TCEQ CLASS B SURFACE WATER EXAM QUESTIONS AND
ANSWERS UPDATED 2024/2025 ALL ANSWERS CORRECT
VERIFIED TO SCORE A+
What is the most important factor affecting the useful life of service lines? - CORRECT
ANSWERS It is the ability of the material to resist internal and external corrosion
When does Suction Head exist? - CORRECT ANSWERS Suction head exists when the source of
supply is above the centerline of the pump.
What is Net positive Suction Head (NPSH) - CORRECT ANSWERS NPSH is the pressure under
which water enters the eye of the impeller in a centrifugal pump. Insufficient NPSH is the main
cause of pump cavitation
Explain and expand on Chlorine Dioxide (what it reacts with, oxidizes, etc) - CORRECT ANSWERS
Chlorine Dioxide is a gas used in small quantities to disinfect water. It does not react with
organics to form THMs and HAAs. It oxidizes phenols, manganese, iron, sulfurous and organic
compounds which aids in the removal of tastes and odors. It is a very effective bactericide and a
superior virocide. It dies not combine with ammonia. Chlorine Dioxide MRDL is .8 mg/L and
monitoring procedures are the same as for chlorine. The Chlorite MCL is .q mg/L and must be
monitored daily.
What is texas drinking water pH requirements? - CORRECT ANSWERS The texas drinking water
requirements require a pH > 7.0 for the water treatment plant finished water. EPA requires that
pH analysis be preformed within 15 minutes of the sample being caught.
How does pH affect Chlorine activity? - CORRECT ANSWERS When chlorine is added to water it
forms hypochlorous acid (HOCL) and hydrochloric acid (OCL). The hypochlorous acid is the
effective disinfectant. At a pH of 4.0 there is 100% hypochlorous acid. At a pH of 11 there is
100% hypochlorite ion. At a pH of 7, the hypochlorous acid is at about 80% and the
hypochlorite ion makes up about 20% of the chlorine content. The lower the pH is more
effective chlorine is because you have more hypochlorous acid.
,What is meant by water stability? - CORRECT ANSWERS Stable water is defined as water that
will neither deposit or dissolve a calcium carbonate film or scale. Since no water is stable
indefinitely, chemical treatment of water usually is intended to produce water that is slightly
scale forming without being liable to cause stoppages in small lines and services. Bayliss curve is
the simplest determination of stability. The Langelier saturation index is also used.
What/how are above ground tanks and piping protected from corrosion? - CORRECT ANSWERS
Corrosion protection for above ground tanks and piping is prevented by: cathodic protection,
use if protective linings/coatings, eliminating different types of metals in the distribution
system, and treating the water with chemicals to make it less corrosive
How do you tests fir alkalinity? - CORRECT ANSWERS The two tritiation methods of analysis are
a standard acid to titrate a sample. The end point of the titration is determined by the
following: an indicator that changes color at a certain pH, or potentiometric titration to end -
point pH. Using either of the methods, a measured amount of sample is titrated with a standard
sulfuric acid to a predetermined pH. Nomograph are a graphical form of determining alkalinity.
If the pH, total alkalinity, temperature and total dissolved solids are known, any or all of the
alkalinity forms may be estimated.
What is Turbidity? - CORRECT ANSWERS Turbidity can be described as a measure of the
relative clarity of water. Turbidity is an expression of the optical property that causes light to be
scattered and absorbed rather than transmitted in straight lines through the sample.
What causes Turbidity? - CORRECT ANSWERS Turbidity is caused by clay, slit, finely divided
organic and inorganic material. Other suspended matter and microscopic organisms can also
cause turbidity. There is one approved method for running turbidity - the Nephelometric
Method (NTU)
What is chlorine Demand? - CORRECT ANSWERS The amount of chlorine used up to
completely react with the water and its suspended or dissolve material
What is chlorine residual? - CORRECT ANSWERS When all the demand of the water is met any
additional chlorine produces a chlorine residual
,What is chlorine dosage? - CORRECT ANSWERS Demand plus residual is the chlorine dosage.
