Certified Pool Operator Practice Test

102 questions of our own on running a public pool or spa, most answered from CDC's Model Aquatic Health Code.

What is the highest water temperature the Model Aquatic Health Code allows in an aquatic venue, spas included?

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Unofficial practice questions, not affiliated with the Pool & Hot Tub Alliance (PHTA). Bank checked October 10, 2026.

The real course and exam, as PHTA describes them

Valid for
5 years
To earn it
Take the course, pass the exam
Course
16 hours over two days
Where
In person, or virtual where approved
Exam
End of the second day
Questions, time, pass mark
Not published
Covers
The handbook and local codes

Checked October 10, 2026 against the Pool & Hot Tub Alliance's CPO certification, recertification and course pages. Rules change, so confirm with the agency itself before your test.

PHTA's CPO certification page

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All 102 questions

Preventing drowning, illness, entrapment and other hazards 19

  • A diarrheal incident happens in a pool with no cyanuric acid and no secondary treatment. What does the 2024 Model Aquatic Health Code ask for before reopening? 2024 Model Aquatic Health Code (CDC), 6.5.3.2, Diarrheal-Stool Contamination
  • A formed stool is found in a pool that uses no cyanuric acid. Under the 2024 Model Aquatic Health Code, what must be held before reopening? 2024 Model Aquatic Health Code (CDC), 6.5.3.1, Formed-Stool Contamination
  • A venue without lifeguards must provide a reaching pole and a rescue throwing device when its standing water is deeper than: 2024 Model Aquatic Health Code (CDC), 5.8.5.4.1 and 5.8.5.4.2, Throwing Device; Reaching Pole
  • An electrical receptacle without GFCI protection is an imminent health hazard when it is within what distance of the inside wall of the venue? 2024 Model Aquatic Health Code (CDC), 6.6.3.1, item 11, Violations Requiring Immediate Correction or Closure
  • At 1 ppm free chlorine, pH 7.5 and 77°F, with no cyanuric acid, about how long does chlorine take to kill Cryptosporidium? CDC, What to Do When There is Poop in the Pool, table of times to kill germs
Show all 102 questions (97 more)

Preventing drowning, illness, entrapment and other hazards, continued

  • At what pool water depths must deck depth markers carry "No Diving" warning signs and the no-diving symbol? 2024 Model Aquatic Health Code (CDC), 4.5.19.4.1, No Diving Markers, Depths
  • The CT value for Cryptosporidium is 15,300 mg-min/L. If free chlorine is held at 10 ppm, how long is the contact time? 2024 Model Aquatic Health Code (CDC), glossary, CT Inactivation Value, and 6.5.3.2
  • During the opening check a main drain cover is found cracked. What does the Model Aquatic Health Code require? 2024 Model Aquatic Health Code (CDC), 5.7.1.5.1 and 5.7.1.5.1.1, Submerged Drains/Suction Outlet Covers
  • How do people catch Legionella from a hot tub, according to CDC? CDC, About Protecting Yourself from Legionella in Hot Tubs, "Exposure"
  • How often must GFCI devices be tested under the Model Aquatic Health Code's preventive maintenance inspections? 2024 Model Aquatic Health Code (CDC), 6.4.1.3.2, Other Inspection Items
  • How wide a strip of perimeter deck must be kept clear of obstructions around the whole pool? 2024 Model Aquatic Health Code (CDC), 5.8.1.3, Deck Size/Width
  • The inactivation time for a formed-stool incident is 25 minutes without cyanuric acid. The Model Aquatic Health Code doubles it when the water contains cyanuric acid. How long is that? 2024 Model Aquatic Health Code (CDC), 6.5.3.1.1, Pools Containing Chlorine Stabilizers
  • The pool bottom cannot be seen from the deck. Under the Model Aquatic Health Code, what must happen? 2024 Model Aquatic Health Code (CDC), 6.6.3.1, item 14, and 6.6.3.2, Required Closing
  • What does the 2024 Model Aquatic Health Code say about blood in the water of a properly maintained venue? 2024 Model Aquatic Health Code (CDC), 6.5.3.4 and 6.5.3.4.1, Blood-Contamination
  • What is the highest water temperature the Model Aquatic Health Code allows in an aquatic venue, spas included? 2024 Model Aquatic Health Code (CDC), 5.7.4.7.2, Maximum Temperature
  • Which germ was the leading cause of disease outbreaks linked to pools, hot tubs and splash pads in 2015 to 2019? CDC, About the Model Aquatic Health Code, "Why it's important"
  • Which is NOT one of the entrapment types that operator training must cover under the Model Aquatic Health Code? 2024 Model Aquatic Health Code (CDC), 6.1.2.1.4.7, Entrapment Prevention
  • Which storage practice does CDC recommend for pool chemicals? CDC, Pool Chemical Safety, "Chemical storage"
  • Which tool should not be used to take stool out of the water unless its waste goes to a sanitary sewer and it can be disinfected? 2024 Model Aquatic Health Code (CDC), 6.5.2.2 and 6.5.2.2.2, Physical Removal; No Vacuum Cleaners

