CLASS D WATER OPERATOR LICENSE (TCEQ) EXAM 2026
COMPLETE ACTUAL EXAM WITH 180 MOST RECENT
QUESTIONS AND CORRECT VERIFIED ANSWERS/ WATER
OPERATOR CLASS D STUDY GUIDE LATEST
(BRAND NEW!)
The federal regulator of drinking water is the _____. - CORRECT ANSWER ✔✔ -
EPA
T/F: Duties of distribution operator include repairing leaks, making taps, flushing
mains, and taking radiological samples. - CORRECT ANSWER ✔✔ - False (Repair
leaks, Make taps, Flush mains, Operate pumps, Take *bacteriological* samples)
A service area has 1000 service connections. What can we estimate the
population of this service area to be? - CORRECT ANSWER ✔✔ - 3,000 (multiply
connections x 3)
T/F: The State must be notified after an existing facility is changed or after
construction of a new facility. - CORRECT ANSWER ✔✔ - False (must notify
*before*)
T/F: A Class "D" license is valid for 2 years at ground and purchase water systems
with 250 connections or less. - CORRECT ANSWER ✔✔ - False (3 years)
T/F: The physical characteristics of water are color, taste, odor, temperature, and
turbidity. - CORRECT ANSWER ✔✔ - True
1|Page
,An alkaline or basic solution has a pH greater than ____. - CORRECT ANSWER ✔✔
-7
T/F: The terms mg/L and ppm are not interchangeable. - CORRECT ANSWER ✔✔ -
False (they are interchangeable)
Suspended solids in water cannot be filtered out. - CORRECT ANSWER ✔✔ - False
(they can)
Solids, water hardness, pH and gases are ____ characteristics. - CORRECT
ANSWER ✔✔ - Chemical
T/F: There are 2 hydrogen atoms and 1 oxygen atom in each water molecule. -
CORRECT ANSWER ✔✔ - True
T/F: The State recommends a water pH of less than 7 to be maintained at all time.
- CORRECT ANSWER ✔✔ - False (The state recommends a pH slightly greater than
7 and for the water to be non-corrosive.)
T/F: Taste and odor can come from organisms such as vegetation, bacteria, and
algae, and from certain chemicals and metals. - CORRECT ANSWER ✔✔ - True
T/F: The deeper the well, the warmer the water. - CORRECT ANSWER ✔✔ - True
T/F: The threshold odor number (TON) relates to the number of dilutions needed
for the water to be tasteless. - CORRECT ANSWER ✔✔ - False (It reflects the
number of dilutions needed for water sample to be *odorless*)
2|Page
,One part per million or 1 mg/L means that for every ____ pounds of water there
is one pound of material in it. - CORRECT ANSWER ✔✔ - 1 million
The State requires filtered water to be equal to or less than ____ turbidity units in
at least 95% of the monthly samples. - CORRECT ANSWER ✔✔ - 0.3
The State recommends a TON of ___ or less. - CORRECT ANSWER ✔✔ - 3
T/F: The State recommends 20 color units or less for a quality water. - CORRECT
ANSWER ✔✔ - False (The state recommends 15 units of color or less for drinking
water.)
T/F: Examples of inorganic matter found in water include rock, sand, metals, and
minerals. - CORRECT ANSWER ✔✔ - True
T/F: The red color caused by iron is an example of suspended or apparent color
and it can be removed by filtration. - CORRECT ANSWER ✔✔ - True
Excessive calcium and _____ are the primary cause of hardness in water. -
CORRECT ANSWER ✔✔ - Magnesium
T/F: The State recommends a maximum total dissolved solids content of 500 mg/L
- CORRECT ANSWER ✔✔ - False (The state recommends that TDS not exceed 1000
mg/L)
3|Page
, There are 3 common gases found in water: methane, carbon dioxide, and
__________ ___________. - CORRECT ANSWER ✔✔ - hydrogen sulfide
T/F: Turbidity must be limited because it shelters and nourishes bacteria and
interferes with disinfection. - CORRECT ANSWER ✔✔ - True
T/F: Bleach or alcohol require less contact time than flaming to disinfect a faucet.
- CORRECT ANSWER ✔✔ - False (flaming requires less contact time)
T/F: The "primary limits" refer to chemicals with maximum contaminant levels
that can be exceeded. - CORRECT ANSWER ✔✔ - False (refers to chemicals with
maximum contaminant levels (MCLs) that *CANNOT* be exceeded.)
T/F: The term "total coliform" means fecal and non-fecal coliform. - CORRECT
ANSWER ✔✔ - True
T/F: Pathogens are disease-causing microorganisms. - CORRECT ANSWER ✔✔ -
True
If a routine sample is positive, flush the positive sample point, check the chlorine
residual, then resample within 24 days of notification. - CORRECT ANSWER ✔✔ -
False (If a routine sample is total coliform-positive, the PWS should flush the
positive sample point, check the chlorine residual, then resample within *24 hrs*
of notification)
To prevent the formation of THMS in surface water, chlorine is combined with
_____ forming chloramine, combined chlorine residual. - CORRECT ANSWER ✔✔ -
Ammonia
4|Page
COMPLETE ACTUAL EXAM WITH 180 MOST RECENT
QUESTIONS AND CORRECT VERIFIED ANSWERS/ WATER
OPERATOR CLASS D STUDY GUIDE LATEST
(BRAND NEW!)
