile, see Is the CWD Certification Worth It?
Domains 3, 4, and 5: Rehabilitate, Develop, Decommission
These three domains cover what happens to a well after the initial drilling. Together they account for 19 items, and the middle one, Develop Wells, is the second-largest block on the exam at 11 items.
Domain 4: Develop Wells (11 items)
Domain 4: Develop Wells
Development turns a constructed borehole into a productive, clean-producing well. Many candidates underestimate this domain because it sits after "the real drilling."
- Purpose of development and how it relates to the formation and filter pack
- Common development methods and when each is appropriate
- Removing fines, drilling-fluid residue, and sediment
- Testing and evaluating well performance after development
- Recognizing when development is complete versus when more work is needed
Domain 3: Rehabilitate Wells (5 items)
Domain 3: Rehabilitate Wells
Restoring capacity or water quality in an existing well.
- Diagnosing why a well has lost performance
- Matching a rehabilitation approach to the problem
- Safety and environmental considerations when treating a well
- Verifying that rehabilitation worked
Domain 5: Decommission Wells (3 items)
Domain 5: Decommission Wells
The smallest domain, but the concepts are highly testable because correct closure is a protective, regulated practice.
- Why abandoned wells are a contamination pathway
- Preparing a well for sealing
- Appropriate sealing materials and placement concepts
- Documentation of the closure
Key Takeaway
Do not skip Decommission Wells just because it has only 3 items. In a 50-question exam where the pass line is 70%, every point matters. Cheap, learnable domains are where careful candidates protect their margin.
Choosing Your Drilling Specialty Exam
Once you understand General Drilling, you need a specialty to complete the pathway. Drilling specialty examinations normally have 50 questions. The exception is Exam M, Augering and monitoring, which has 75 questions. That is a meaningful difference in length and endurance, so factor it into your choice.
Pick your specialty based on the work you actually perform. The exam assumes hands-on familiarity with the method, and the questions reward practical judgment. A few decision points to weigh:
- Match your daily work. Choose the method where you have the deepest field experience, since you will recall real situations more easily under time pressure.
- Consider your market. Employers and clients in your region may care more about certain methods than others. Our CWD jobs overview discusses who tends to hire certified drillers.
- Account for length. If you choose Exam M, expect 75 questions rather than the usual 50, and plan your stamina accordingly.
- Confirm the scope. The six domains in this article do not describe specialty content, so check NGWA's current materials for the specialty you select.
Exam Format, Fees, and Test-Day Rules
PSI Services administers these closed-book, computer-based examinations at proctored centers. Knowing the mechanics in advance removes avoidable stress.
| Item | What the Published Facts Say |
|---|---|
| General Drilling format | 50 multiple-choice questions in 60 minutes |
| Specialty exam length | Normally 50 questions; Exam M (Augering and monitoring) has 75 |
| Passing standard | At least 70% on each exam |
| Exam fee | $75 per exam, for members and nonmembers |
| Minimum two-exam cost | At least $150 for two first-attempt exams |
| Calculator | Nonprinting, nonprogrammable, no alphabetical keypad |
| Scratch paper | Supplied and collected at the end |
On eligibility, candidates must be age 20 or older and have 24 consecutive months of full-time drilling or pump-installation experience. You also need two written professional references unaffiliated with your current employer, the required agreement, and a current-year affidavit. Application materials must arrive within 12 months of the qualifying examination session. For scheduling, see CWD exam dates and deadlines, and for scoring details, read about the CWD passing score.
Category-Mapped Practice Questions
The questions below are original illustrations written to show the style of reasoning each domain demands. They are not actual exam items. For a larger bank mapped to all six domains, use the CWD practice test.
Domain 1 Sample: Mobilize for the Site
A drilling crew arrives at a new site. Which action should happen before the rig is positioned over the proposed location?
- A. Begin drilling a pilot hole to test the ground
- B. Confirm utility locations and verify the proposed well site is appropriately separated from contamination sources
- C. Mix drilling fluid in advance
- D. Unload all casing at the borehole
Answer: B. Verifying utilities and separation from contamination sources is a planning step that must precede any ground disturbance. Starting to drill first, or staging materials, does not address the safety and protection issues that mobilization planning is meant to resolve.
Domain 2 Sample: Construct Water Well
Why is the annular space around a well casing typically sealed with an appropriate grouting material?