Regulatory guidelines 11

  • At a pool with no lifeguard, the required sign says a person under what age may not be in the venue without direct supervision by an adult? 2024 Model Aquatic Health Code (CDC), 5.8.5.4.5, Additional Signage
  • The federal drain cover requirement is treated as a consumer product safety rule of which agency? 15 U.S.C. 8003(a), Virginia Graeme Baker Pool and Spa Safety Act
  • In the Model Aquatic Health Code, who is the AHJ? 2024 Model Aquatic Health Code (CDC), glossary, Authority Having Jurisdiction
  • Under OSHA's Hazard Communication standard, where must safety data sheets be kept? 29 CFR 1910.1200(g)(8)
  • Under the federal pool and spa safety law, a public pool with a single main drain that is not unblockable needs at least one more anti-entrapment system. Which of these is on the law's list? 15 U.S.C. 8003(c)(1)(A)(ii), Virginia Graeme Baker Pool and Spa Safety Act
  • Under which federal law must a pool disinfectant or algaecide be registered with EPA? 2024 Model Aquatic Health Code (CDC), 5.7.3, Water Treatment Chemicals and Systems
  • What is the legal standing of CDC's Model Aquatic Health Code? CDC, About the Model Aquatic Health Code, "Policy"
  • What makes someone a "qualified operator" under the Model Aquatic Health Code? 2024 Model Aquatic Health Code (CDC), glossary, Qualified Operator, and 6.1.1.1
  • Which pH reading is an imminent health hazard under the Model Aquatic Health Code? 2024 Model Aquatic Health Code (CDC), 6.6.3.1, items 5 and 6, Violations Requiring Immediate Correction or Closure
  • Which pool counts as a "public pool and spa" under the federal drain cover law? 15 U.S.C. 8003(c)(2), Virginia Graeme Baker Pool and Spa Safety Act
  • Which standard does the federal regulation name today for pool and spa drain covers sold in the United States? 16 CFR 1450.3(a)

