1|Page
TCEQ Class D Water Operator License Exam 2025 – Study
Guide, Practice Questions & Test Prep
Prepare for your TCEQ Class D Water Operator License Exam 2025 with this comprehensive
study guide, featuring water treatment principles, regulatory standards, sample questions,
and exam strategies to help candidates pass confidently and earn their Class D certification.
• TCEQ Class D Water Operator License
• TCEQ Class D exam prep
• Texas water operator certification
• TCEQ Class D practice questions
The two pathogenic protozoans resistant to chlorination are: ________ and _________ - ANSWER-
giardia / cryptosporidium
T/F: Bacteria, algae, and turbidity can be a problem in surface water as can be municipal, industrial and
agricultural pollution. - ANSWER-True
T/F: Coagulation works by the bonding of negatively charged turbidity to positively charged chemical
coagulants. - ANSWER-True
T/F: Turbidity can shelter bacteria from the disinfection process. - ANSWER-True
_______ is the last treatment step before storage. - ANSWER-Disinfection
T/F: Treated water is stored at the plant in a tank called a clear well. - ANSWER-True
,2|Page
The process of separating floc from water by gravity is called: __________ - ANSWER-sedimentation
Filtration is the last barrier between the public and _______ or ________. - ANSWER-giardia /
cryptosporidium
T/F: If the media collects in the wash water troughs, the wash rate is too high. - ANSWER-True
T/F: A check valve located on the discharge side of a pump is an isolating valve that allows water to flow
one direction only. - ANSWER-False (it is a *controlling valve*)
T/F: The total dynamic head a pump must overcome is the distance from the water level on the suction
side of the pump to the top of the water level on the discharge side of the pump and includes any
friction and head loss encountered. - ANSWER-True
Destratification is the mixing of lake water by compressed air to prevent layers of different __________
from developing. - ANSWER-temperature
All PWS in Texas are required to use ________ as the final disinfectant. - ANSWER-chlorine
T/F: Powdered activated carbon (PAC) is commonly used to treat iron and manganese. - ANSWER-False
(removes the tastes and odors usually caused by dead and decaying *algae* and vegetation)
A restricted zone of ______ ft radius from the raw water intake must be established and recreational
activities and trespassing shall be prohibited. - ANSWER-200
T/F: The Rio Grande River is the longest river in Texas, stretching 250 miles along the Mexico border. -
ANSWER-False (1250 miles)
T/F: Filtration is the first step in the removal of suspended solids. - ANSWER-False (Sedimentation)
Surface water is usually low in ________ and ________. - ANSWER-minerals / gases
, 3|Page
Chemical dosage, water temperature, pH, _______, and the characteristics of the raw water all have an
effect on the coagulation process. - ANSWER-mixing
Dead-end mains must be provided with ________ - ANSWER-Flush valves
T/F: Common cross connections include a garden hose connected to a potable water source and
submerged in a stock tank, a home served by a city water supply and private well, and a chemical
container connected to a potable water supply. - ANSWER-True
T/F: If a repaired main must be returned to service quickly, does with 50 mg/L for 30 minutes. - ANSWER-
False (*500 mg/L*)
T/F: TCEQ requires at least 1 BacT sample for each 1000 ft of new main. - ANSWER-True
Pipe and fittings must not contain more than ____% lead or solderandflux containing more than ___%
lead. - ANSWER-8.0%
0.2%
The _________ is TCEQ's first choice to be used for backflow prevention when health hazards are
involved and protect against sewage contaminations. - ANSWER-air gap
Service tap components usually include a tapping saddle, corporation stop, service line tubing, curb stop,
and _______. - ANSWER-meter
T/F: A distribution system without dead ends is called an open system - ANSWER-False (looped system)
An intruder-resistant fence with lockable gates must enclose the storage site. - ANSWER-True
T/F: Ground water supply systems serving more than 50 connections must have a
TCEQ Class D Water Operator License Exam 2025 – Study
Guide, Practice Questions & Test Prep
Prepare for your TCEQ Class D Water Operator License Exam 2025 with this comprehensive
study guide, featuring water treatment principles, regulatory standards, sample questions,
and exam strategies to help candidates pass confidently and earn their Class D certification.
• TCEQ Class D Water Operator License
• TCEQ Class D exam prep
• Texas water operator certification
• TCEQ Class D practice questions
The two pathogenic protozoans resistant to chlorination are: ________ and _________ - ANSWER-
giardia / cryptosporidium
T/F: Bacteria, algae, and turbidity can be a problem in surface water as can be municipal, industrial and
agricultural pollution. - ANSWER-True
T/F: Coagulation works by the bonding of negatively charged turbidity to positively charged chemical
coagulants. - ANSWER-True
T/F: Turbidity can shelter bacteria from the disinfection process. - ANSWER-True
_______ is the last treatment step before storage. - ANSWER-Disinfection
T/F: Treated water is stored at the plant in a tank called a clear well. - ANSWER-True
,2|Page
The process of separating floc from water by gravity is called: __________ - ANSWER-sedimentation
Filtration is the last barrier between the public and _______ or ________. - ANSWER-giardia /
cryptosporidium
T/F: If the media collects in the wash water troughs, the wash rate is too high. - ANSWER-True
T/F: A check valve located on the discharge side of a pump is an isolating valve that allows water to flow
one direction only. - ANSWER-False (it is a *controlling valve*)
T/F: The total dynamic head a pump must overcome is the distance from the water level on the suction
side of the pump to the top of the water level on the discharge side of the pump and includes any
friction and head loss encountered. - ANSWER-True
Destratification is the mixing of lake water by compressed air to prevent layers of different __________
from developing. - ANSWER-temperature
All PWS in Texas are required to use ________ as the final disinfectant. - ANSWER-chlorine
T/F: Powdered activated carbon (PAC) is commonly used to treat iron and manganese. - ANSWER-False
(removes the tastes and odors usually caused by dead and decaying *algae* and vegetation)
A restricted zone of ______ ft radius from the raw water intake must be established and recreational
activities and trespassing shall be prohibited. - ANSWER-200
T/F: The Rio Grande River is the longest river in Texas, stretching 250 miles along the Mexico border. -
ANSWER-False (1250 miles)
T/F: Filtration is the first step in the removal of suspended solids. - ANSWER-False (Sedimentation)
Surface water is usually low in ________ and ________. - ANSWER-minerals / gases
, 3|Page
Chemical dosage, water temperature, pH, _______, and the characteristics of the raw water all have an
effect on the coagulation process. - ANSWER-mixing
Dead-end mains must be provided with ________ - ANSWER-Flush valves
T/F: Common cross connections include a garden hose connected to a potable water source and
submerged in a stock tank, a home served by a city water supply and private well, and a chemical
container connected to a potable water supply. - ANSWER-True
T/F: If a repaired main must be returned to service quickly, does with 50 mg/L for 30 minutes. - ANSWER-
False (*500 mg/L*)
T/F: TCEQ requires at least 1 BacT sample for each 1000 ft of new main. - ANSWER-True
Pipe and fittings must not contain more than ____% lead or solderandflux containing more than ___%
lead. - ANSWER-8.0%
0.2%
The _________ is TCEQ's first choice to be used for backflow prevention when health hazards are
involved and protect against sewage contaminations. - ANSWER-air gap
Service tap components usually include a tapping saddle, corporation stop, service line tubing, curb stop,
and _______. - ANSWER-meter
T/F: A distribution system without dead ends is called an open system - ANSWER-False (looped system)
An intruder-resistant fence with lockable gates must enclose the storage site. - ANSWER-True
T/F: Ground water supply systems serving more than 50 connections must have a
