Prepare for the NGWA Master Groundwater Contractor (MGWC) exam by covering six official skill areas: business management (30 percent), troubleshooting and diagnostics (25 percent), drilling operations (15 percent), water systems (15 percent), water quality and sustainability (10 percent), and emerging issues (5 percent), tested mostly through essays in one four-hour session. You must already hold NGWA certification in good standing in all categories except M and N, plus five years of full-time experience in well construction or pump installation. The exam runs annually at Groundwater Week, or by arrangement at NGWA with 30 days' notice; a 70 percent score passes and the fee is $75. Confirm current details with NGWA's certification coordinator before booking.
What the MGWC credential recognizes
The Master Groundwater Contractor designation is NGWA's master-level certification for water well construction and pump installation, and it has a strict eligibility gate you should confirm before studying.
The Master Groundwater Contractor (MGWC) designation recognizes proven knowledge and dedication in water well construction and pump installation. It sits above NGWA's base contractor certifications and is aimed at contractors with substantial operational or supervisory responsibility.
Eligibility is specific. You must already be certified and in good standing in every NGWA exam category except M and N, and you must have five years of full-time experience in well construction or pump installation in an operational or supervisory capacity.
NGWA also expects candidates to bring good customer service and employee relations skills on top of a solid technical operations background. If you are unsure whether your current certifications and experience qualify, contact NGWA's certification coordinator before you commit to a study schedule.
Exam format, weights, and scheduling
You will sit a revised, mostly essay-based exam in one four-hour session, scored with a 70 percent pass mark, at a $75 fee, either at Groundwater Week or by arrangement at NGWA.
NGWA describes the exam as mostly essays with some multiple-choice questions. It must be completed in one consecutive four-hour session. The page refers to a revised exam without giving a revision date, so it should not be read as announcing a new 2026 version.
A minimum score of 70 percent is required to pass. The fee is $75, which NGWA attributes to the special handling this exam requires. Formats and fees can change, so confirm both when you register.
Scheduling is flexible. The exam is offered annually at NGWA's Groundwater Week, and candidates can also test at NGWA anytime during the year after making arrangements 30 days in advance. The certification coordinator's contact details appear at the end of this guide.
NGWA publishes the skill and competency areas with percentage weights, shown below. These weights are the single best guide to how you allocate study time.
| Official skill area | Share of the exam |
|---|---|
| Business management | 30 percent |
| Troubleshooting and diagnostics | 25 percent |
| Drilling operations | 15 percent |
| Water systems | 15 percent |
| Water quality and sustainability | 10 percent |
| Emerging issues | 5 percent |
Business management: the largest testing area
Business management carries 30 percent, the largest share of the exam. Include written business problems in your preparation alongside technical topics.
The published allocation gives business management a substantial role. Use your own strengths and gaps to decide how much revision time it needs.
NGWA's job task analysis for drilling contractors gives you a concrete topic map for this area: managing financial resources and human resources, obtaining business licenses and insurance coverage, maintaining external professional relationships, complying with regulatory standards such as OSHA, DOT, and EPA rules, implementing a safety plan, and developing a marketing plan. Treat these as study areas to cover, not as a list of procedures to memorize.
A useful way to practice is a simple job costing calculation, since pricing and estimating appear in the task analysis. The exercise below is arithmetic practice; it does not describe an NGWA pricing rule or an actual exam question.
Worked exercise
A contractor quotes a customer $12,000 for a complete pump installation. The job's direct costs (labor, materials, and subcontracted work) plus an allocated share of company overhead total $10,500. Assume profit margin means profit divided by the quoted price. Calculate the job's total profit and its profit margin as a percentage.
Show answer
Total profit is $1,500 and the profit margin is 12.5 percent.
Profit is quoted price minus the total costs supplied: $12,000 − $10,500 = $1,500. Under the stated definition, margin is $1,500/$12,000 = 0.125, or 12.5 percent. This is an original arithmetic exercise, not an NGWA pricing rule or grading rubric.
Sources used: Groundwater | Master Groundwater Contractors (NGWA) — MGWC program page: eligibility, skill-area weights, format, fee, and scheduling; DACUM Research Chart for Drilling Contractors and Operators (NGWA/CETE, 2003) — Duties A–L task lists, including business activities and professional development
Drilling operations and water systems fundamentals
Drilling operations and water systems carry 15 percent each, and the core of both is being able to explain in writing how each construction method works and what each construction phase accomplishes.
As a writing exercise, explain how each method excavates and where its circulating fluid travels. The table below summarizes USGS descriptions as groundwater background.
On the construction side, NGWA's drilling task analysis maps the full arc of a well project: assessing client needs, preparing proposals and permits, drilling the borehole, installing casing, screen, and filter pack, running geophysical logs and plumbness and alignment checks, developing the completed well, and later decommissioning it. Pump installers have a parallel chart covering site assessment, pump and component selection, installation, and customer follow-up. Use both charts as coverage checklists for your notes; they describe the work of the trade, not exam questions.