Disinfection and water balance 21

  • Above what combined chlorine level must a facility act to bring it down? 2024 Model Aquatic Health Code (CDC), 5.7.4.4.2, Combined Chlorine (Chloramines)
  • According to CDC, what happens as pH drops below 7.0? CDC, Home Pool and Hot Tub Water Treatment and Testing, "pH"
  • At or below what level must cyanuric acid stay in all aquatic venues? 2024 Model Aquatic Health Code (CDC), 5.7.3.1.3.2 and 5.7.3.1.3.3, Stabilizers
  • Combined chlorine is 0.6 ppm. About how much free chlorine must be added to reach breakpoint? 2024 Model Aquatic Health Code (CDC), glossary, Breakpoint Chlorination
  • Cyanuric acid is 90 ppm. What is the lowest free chlorine that keeps the ratio of cyanuric acid to free chlorine from exceeding 45 to 1? 2024 Model Aquatic Health Code (CDC), 6.6.3.1, item 4, Violations Requiring Immediate Correction or Closure
  • Free chlorine above what level, with bathers present, is an imminent health hazard? 2024 Model Aquatic Health Code (CDC), 6.6.3.1, item 3, Violations Requiring Immediate Correction or Closure
  • In what range must total alkalinity be kept? 2024 Model Aquatic Health Code (CDC), 5.7.4.4.1, Total Alkalinity
  • Total chlorine tests at 3.2 ppm and free chlorine at 2.6 ppm. What is the combined chlorine? 2024 Model Aquatic Health Code (CDC), glossary, Chlorine, Combined Available Chlorine
  • Under the Model Aquatic Health Code, calcium hardness must not exceed: 2024 Model Aquatic Health Code (CDC), 5.7.4.4.3 and 5.7.5.6, Calcium Hardness
  • What are chloramines, according to CDC? CDC, Chloramines and Pool Operation, "Key points" and "Overview of chloramines"
  • What does the saturation index describe? 2024 Model Aquatic Health Code (CDC), glossary, Saturation Index, and 5.7.5.8
  • What is hyperchlorination, as the Model Aquatic Health Code defines it? 2024 Model Aquatic Health Code (CDC), glossary, Hyperchlorination; Superchlorination
  • What is the minimum bromine concentration in a spa? 2024 Model Aquatic Health Code (CDC), 5.7.3.1.2.2 and 5.7.3.1.2.3, Minimum and Maximum Bromine Concentrations
  • What is the minimum free chlorine for a pool that does not use cyanuric acid, under the Model Aquatic Health Code? 2024 Model Aquatic Health Code (CDC), 5.7.3.1.1.2.1, Not Using Cyanuric Acid
  • What is the minimum free chlorine for a pool that uses cyanuric acid? 2024 Model Aquatic Health Code (CDC), 5.7.3.1.1.2.2, Using Cyanuric Acid
  • What is the minimum free chlorine for a spa? 2024 Model Aquatic Health Code (CDC), 5.7.3.1.1.2.3, Spas
  • What pH range does the Model Aquatic Health Code require? 2024 Model Aquatic Health Code (CDC), 5.7.3.4.1, pH Range
  • Where does the 2024 Model Aquatic Health Code bar cyanuric acid and stabilized chlorine in new construction? 2024 Model Aquatic Health Code (CDC), 5.7.3.1.3.1, Cyanuric Acid
  • Which chlorine products may be used to raise free chlorine during a fecal or vomit response? 2024 Model Aquatic Health Code (CDC), 6.5.2.3, Treated
  • Which form of free chlorine is the fast, effective biocide in pool water? 2024 Model Aquatic Health Code (CDC), glossary, Chlorine, Free Available Chlorine
  • Which is NOT one of the water balance factors named in the Model Aquatic Health Code's operator course content? 2024 Model Aquatic Health Code (CDC), 6.1.2.1.2.2, Water Balance

Troubleshooting, chemical testing and record keeping 23

  • A 1,200-gallon spa is kept at 102°F, so its turnover time may be no more than 0.5 hours. What is the lowest flow rate that meets it? 2024 Model Aquatic Health Code (CDC), Table 4.7.1.10, Aquatic Venue Maximum Allowable Turnover Times
  • A high-rate sand filter may run at no more than 15 gallons per minute per square foot. For a flow of 300 gallons per minute, what is the smallest filter area? 2024 Model Aquatic Health Code (CDC), 5.7.2.2.1, Filtration Rates
  • A pool feeds disinfectant through an erosion feeder with no automated controller. How often are disinfectant and pH tested while it is open? 2024 Model Aquatic Health Code (CDC), 5.7.5.2, Manual Disinfectant Feed System
  • A pool holds 90,000 gallons and recirculates at 250 gallons per minute. What is its turnover time? 2024 Model Aquatic Health Code (CDC), 4.7.1.10.2, Calculated
  • A rectangular pool is 60 feet long and 30 feet wide, with an average depth of 5 feet. At 7.48 gallons per cubic foot, about how much water does it hold? Arithmetic; gallons per cubic foot from NIST Special Publication 811, Appendix B.9 (gallon and cubic foot)
  • According to CDC, what can a DPD test show when chlorine in the sample is above 10 ppm? CDC, Home Pool and Hot Tub Water Treatment and Testing, "Test the water"
  • After a backwash, how long must the recirculation pump and chemical feeders have run before bathers go back in? 2024 Model Aquatic Health Code (CDC), 5.7.2.2.4.1.1, Backwashing Without Bathers Present
  • An equipment failure interrupts circulation. How long must the interruption last before it has to be written in the daily records? 2024 Model Aquatic Health Code (CDC), 6.4.1.6, item 14, Daily Water Monitoring and Testing Records
  • Cyanuric acid has just been added to a pool. When is its level tested? 2024 Model Aquatic Health Code (CDC), 5.7.5.7 and 5.7.5.7.1, Cyanuric Acid
  • For how long must an aquatic facility keep its operation records? 2024 Model Aquatic Health Code (CDC), 6.4.1.2.1, Record Maintenance
  • For how many hours a day must the filtration and recirculation systems be kept running? 2024 Model Aquatic Health Code (CDC), 5.7.1.1.1, Continuous Operation
  • How far below the surface is a bulk water sample taken? 2024 Model Aquatic Health Code (CDC), 5.7.4.3.1, Obtain Sample
  • How long should a backwash go on? 2024 Model Aquatic Health Code (CDC), 5.7.2.2.3, Clear Water
  • How often are the reagents of a water test kit checked for their expiration date? 2024 Model Aquatic Health Code (CDC), 5.7.3.6.1.1, Expiration Dates
  • How often is total alkalinity tested? 2024 Model Aquatic Health Code (CDC), 5.7.5.5 and 5.7.5.6, Total Alkalinity; Calcium Hardness
  • In a gutter pool with main drains, what share of the design recirculation flow goes through the perimeter overflow system in normal operation? 2024 Model Aquatic Health Code (CDC), 5.7.1.1.3, Gutter / Skimmer Pools
  • What is the longest turnover time allowed for a pool that fits none of the special types in the Model Aquatic Health Code's table? 2024 Model Aquatic Health Code (CDC), Table 4.7.1.10, Aquatic Venue Maximum Allowable Turnover Times
  • What must never be used to clean a cartridge filter? 2024 Model Aquatic Health Code (CDC), 5.7.2.4.3.3.2, Filter Cartridge Cleaning, Pressure Washer
  • When is a granular media (sand) filter backwashed? 2024 Model Aquatic Health Code (CDC), 5.7.2.2.4, Backwashing Frequency
  • When must free chlorine (or total bromine) and pH be tested at every aquatic venue? 2024 Model Aquatic Health Code (CDC), 5.7.5.1, Chemical Parameters
  • Where should the water level sit at a skimmer? 2024 Model Aquatic Health Code (CDC), 5.7.1.4.3 and 5.7.1.4.4, Skimmer Water Levels; Flow
  • Which of these is tested quarterly under the Model Aquatic Health Code? 2024 Model Aquatic Health Code (CDC), 5.7.5.9, Total Dissolved Solids
  • Which record documents each fecal, vomit or blood incident? 2024 Model Aquatic Health Code (CDC), 6.4.1.8.1 and 6.4.1.8.3, Contamination Incidents

