Mississippi Irrigation Systems Exam: What You Need to Know to Pass in 2026
You've put in the field work. Now you need the paper to back it up. The Mississippi irrigation systems exam is what stands between you and a legal specialty classification with the Mississippi State Board of Contractors — the credential that lets you bid, contract, and perform irrigation work on both commercial and residential jobs. This article covers everything: the exam format, what's on it, sample questions, study materials, and the answers to the questions most candidates have before test day. Let's get into it.
Mississippi Irrigation Systems Exam Overview
The Mississippi irrigation contractor license test is administered by PSI and consists of 40 scored questions. You have 120 minutes to finish. To pass, you need at least a 70% — that's 28 correct answers out of 40.
Your score displays on screen the moment you submit. No waiting for a letter in the mail.
The exam is open book, but only one reference is allowed in the testing center: Simplified Irrigation Design, 2nd Edition (1995) by Pete Melby. You must bring your own copy. You can highlight and tab it — more on that below — but no loose papers, no additional notes, and no temporary tabs like Post-Its when you sit down.
Before you can schedule with PSI, the Mississippi Contractor Licensing Board must declare you eligible. Once they do, PSI will be notified and you can register online at the exam registration page (available 24 hours a day) or by calling PSI at (855) 557-0619. The exam fee is $120, and it is non-refundable and non-transferable whether you're taking it for the first time or retaking it.
Topics Covered on the Mississippi Irrigation PSI Exam
Here's the breakdown by topic area and the number of questions each carries on the real exam:
Piping and Valves — 14 exam items
This is the heaviest-weighted section by a wide margin. Expect questions on PVC pipe classifications (Schedule 40, Class 160, Class 200, Class 315), pressure ratings, friction loss calculations from charts, water velocity limits, surge pressure and water hammer, and backflow prevention devices. Know your fittings cold.
Layout, Plans and Specifications — 10 exam items
The second-largest section. You'll need to know how to divide a site into zones based on plant water needs, soil type, and slope. Head selection and placement, square vs. triangular spacing, precipitation rate calculations, and drip system layout with emitter placement are all fair game.
Sprinkler Heads — 6 exam items
Fixed spray vs. rotary, arc patterns, head-to-head coverage, spacing methods, and wind-adjusted spacing as a percentage of throw diameter. Triangular vs. square spacing comes up here too — know the difference and when to use each.
Controls and Wiring — 6 exam items
Controller types (electromechanical, solid-state, hybrid), programming features, pump and master valve wiring integration, and electrical basics — volts, amps, watts, voltage drop. Also includes control wire and common wire sizing from charts.
Excavation, Compaction and Grading — 2 exam items
Trench depth and width requirements, backfill and compaction specs, overexcavation for rock, pipe drainage slope for freeze protection, and minimum cover depths for mainlines, laterals, and sleeved crossings under pavement.
Pumps — 2 exam items
Horizontal centrifugal vs. vertical turbine pumps, how centrifugal pumps generate pressure, selection criteria, series vs. parallel configurations, and booster pumps for low-pressure situations.
Spend the most time on Piping and Valves, then Layout — together they account for 24 of your 40 questions.
Sample Questions from the MS Irrigation Systems Practice Exam
These are the kinds of questions you'll face. Work through them — but we're not giving you the answers here. Take the free practice exam if you want to test yourself.
Question 1 — Piping and Valves
You are assembling a PVC irrigation lateral line and need to connect pipe sections at two different trench depths — a 2-ft deep section under a driveway and a 12-in deep section in a lawn area. Which PVC fitting is used to make this solvent-cemented directional change?
- A) 90° slip elbow
- B) Flexible riser
- C) Barbed male adapter
- D) Reducing tee
Question 2 — Controls and Wiring
A solid-state irrigation controller will retain its program via battery during a power outage for what duration?
- A) 24 to 48 hours
- B) 12 to 24 hours
- C) 1 to 3 hours
- D) 3 to 9 hours
Question 3 — Piping and Valves
You are designing an irrigation system and considering a reducing 90° threaded elbow. On this fitting, which end is the larger diameter?
- A) The threaded (FPT) end
- B) Both ends are equal
- C) The slip end
- D) It varies by manufacturer
Question 4 — Pumps
You are designing an irrigation system where different circuits require varying flow rates but the same operating pressure. How should the pumps be arranged?