One mechanism worth being able to explain precisely is well development. Its objective is to remove clay, silt, and fine-grained sand from the area next to the screen or open hole so the well will produce sediment-free water.
| Method | How it excavates |
|---|---|
| Cable tool (percussion) | Alternately raises and drops a heavy chisel-bit weight; shattered rock and water form a slurry removed with a bailer |
| Hydraulic rotary, normal circulation | Rotating drill pipe with a drag or roller bit; fluid with clay circulates down the drill pipe and up the annular space, cooling the bit and lifting cuttings |
| Hydraulic rotary, reverse circulation | Same rotary principle, but the drilling fluid moves down the annular space and up the drill pipe |
| Air rotary | Like hydraulic rotary, but uses air rather than mud as the drilling fluid |
| Bored | Earth augers turned by hand or power equipment |
| Driven | A casing equipped with a screened drive point, driven into place |
| Jetted | Excavates the hole with a high-pressure jet of water |
Sources used: Groundwater | Master Groundwater Contractors (NGWA) — MGWC program page: eligibility, skill-area weights, format, fee, and scheduling; DACUM Research Chart for Drilling Contractors and Operators (NGWA/CETE, 2003) — Duties A–L task lists, including business activities and professional development; DACUM Research Chart for Pump Installers (NGWA/CETE, 2003) — Duties A–G task lists, including troubleshooting and administrative activities; USGS Water-Supply Paper 2220, Basic Ground-Water Hydrology (1983) — Selected descriptive passages: well construction methods, well development, specific capacity
Reading a test with specific capacity
Specific capacity is pumping rate divided by drawdown measured at the same time during a test.
Keep the rate, drawdown and measurement time together when reading a test record. The specific-capacity definition requires rate and drawdown from the same test moment.
Keep the ratio's limits in view as well. Because specific capacity describes one moment at one rate, it lets you compare drawdown behavior at tested rates, but it does not by itself establish what a well can sustainably yield over the long term. The exercise below applies the definition twice.
Worked exercise
During a constant-rate test, a well is pumped at 150 gallons per minute, and at the 60-minute reading the drawdown measures 15 feet. A neighboring test well is pumped at 90 gallons per minute and, at the same 60-minute elapsed time, shows 6 feet of drawdown. Compute the specific capacity of each well and state which delivers more yield per foot of drawdown.
Show answer
First well: 10 gallons per minute per foot. Second well: 15 gallons per minute per foot. The second well delivers more yield per foot of drawdown.
Divide each pumping rate by the drawdown read at the same elapsed time: 150 ÷ 15 = 10 gpm/ft, and 90 ÷ 6 = 15 gpm/ft. The comparison is valid because both readings were taken at the same 60-minute mark. Each figure still describes only the tested moment and rate, so neither number alone proves long-term sustainable yield.
Troubleshooting and diagnostics at 25 percent
Troubleshooting and diagnostics carry 25 percent. Practising written explanations of evidence and conclusions can help you prepare for the mostly essay format.
The pump chart lists observing the system, checking controls, electrical parameters, pump operation and water-source parameters. These identify subjects to study; they do not establish one diagnostic sequence or an official essay marking scheme.
Because most of the exam is essays, practice writing the reasoning, not just the conclusion. State what you would check first, what each reading would tell you, and what would rule a candidate cause out. Treat the task chart as a map of what experienced practitioners examine, then build your own written diagnostic sequences for common complaints such as loss of pressure or short cycling.
Sources used: Groundwater | Master Groundwater Contractors (NGWA) — MGWC program page: eligibility, skill-area weights, format, fee, and scheduling; DACUM Research Chart for Pump Installers (NGWA/CETE, 2003) — Duties A–G task lists, including troubleshooting and administrative activities
Water quality, sustainability, and emerging issues
Water quality and sustainability carry 10 percent and emerging issues another 5 percent; the task analyses name the relevant work, and NGWA should confirm any current subtopics.
The task analyses name the relevant work in these areas: sampling water quality, monitoring well performance and discharge water, disinfecting completed wells, managing development chemicals, and managing development of the screened production zone. These make a practical coverage checklist for your notes.
Emerging issues is the area where NGWA's own current objectives matter most, because the topics change faster than any study guide. The detailed subtopic list for the revised exam was not available in the materials reviewed for this guide, so ask the certification coordinator what to emphasize in the current version.
Sources used: Groundwater | Master Groundwater Contractors (NGWA) — MGWC program page: eligibility, skill-area weights, format, fee, and scheduling; DACUM Research Chart for Drilling Contractors and Operators (NGWA/CETE, 2003) — Duties A–L task lists, including business activities and professional development; USGS Water-Supply Paper 2220, Basic Ground-Water Hydrology (1983) — Selected descriptive passages: well construction methods, well development, specific capacity
How to prepare and what to do next
Allocate study time by the official weights, practice writing full timed answers, and confirm every administrative detail with NGWA before booking.
Use the official weights and your own knowledge gaps to allocate revision time. Include business management and troubleshooting alongside construction topics; neither area can be covered by drilling-method notes alone.
Since the bulk of the exam is essays, practice writing complete answers. Take one topic per sitting — a job estimate, a pump complaint, a method choice — and write a timed, structured response. Grade it for whether a reader could follow your reasoning, not just whether the conclusion is right.
For anything administrative — the current outline, eligibility confirmation, fees, or scheduling — contact NGWA's certification coordinator at certification@ngwa.org or call (800) 551-7379, or (614) 898-7791 from outside the United States.
- Confirm your eligibility, including existing NGWA certifications and your five-year experience record, with the certification coordinator.
- Weight study time toward business management (30 percent) and troubleshooting and diagnostics (25 percent).
- Practice essay-style answers under time pressure, one skill area at a time.
- Work the free practice questions after content review, tracing each miss back to a skill area.
Sources used: Groundwater | Master Groundwater Contractors (NGWA) — MGWC program page: eligibility, skill-area weights, format, fee, and scheduling; DACUM Research Chart for Drilling Contractors and Operators (NGWA/CETE, 2003) — Duties A–L task lists, including business activities and professional development; DACUM Research Chart for Pump Installers (NGWA/CETE, 2003) — Duties A–G task lists, including troubleshooting and administrative activities
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