Chemical feed 16

  • A liquid feed pump is set to 1.5 gallons per hour and draws from a tank that holds 30 gallons. How long until the tank is empty? Arithmetic from the numbers in the question; feeder sizing is listed in 2024 Model Aquatic Health Code (CDC), 6.1.2.1.3.1, Maintenance Calculations
  • A product label gives a dose of 12 ounces for every 10,000 gallons. The pool holds 45,000 gallons. How much product is the dose? Arithmetic from the numbers in the question; dosing calculation is listed in 2024 Model Aquatic Health Code (CDC), 6.1.2.1.1.1, Disinfectants
  • Before the chlorine or pH feed system is serviced, what does CDC say to turn off? CDC, Pool Chemical Safety, "Maintenance and repair"
  • How must disinfectant and pH control chemicals be delivered to the water under the Model Aquatic Health Code? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.1, Acceptable Chemical Delivery
  • How often are chemical tubing, connections and double containment piping checked for leaks? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.7, Checked Daily
  • The recirculation pump stops during a power cut. What must happen to bathers? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.1.2.1, Response to Alarm and Bather Evacuation
  • Unless the device maker says otherwise, how often is the chemical feeder interlock challenge-tested? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.1.4.1.1, Once Monthly or Specified by Manufacturer
  • What does the 2024 Model Aquatic Health Code say about compressed chlorine gas in new construction? 2024 Model Aquatic Health Code (CDC), 5.7.3.1.4, Compressed Chlorine Gas
  • What is done before an erosion feeder is opened? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.5.1, Erosion Feeders, Opened
  • What must be true of every component of a chemical feed system? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.1.1, Dedicated and Labeled Components
  • What must the interlock on a chemical feed system do? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.1.2, Installed and Interlocked
  • Where must chemical feeders NOT be installed? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.2, Chemical Feeders
  • Which chemicals may be put into an erosion feeder? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.5, Erosion Feeders
  • Which gas does the Model Aquatic Health Code permit as a feed to reduce pH? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.9, Carbon Dioxide
  • Which spare part must be kept onsite for peristaltic liquid feed pumps? 2024 Model Aquatic Health Code (CDC), 5.7.3.5.6, Liquid Solution Feeders
  • Why does CDC say to flush water through chlorine feed tubing before cleaning it with acid? CDC, Pool Chemical Safety, "Maintenance and repair"