Chlorine Dosage = Demand + Residual
What determines rate of disinfection? - CORRECT ANSWERS Chlorine concentration and
contact time determines the rate and degree of disinfection. If concentration increases, the
time can be reduced; if concentration is reduced the time must be increased.
How does temperature effect chlorine effectiveness? - CORRECT ANSWERS Chlorine
effectiveness is greater at higher temperatures, up to the point that chlorine volatizes. At low
temperature, chlorine is more stable, but disinfection time increases.
Is removing turbidity important for disinfection? - CORRECT ANSWERS Turbidity must be
removed to low levels by sedimentation and filtration to allow chlorine to contact pathogens.
What happens to dissolved solids on contact with chlorine? - CORRECT ANSWERS Dissolved
solids are oxidized on contact further reinforcing the importance of contact time.
No residual is formed until reducing agents are destroyed. What are examples of reducing
agents? - CORRECT ANSWERS Manganese, iron, turbidity, organic matter, ammonia, or
nitrates
What the 4 stages of the Chlorine Demand Curve chart? - CORRECT ANSWERS Stage 1: No
residual is formed because inorganic demand destroys the chlorine. (Flat Line)
Stage 2: Monochloramines are formed as chlorine combines with organics containing ammonia
(rising curve). The chlorine to ammonia weight ratio at this point is 5:1. Combined and total
residual increases, chloro-organics are formed.
Stage 3: Increasing chlorine dosage (failing curve) to a chlorine/ammonia weight ratio of 7.6:1
destroys chloramines and chloro-organics. Combined decreases and free chlorine increases.
, Stage 4: Enough chlorine is added to reduce all demand. The combined residual remains the
same, but free residual increases with dosage. This stage is called "breakpoint" chlorination.
The chlorine to ammonia ratio of 10:1 satisfies all demand and disinfects the distribution
system. ( second rising curve)
What is the difference between free chlorine and combined chlorine (chloramines/chlorine-
ammonia) systems? - CORRECT ANSWERS Free chlorine is more powerful than combined
chlorine, but combined chlorine lasts longer.
- combined chlorine requires a 60-minute detention time while free chlorine requires 10
minutes.
-If combined residual is replaced by a free residual, less taste and odor in the water usuals
occurs.
- if combined residual is used : ph and temperature must be monitored closely and the residual
adjusted accordingly. For example, as the temperature decreases the combines residual must
be increased. Free residual does not require such monitoring in the 6.0 - 8.0 pH range. Free
chlorine residual concentration is not affected by temperature changes.
What is the minimum chlorine residual at the far reaches of the system for both free and
combined? - CORRECT ANSWERS Free chlorine residual = .2mg/L
Chloramine (combined) residual = .5 mg/L
- Surface water systems should not exceed a maximum free chlorine or chloramine residual of 4
mg/L as a running average. Limiting residuals reduces disinfection byproducts such as
trihalomethanes and haloacetic acids. These byproducts, consumed over a long period of time,
may cause cancer.
What are the proper techniques for chlorine cylinder storage? - CORRECT ANSWERS - secure
the ton cylinders in a horizontal position and move with a lifting bar and hoist. Never roll them
- 150lbs cylinders shall be chained to rigid support and keep capped unless in use.
ANSWERS UPDATED 2024/2025 ALL ANSWERS CORRECT
VERIFIED TO SCORE A+
What is the most important factor affecting the useful life of service lines? - CORRECT
ANSWERS It is the ability of the material to resist internal and external corrosion
When does Suction Head exist? - CORRECT ANSWERS Suction head exists when the source of
supply is above the centerline of the pump.
What is Net positive Suction Head (NPSH) - CORRECT ANSWERS NPSH is the pressure under
which water enters the eye of the impeller in a centrifugal pump. Insufficient NPSH is the main
cause of pump cavitation
Explain and expand on Chlorine Dioxide (what it reacts with, oxidizes, etc) - CORRECT ANSWERS
Chlorine Dioxide is a gas used in small quantities to disinfect water. It does not react with
organics to form THMs and HAAs. It oxidizes phenols, manganese, iron, sulfurous and organic
compounds which aids in the removal of tastes and odors. It is a very effective bactericide and a
superior virocide. It dies not combine with ammonia. Chlorine Dioxide MRDL is .8 mg/L and
monitoring procedures are the same as for chlorine. The Chlorite MCL is .q mg/L and must be
monitored daily.