- A) In parallel
- B) As jockey pumps
- C) In series
- D) As multistage units
Question 5 — Layout, Plans and Specifications
You are designing an irrigation system for a large commercial turf area and considering triangular versus square head spacing. In a site with 4-mph prevailing winds, what percentage of the sprinkler throw diameter is the recommended triangular head spacing?
- A) 55%
- B) 60%
- C) 50%
- D) 45%
Know which one you'd pick on each? Head over to our free practice exam and find out if you're right.
What Types of Questions to Expect
Here's a topic-by-topic look at what our practice question bank covers — and what skills the real exam actually tests:
Piping and Valves: Expect calculation problems — friction loss from charts, surge pressure math, water velocity checks. You'll also get scenario questions on backflow preventer selection and fitting identification, like the sample questions above.
Layout, Plans and Specifications: Site-reading problems that ask you to assign zones, calculate precipitation rates, and place heads correctly for given soil and slope conditions. Drip system layout questions test emitter spacing logic.
Sprinkler Heads: Pattern recognition, spacing method comparisons, and wind-adjustment calculations. Know your percentages for triangular vs. square spacing under different wind conditions.
Controls and Wiring: Wiring diagrams, programming scenarios, and electrical calculations including voltage drop. Controller type identification questions are straightforward if you know the definitions.
Excavation, Compaction and Grading: Depth and cover requirements, backfill specs, and drainage slope problems. Two questions on the real exam — but they're specific enough that you want to have the numbers memorized.
Pumps: Series vs. parallel pump configurations, impeller-based pressure generation, and pump selection based on flow rate and pressure requirements.
Total practice questions available: 182, covering every topic on the exam.
Study Materials for the Mississippi Irrigation Systems Exam
One book is required. A few extras will make your prep faster.
Simplified Irrigation Design — This is the only reference allowed in the testing room, so it needs to be your primary study tool from day one. Read it cover to cover, then work through the sections that correspond to high-weight exam topics. Your score depends on how well you know this book and how fast you can find answers in it under pressure.
Since the exam is open book, the speed at which you find information matters. That's where these two tools pay off:
Redi-Tag Permanent Colored Tabs — You can tab your reference book with permanent index tabs before the exam. These 1.125" x 1.25" laser tabs come in a 100-pack with five colors, so you can color-code by topic — one color for piping, another for layout, another for controls. Temporary tabs like Post-It notes must be removed before you enter the testing room, so go with permanent tabs from the start and skip the extra step.
Sharpie Highlighters — Highlighting key tables, formulas, and friction loss charts lets you find critical information in seconds during the exam. The Sharpie Tank set includes 12 highlighters in six colors with a narrow chisel tip that's precise enough to highlight a single table row without bleeding onto adjacent text.
Study Tips for the MS Irrigation Systems Practice Exam
Target your weak spots, not your comfortable ones. After every practice session, look at which topics you missed. Go back to those first. Re-reading sections you already know doesn't move your score — drilling the gaps does.
Use every minute if you need it. Two hours for 40 questions is generous. Don't rush because someone else finishes early. That's not a signal — some people skip questions they don't know, some people guess and move on. Work at a steady pace, answer every question, and review your work before you submit.
Read each question completely before looking at the answers. Every word in the question stem is there for a reason. Nothing in the question is a trick or a distraction. If a question seems to combine two different topics — say, pipe sizing and water velocity — that's intentional. Finding the connection between them is usually the key to the correct answer.
Practice finding information in your book fast. Tab your friction loss charts, your pipe classification tables, and your wire-sizing charts before test day. On open-book exams, the candidates who struggle most are often the ones who can't find what they're looking for quickly enough.
Get Started: Free Practice Exam
You know the format. You know the topics. Now put it to work. Start with our free practice exam — 10 questions, no account required, no payment needed. It's a quick way to see where you stand before you commit to serious prep. When you're ready to go deeper, the full practice exam matches the real exam format exactly: 40 questions, 120 minutes, with a detailed score breakdown by topic so you know exactly where to focus. The Mississippi irrigation systems exam is achievable — get your book tabbed, hit the weak spots, and go get your license.