- A. To make the casing easier to remove later
- B. To increase the diameter of the borehole
- C. To prevent surface water and contaminants from migrating down the outside of the casing
- D. To reduce the cost of casing
Answer: C. The seal exists to block a vertical pathway for contamination along the casing. The other options describe outcomes that grouting is not designed to achieve.
Domain 4 Sample: Develop Wells
What is the primary goal of well development after construction?
- A. To permanently seal the borehole
- B. To remove fine material and drilling residue so the well can produce clean water efficiently
- C. To reduce the casing diameter
- D. To prepare the site for demobilization paperwork
Answer: B. Development improves hydraulic connection between the formation and the well and clears material left by drilling. It is a performance step, not a sealing or administrative one.
Domain 5 Sample: Decommission Wells
Why should an unused well be properly decommissioned rather than simply left in place?
- A. An open or deteriorating well can serve as a pathway for contaminants to reach groundwater
- B. It improves the aesthetics of the property only
- C. It increases the well's pumping capacity
- D. It is required only for new wells
Answer: A. Abandoned wells can funnel surface contamination into an aquifer, which is the central reason closure practices exist.
Sequencing Your Preparation by Domain
Rather than a generic schedule, let the domain allocations drive your calendar. The largest blocks get the earliest and longest attention, and the small domains get compact, high-efficiency review. This is one possible arrangement; adjust it to your own gaps.
Construct Water Well
- Cover the 16-item domain first, since it affects your score most
- Practice the calculations with a permitted calculator
- Note which sub-topics you miss repeatedly
Develop Wells and Mobilize
- Work through the 11-item and 10-item domains
- Connect planning decisions to later construction outcomes
Rehabilitate, Decommission, Demobilize
- Cover the three smaller domains (5, 3, and 5 items)
- Take a full timed practice set of 50 questions in 60 minutes
Specialty Exam
- Shift to your chosen drilling-method specialty
- Use the NGWA General Drilling Exam Study Guide as supplemental reference for the General Drilling headings, remembering it does not cover specialties completely
For a fuller framework and a one-page memory aid, pair this with the CWD study guide and the CWD cheat sheet.
Voluntary NGWA Certification vs. State Licensing
Certified Well Driller is a voluntary credential from NGWA. It is not the same thing as a state license, and holding one does not substitute for the other. Many jurisdictions regulate who may drill wells, and those rules vary. The NGWA renewal requirements specifically call for compliance with licensing requirements, so treat licensing as a separate obligation that you manage alongside certification.
Practically, this means you should check your own state's or province's requirements independently and not assume CWD satisfies them. For the broader meaning of the credential, see What Is CWD Certification? and, if you are still comparing acronyms, What Does CWD Stand For? to confirm you are researching the right credential.
Keeping the Credential Active
Renewal is annual. It requires seven continuing education points (CEPs), an affidavit, applicable fees, and compliance with licensing requirements. The stated renewal due date is December 31.
The currently linked 2027 renewal form lists $50 for members and $150 for nonmembers. These are renewal fees and should not be confused with the $75 exam fee.
For the earnings side of the equation, review the CWD salary guide to see how credentialing fits into your career picture. No aggregate pass rate has been verified for this credential, so treat any claimed figure with caution; our CWD pass rate article explains what the data can and cannot tell you. Note that 70% is the required exam score, not a pass rate.
Frequently Asked Questions
No. The six domains are the formal objectives for the General Drilling exam only. CWD also requires at least one drilling-method specialty exam, passed within the same 12-month period, and the specialty has its own content scope.
Construct Water Well, with 16 of the 50 General Drilling items. Develop Wells follows with 11, then Mobilize for the Site with 10. These are item counts, not published percentage weights.
General Drilling has 50 multiple-choice questions in 60 minutes. Drilling specialty examinations normally have 50 questions, except Exam M (Augering and monitoring), which has 75.
You need at least 70% on each required exam. Both General Drilling and your chosen specialty must meet that standard within the same 12-month period to earn CWD.
The published fee is $75 per exam for members and nonmembers, so two first-attempt exams cost at least $150. That is not an all-in budget; nonmembers may also face a separate certification-application fee whose amount is not published in the candidate bulletin.
Ready to test where you stand against each domain? Start with a free set of questions on the CWD Exam Prep practice test site and use your results to decide where your first study week should go.