Newsletter #251 for October 29, 2019
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Test Your Operator Knowledge!

Preparing for your operator certification exam can seem stressful and intimidating for many new operators or those who are working toward a higher certification class. In this month's Special Edition Newsletter, we hope to remove some of the pressure by providing helpful study resources for both drinking water and wastewater. If these resources don't meet all your study needs, check out a previous blog post we've written on test prep resources.

Below, you will find two sample quizzes, one for water and one for wastewater. The questions cover a range of topics including treatment, monitoring, collections or distribution, regulations, safety, and a few tricky math problems. We've also provided a detailed answer key with links that will help you learn more.

In addition to our practice quizzes, we've included some helpful test taking tips and a list of resources at the bottom of the newsletter to link you to more practice exams. We've only included exams that provide an answer key. Many of these links also provide explanation of the results. Please enjoy these test taking resources and get ready to test your knowledge!
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Test Taking Tips

When the time comes to take your certification exam, remember these helpful test taking tips!

Prepare for the Exam:

  1. Make a Study Plan
    The AWWA Study Tactics fact sheet recommends studying 2-4 times a day after submitting your application. Research study techniques to find the ones that work for you. It's important to understand the study material, not just memorize.
  2. Research the Exam
    Know what the format the exam will look like and what tools and materials you can bring or use during the test. If you're taking the computerized exams, the Association of Boards of Certification has developed an online exam demo that includes practice problems to help you prepare.
  3. Before the Exam
    Get a good night's sleep the night before your test. Drink water and have a healthy meal in the morning. High protein foods can aid in concentration.
  4. Arrive Early
    Arrive early to use the bathroom and relax your mind before the test starts.
Taking the Test:
  1. Stay Positive and Calm
    When you start the exam, take a deep breath and eliminate any negativity. Any time you become anxious during the test, take a deep breath to clear your mind.
  2. Skim Over the Test Before Starting
    Read the instructions carefully and skim through the questions to estimate how you will want to distribute your time. 
  3. Read Each Question Carefully.
    Carefully read each question in its entirety before trying to answer it. Carefully read and consider each multiple choice answer as well.
  4. Process of Elimination
    Eliminate any answers that you know are incorrect. This can only increase you chances of getting a question right.
  5. Skip Difficult Questions
    Don't waste all of your time on one hard problem. When you find a difficult question, move on and make a note to return to it at the end.
  6. Pace Yourself
    While you don't want to be too focused on how much time has passed, check the clock periodically to make sure you will be able to get to every question. 
  7. Review Your Answers
    If you have time at the end, double check for silly mistakes. Don't second-guess yourself unless you are certain that an answer needs to be changed.
  8. Ignore Participants Who Finish Before You
    Research shows that students who finish early usually don't score as well as those who take more time.
After the Exam:
Take time to relax after the test. You've put a lot of hard work into preparing for this exam and now it's time to for some self care.

Drinking Water Practice Problems

Below is a list of drinking water study questions to test your knowledge for the certification exam. Use this AWWA unit conversion sheet to help with any math questions. Write your answers as you go and scroll down to see if you're correct.

Drinking Water Practice Questions

1. What is the correct definition of a Public Water system?

     a. A system that provides water for human consumption to at least 10 service connections or serves an average of at least 25 people for at least 60 days per year.

     b. A system that provides water for human consumption to at least 15 service connections or serves an average of at least 25 people for at least 30 days per year.

     c. A system that provides water for human consumption to at least 15 service connections or serves an average of at least 25 people for at least 60 days per year.

2. True or False: A public water system may be publicly or privately owned.

3. True or False: The maximum contaminant level (MCL) for lead is 0.015 mg/L.

4. A reservoir level is 32 meters above the pump discharge. What is the discharge pressure of the pump in terms of pounds per square inch (psi)?

5. If one calcium hypochlorite tablet added to 450 gallons of water results in an increase of 100 mg/L of chlorine, how many tablets are required to dose a 35,000-gallon tank to 50 mg/L? TRICKY!

6. Water hardness is a measure of which two dissolved constituents?

Iron and Manganese

b. Calcium and Magnesium Carbonates

c. Sulfates and Bicarbonates

7. Under Section 2013 of the America's Water Infrastructure Act, drinking water systems serving 3,300 people or more are required to do which of the following?

a. Conduct or update a single risk & resilience assessment with a one-time certification due by the date specified for their system size.

b. Conduct a risk & resilience assessment using the results to produce an emergency response plan. Review both requirements every five years after certification.

c. Develop or update an emergency response plan that should be maintained by the system for three years after certification.

8. A bacteria or bacteria group that exclusively inhabits the intestines of warm-blooded animals.

a. E. coli

b. Total coliform

c. Klebsiella

9. What is the chemical formula for calcium hypochlorite?

a. Ca2(ClO)2

b. CaClO2

c. Ca(ClO)2

10. When collecting a sample for bacteriological testing, how long should the operator let water run for before collecting the sample?

a. The sample should be collected immediately to ensure flushing does not impact the sample results.

b. 30 minutes

c. As long as necessary to clear service lines for collection.