The federal regulator of drinking water is the _____. - CORRECT ANSWER ✔✔ -
EPA
T/F: Duties of distribution operator include repairing leaks, making taps, flushing
mains, and taking radiological samples. - CORRECT ANSWER ✔✔ - False (Repair
leaks, Make taps, Flush mains, Operate pumps, Take *bacteriological* samples)
A service area has 1000 service connections. What can we estimate the
population of this service area to be? - CORRECT ANSWER ✔✔ - 3,000 (multiply
connections x 3)
T/F: The State must be notified after an existing facility is changed or after
construction of a new facility. - CORRECT ANSWER ✔✔ - False (must notify
*before*)
T/F: A Class "D" license is valid for 2 years at ground and purchase water systems
with 250 connections or less. - CORRECT ANSWER ✔✔ - False (3 years)
T/F: The physical characteristics of water are color, taste, odor, temperature, and
turbidity. - CORRECT ANSWER ✔✔ - True
1|Page
,An alkaline or basic solution has a pH greater than ____. - CORRECT ANSWER ✔✔
-7
T/F: The terms mg/L and ppm are not interchangeable. - CORRECT ANSWER ✔✔ -
False (they are interchangeable)
Suspended solids in water cannot be filtered out. - CORRECT ANSWER ✔✔ - False
(they can)
Solids, water hardness, pH and gases are ____ characteristics. - CORRECT
ANSWER ✔✔ - Chemical
T/F: There are 2 hydrogen atoms and 1 oxygen atom in each water molecule. -
CORRECT ANSWER ✔✔ - True
T/F: The State recommends a water pH of less than 7 to be maintained at all time.
- CORRECT ANSWER ✔✔ - False (The state recommends a pH slightly greater than
7 and for the water to be non-corrosive.)
T/F: Taste and odor can come from organisms such as vegetation, bacteria, and
algae, and from certain chemicals and metals. - CORRECT ANSWER ✔✔ - True
T/F: The deeper the well, the warmer the water. - CORRECT ANSWER ✔✔ - True
T/F: The threshold odor number (TON) relates to the number of dilutions needed
for the water to be tasteless. - CORRECT ANSWER ✔✔ - False (It reflects the
number of dilutions needed for water sample to be *odorless*)
2|Page
,One part per million or 1 mg/L means that for every ____ pounds of water there
is one pound of material in it. - CORRECT ANSWER ✔✔ - 1 million
The State requires filtered water to be equal to or less than ____ turbidity units in
at least 95% of the monthly samples. - CORRECT ANSWER ✔✔ - 0.3
The State recommends a TON of ___ or less. - CORRECT ANSWER ✔✔ - 3
T/F: The State recommends 20 color units or less for a quality water. - CORRECT
ANSWER ✔✔ - False (The state recommends 15 units of color or less for drinking
water.)
T/F: Examples of inorganic matter found in water include rock, sand, metals, and
minerals. - CORRECT ANSWER ✔✔ - True
T/F: The red color caused by iron is an example of suspended or apparent color
and it can be removed by filtration. - CORRECT ANSWER ✔✔ - True
Excessive calcium and _____ are the primary cause of hardness in water. -
CORRECT ANSWER ✔✔ - Magnesium
T/F: The State recommends a maximum total dissolved solids content of 500 mg/L
- CORRECT ANSWER ✔✔ - False (The state recommends that TDS not exceed 1000
mg/L)
3|Page
, There are 3 common gases found in water: methane, carbon dioxide, and
__________ ___________. - CORRECT ANSWER ✔✔ - hydrogen sulfide
T/F: Turbidity must be limited because it shelters and nourishes bacteria and
interferes with disinfection. - CORRECT ANSWER ✔✔ - True
T/F: Bleach or alcohol require less contact time than flaming to disinfect a faucet.
- CORRECT ANSWER ✔✔ - False (flaming requires less contact time)
T/F: The "primary limits" refer to chemicals with maximum contaminant levels
that can be exceeded. - CORRECT ANSWER ✔✔ - False (refers to chemicals with
maximum contaminant levels (MCLs) that *CANNOT* be exceeded.)
T/F: The term "total coliform" means fecal and non-fecal coliform. - CORRECT
ANSWER ✔✔ - True
T/F: Pathogens are disease-causing microorganisms. - CORRECT ANSWER ✔✔ -
True
If a routine sample is positive, flush the positive sample point, check the chlorine
residual, then resample within 24 days of notification. - CORRECT ANSWER ✔✔ -
False (If a routine sample is total coliform-positive, the PWS should flush the
positive sample point, check the chlorine residual, then resample within *24 hrs*
of notification)
To prevent the formation of THMS in surface water, chlorine is combined with
_____ forming chloramine, combined chlorine residual. - CORRECT ANSWER ✔✔ -
Ammonia
4|Page