Automation and technology 12

  • A pool adds a UV system. How do its required chlorine level and pH change? 2024 Model Aquatic Health Code (CDC), 5.7.3.2.1.3 and 5.7.3.2.2.3, Free Available Chlorine and Bromine Concentrations
  • By how much may a flow turndown system cut the recirculation rate, and when? 2024 Model Aquatic Health Code (CDC), 5.7.1.1.1.1, Reduced Flowrates
  • How must automated controllers be monitored? 2024 Model Aquatic Health Code (CDC), 5.7.3.7.3, Monitor
  • How often is the automated UV shut-down alarm tested? 2024 Model Aquatic Health Code (CDC), 5.7.3.7.9, UV Alarm Testing and Maintenance
  • Residual ozone in the venue's water must stay below: 2024 Model Aquatic Health Code (CDC), 5.7.3.2.2.2, Residual Ozone Concentration
  • Secondary treatment at an interactive water play venue must be designed for what reduction of Cryptosporidium per pass? 2024 Model Aquatic Health Code (CDC), 4.7.3.3.2.1, Log Inactivation
  • What does ORP measure? 2024 Model Aquatic Health Code (CDC), glossary, Oxidation Reduction Potential, and 5.7.3.7.1
  • What is an automated controller? 2024 Model Aquatic Health Code (CDC), glossary, Automated Controller
  • When are in-line ORP readings recorded? 2024 Model Aquatic Health Code (CDC), 5.7.5.4, In-Line ORP Readings
  • When may a UV system operate? 2024 Model Aquatic Health Code (CDC), 5.7.3.2.1.1, Operate with Recirculation System
  • Where is the sample line for a controller's probes placed? 2024 Model Aquatic Health Code (CDC), 5.7.3.7.2, Sampling
  • With an automated disinfectant feed system, how often are disinfectant and pH tested while the venue is open? 2024 Model Aquatic Health Code (CDC), 5.7.5.3, Automatic Disinfectant Feed System

How this list was compiled: Our own questions, grouped by the six "What You'll Learn" topics on the Pool & Hot Tub Alliance's Certified Pool & Spa Operator (CPO) page (https://www.phta.org/education-certification/certification/phta-certified-pool-service-professional-pathway/certified-pool-spa-operator-cpo/). Facts were read in the 2024 Model Aquatic Health Code, 5th Edition, and the Healthy Swimming pages of CDC, in 15 U.S.C. 8003 on govinfo.gov, in 16 CFR 1450.3 and 29 CFR 1910.1200 on ecfr.gov and in NIST Special Publication 811, all on 2026-10-10. Each question names the section it was written from. Licence: Own work. Every question, answer choice and explanation was written for this site from the public sources named on it. Nothing is taken from the exam, from the course handbook or any other material of the Pool & Hot Tub Alliance, or from another practice test.

How it works

This CPO certification practice test follows the six topics the Pool & Hot Tub Alliance (PHTA) lists for its Certified Pool & Spa Operator course. It is unofficial and not affiliated with, endorsed by or sponsored by PHTA.

Read the full guide

Where the answers come from

PHTA says its course follows the latest guidance from CDC and the Council for the Model Aquatic Health Code, among others. So chemistry limits here come from CDC's 2024 Model Aquatic Health Code and drain rules from the federal pool and spa safety law. The course also teaches local codes, and your state or county may set different numbers.

The calculations

Pool volume, turnover, filter area, combined chlorine and contact time are worked from the numbers in the question, and each explanation writes its formula out.

  • Keep the model code's chlorine floors together: 1.0 ppm without cyanuric acid, 2.0 ppm with it, 3.0 ppm in a spa.
  • Turnover is volume divided by flow rate: gallons over gallons per minute, then divide by 60 for hours.

Questions and answers

Is this a practice test for Certified Pool Operator certification?

Yes, an unofficial one. The questions are ours, written from public codes and CDC pages. None comes from the real exam or from PHTA's course handbook, which is a paid book.

How many questions are on the CPO exam?

PHTA's certification page does not publish a question count, a time limit or a pass mark, so this page does not guess them. Your course instructor can tell you what to expect on exam day.

How long does CPO certification last?

PHTA says CPO certification is valid for five years, counted from the end of the month it was issued. A certificate issued on March 2, 2025 expires on March 31, 2030.

Can you take the CPO course online?

Partly. PHTA lists an in-person class, a live virtual class where approved, and a blended format with an online course and one day of class. It is not offered on demand.

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