Drinking Water Answer Key

1. The correct answer is C. 
A  public water system provides water for human consumption to at least 15 service connections or serves an average of at least 25 people for at least 60 days per year. Source.

2. True.
According the EPA a public water system (PWS) may be publicly or privately owned. There are three classes of PWS: Community Water System, Non-Transient Non-Community Water System, and Transient Non-Community Water System. Source.

3. False
Lead is regulated by an action level (AL), not an MCL. The AL for lead is 0.015 mg/L. Lead and copper are regulated by a treatment technique that requires systems to control corrosion. If more than 10% of tap water samples exceed the action level, water systems must take additional steps. Source.

4. 45 psi
Water pressure is measured in psi and feet of head. A column of water 2.31 feet high creates a pressure of 1 psi so if the height of the water column is known, psi can be determined.
psi x 2.31 = Feet of Head or psi = (Feet of Head) / 2.31
The head was given as 32 meters. Convert meters into feet.
32 m x 3.28 ft/m = 104.96 ft
Plug feet into the psi equation
psi = 104.96 ft / 2.31 = 45.4 psi
Source (pg 68).

5. 39 tablets
Step 1: Find the pounds of chlorine per tablet
Convert the 100 mg/L dose into pounds per million gallons using the following equation:
eq 1: (mg/L) x 8.345 = (lb/mill gal)
100 mg/L x 8.345 = 834.5 lb/mill gal
Convert the tank volume of 450 gallons of water into the units 'million gallons' 
450 / 1,000,000 =  0.00045 mill gal
Multiply the chlorine dose in lb/mill gal by the volume in mill gal to get pounds of chlorine
834.5 lb/mill gal x 0.00045 mill gal= 0.375525 lb
Divide the pounds of chlorine calculated by the number of tablets used to get lb/tablet
0.375525 lb / 1 tablet = 0.375525 lb/tablet
Step 2: Find the number of tablets for the new tank size
Convert the new 50 mg/L dose into the units of lb/mill gal with equation 1
50 mg/L x 8.345 = 417.25 lb/mill gal
Convert the new 35,000 gallons into units of million gallons
35,000 / 1,000,000 = 0.035 mill gal
Use the chlorine dose in lb/mill gal and the volume in mill gal to get pounds of chlorine
417.25 lb/mill gal x 0.035mill gal= 14.60375 lb
Use the lb/tablet value calculated in step 1 to find the number of tablets needed for the new tank
tablets = 14.60375 lb / 0.375525 lb/tablet = 38.9 tablets

6. The correct answer is B.
Hardness in drinking water is comprised of calcium and magnesium. There are no health risks from water hardness., however, too much can create aesthetic issues including: scale, soap scum, and white mineral deposits. Source

7. The correct answer is B.
The Act requires systems serving 3,300 people or more to develop or update a risk assessment using the results to develop or update an emergency response plan (ERP). Both should be retained by the system for at least five years after certifying their completion to the EPA. Each system must review and revise if necessary both the assesment and ERP at least once every five years. Source

8. The correct answer is A.
Total coliforms include types of bacteria that grow in soil, water, or animal waste. E. coli is a type of coliform (fecal coliform) bacteria that specifically grows in the gut and feces of warm-blood animals. Klebsiella is a type of coliform bacteria that can be found everywhere in nature. Source.

9. The correct answer is C.
Ca(ClO)2 is the correct formulaSource.

10. The correct answer is C.
To collect bacteriological samples wear gloves and do not rinse the sterile bottles. Once the distribution line is flushed and the flow reduced, quickly open the bottle holding the cap by its outside edges only. Fill the sample bottle to just above the 100 mL line leaving a one inch head space. Cap immediately and place it into a cooler for delivery. Source.

Wastewater Practice Problems

Below is a list of wastewater study questions to test your knowledge for the certification exam. Use this AWWA unit conversion sheet to help with any math questions. Write your answers as you go and scroll down to see if you're correct.

Wastewater Practice Questions

1. The microbial process in which bacteria oxidize ammonia and reduced nitrogen compounds into nitrites and nitrates.

a. Aeration

b. Nitrification

c. Denitrification

2. True or False: The rotating element in a centrifugal pump is commonly called a volute chamber.

3. Which of the following diseases is not considered to be waterborne?

a. Typhoid

b. Parathyroid types A and B

c. Cholera

4. Calculate chlorine demand, given that the plant flow is 12.5 MGD, the total daily use is 1,300 lb/day, and the effluent chlorine residual is 2.5 mg/L.

5. What is the minimum recommended dissolved oxygen concentration required for biological nitrification in an aeration tank?

a. 2.0 mg/L

b. 0.5 mg/L

c. 1.0 mg/L

6. During permit required confined space entry, atmospheric testing is required...

a. before entering the confined space.

b. while the confined space is occupied by entrants.

c. Both a and b.

7. A piston pump that is used to move sludge into a centrifuge has a 1 foot bore and a 6 inch stroke. During a 5 hour period, the stroke counter on the pump read 475 stroke. How many gallons of sludge were pumped?

8. What should be used to cover the embankment of stabilization ponds?

a. Grass with shallow roots

b. Deeply rooted grasses

c. Trees such as willow or cottonwood

9. True or False: The chemical formula for ammonium is NH3.

10.  What is the maximum holding time for a suspended solids sample?

a. 2 days

b. 5 days

c. 7 days

Wastewater Answer Key

1. The correct answer is B.
Nitrification is the process where reduced nitrogen compounds, primarily ammonia, are oxidized to nitrite and nitrate through Nitrosomonas and Nitrobacters. Source

2. False
Fluid enters the pump impeller along the rotating axis and is accelerated by the impeller. Fluid flows radially outward into a diffuser or volute chamber where it exits. Source.

3. The correct answer is B.
Typhoid fever is caused by the bacteria Salmonella Typhi. Cholera is caused by the bacteria Vibrio cholerae. Both can be spread through contact with infected people, food, and contaminated water. Source 1Source 2.

4. 1,039 lb/day 
eq 1: Supply - Demand = Residual or Demand = Supply - Residual
The value for supply is given at 1,300 lb/day.
eq 2: Residual = Plant Flow x Chlorine Residual
First convert Chlorine Residual into pounds/ million gallons
2.5 mg/L x 8.345 = 20.8625 pounds/million gallons (lb/mill gal)
Plug in the given Plant Flow and the converted Chlorine Residual value into equation 2
Residual = 12.5 mill gal/day x 20.8625 lb/mill gal = 260.8 lb/day
Plug Residual and Supply into equation 1 to find Demand:
Demand = 1,300 lb/day - 260.8 lb/day = 1039.2 lb/day 

5. The correct answer is C.
Dissolved oxygen levels should be maintained at 1-3 mg/L for effective treatment. Source

6. The correct answer is C.
Any confined space must be tested for a hazardous atmosphere before entry. Monitoring must continue while the entrants are in the confined space. Source.

7. 1395 gallons
Step 1: Find the gallons/ stroke
Convert the stroke into feet
6 ft / 12 in/ft = 0.5 ft
Calculate right cylinder volume using the following equation:
eq 1: Volume in cubic feet = 0.785 x (diameter in ft)^2 x (height in ft)
Plug in the given values for depth (height) and diameter in units of feet into equation 1.
V = 0.785 x (1 ft)^2 x (0.5 ft) = 0.3925 cubic feet
Convert cubic feet into gallons
0.3925 ft^3 x 7.48052 gal/ft^3 = 2.936 gallons in one stroke
Step 2: Multiply the number of strokes by the volume/ stroke to get the gallons pumped
2.936 gallons/ stroke x 475 strokes = 1394.6 gallons

8. The correct answer is A. 
A dense, short-rooted grass should be established and well maintained on lagoon embankments to prevent erosion. Water loving grasses such as canary grass or alfalfa should be avoided. Weeds, trees, and deep-rooted plants can penetrate soil impairing water holding capacity. Source.

9. False
The chemical formula for ammonium is NH4+. This is the ionized form of ammonia which has the chemical formula NH3. Source.

10.  The correct answer is C.
TSS samples should be kept in a polyethylene, fluoropolymer, or glass bottle at a max temperature of 6 degrees Celsius for a maximum holding time of 7 days. Source.

Practice Test Resources

Using's resource library, operators can find a plethora of additional free study resources for both drinking water and wastewater. Some of our favorite practice test resources include:

TPO Magazine's Online Study Guide Series 
by Treatment Plant Operator (TPO) Magazine
This study guide series regularly releases a pair of water and wastewater study questions with a detailed explanation of the answers.

Certification Boulevard Quiz Compilation
by Florida Water Environment Association
This web page links to water and wastewater practice quizzes that were offered in the Florida Water Resources Journal from 2000 to 2014.

Online Resource Library: Drinking Water & Wastewater Practice Exams
by Idaho Rural Water Association (IRWA)
IRWA has created practice exams on basic math, distribution, water treatment, wastewater treatment, collections, and land application. Answer keys are included.

Operator Math- Certification Exam Review Playlist
It can be hard to find study material that teaches you how to work through difficult math problems. We've created this playlist so you find clear step by step math tutorials.

Operator Math Review - Continuing Education Professional Development Course
by Technical Learning College
If you're struggling with knowing the right math terminology or how to select the right equation to solve a problem, check out this review guide. 

Study Help: Division of Drinking Water
by Utah Department of Environmental Quality
This web-page links to study guides and presentations on distribution and water treatment. The guides themselves do not have an answer key, however the presentations contain the answers.

Study Time: Wastewater 101
The Wastewater101 blog regularly posts new study questions with their answers. Any math related questions include a walk-through of how to solve the problem.

Want to find more free, online test taking resources?
Search the Document Database
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Groundwater & Well Care for Public Water Systems is a free online course from Certificates are provided and the course is currently pre-approved for 2 hours continuing education credit in a number of states.

Click here to learn more.

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