What is texas drinking water pH requirements? - CORRECT ANSWERS The texas drinking water
requirements require a pH > 7.0 for the water treatment plant finished water. EPA requires that
pH analysis be preformed within 15 minutes of the sample being caught.
How does pH affect Chlorine activity? - CORRECT ANSWERS When chlorine is added to water it
forms hypochlorous acid (HOCL) and hydrochloric acid (OCL). The hypochlorous acid is the
effective disinfectant. At a pH of 4.0 there is 100% hypochlorous acid. At a pH of 11 there is
100% hypochlorite ion. At a pH of 7, the hypochlorous acid is at about 80% and the
hypochlorite ion makes up about 20% of the chlorine content. The lower the pH is more
effective chlorine is because you have more hypochlorous acid.
,What is meant by water stability? - CORRECT ANSWERS Stable water is defined as water that
will neither deposit or dissolve a calcium carbonate film or scale. Since no water is stable
indefinitely, chemical treatment of water usually is intended to produce water that is slightly
scale forming without being liable to cause stoppages in small lines and services. Bayliss curve is
the simplest determination of stability. The Langelier saturation index is also used.
What/how are above ground tanks and piping protected from corrosion? - CORRECT ANSWERS
Corrosion protection for above ground tanks and piping is prevented by: cathodic protection,
use if protective linings/coatings, eliminating different types of metals in the distribution
system, and treating the water with chemicals to make it less corrosive
How do you tests fir alkalinity? - CORRECT ANSWERS The two tritiation methods of analysis are
a standard acid to titrate a sample. The end point of the titration is determined by the
following: an indicator that changes color at a certain pH, or potentiometric titration to end -
point pH. Using either of the methods, a measured amount of sample is titrated with a standard
sulfuric acid to a predetermined pH. Nomograph are a graphical form of determining alkalinity.
If the pH, total alkalinity, temperature and total dissolved solids are known, any or all of the
alkalinity forms may be estimated.
What is Turbidity? - CORRECT ANSWERS Turbidity can be described as a measure of the
relative clarity of water. Turbidity is an expression of the optical property that causes light to be
scattered and absorbed rather than transmitted in straight lines through the sample.
What causes Turbidity? - CORRECT ANSWERS Turbidity is caused by clay, slit, finely divided
organic and inorganic material. Other suspended matter and microscopic organisms can also
cause turbidity. There is one approved method for running turbidity - the Nephelometric
Method (NTU)
What is chlorine Demand? - CORRECT ANSWERS The amount of chlorine used up to
completely react with the water and its suspended or dissolve material
What is chlorine residual? - CORRECT ANSWERS When all the demand of the water is met any
additional chlorine produces a chlorine residual
,What is chlorine dosage? - CORRECT ANSWERS Demand plus residual is the chlorine dosage.
Chlorine Dosage = Demand + Residual
What determines rate of disinfection? - CORRECT ANSWERS Chlorine concentration and
contact time determines the rate and degree of disinfection. If concentration increases, the
time can be reduced; if concentration is reduced the time must be increased.
How does temperature effect chlorine effectiveness? - CORRECT ANSWERS Chlorine
effectiveness is greater at higher temperatures, up to the point that chlorine volatizes. At low
temperature, chlorine is more stable, but disinfection time increases.
Is removing turbidity important for disinfection? - CORRECT ANSWERS Turbidity must be
removed to low levels by sedimentation and filtration to allow chlorine to contact pathogens.
What happens to dissolved solids on contact with chlorine? - CORRECT ANSWERS Dissolved
solids are oxidized on contact further reinforcing the importance of contact time.
No residual is formed until reducing agents are destroyed. What are examples of reducing
agents? - CORRECT ANSWERS Manganese, iron, turbidity, organic matter, ammonia, or
nitrates
What the 4 stages of the Chlorine Demand Curve chart? - CORRECT ANSWERS Stage 1: No
residual is formed because inorganic demand destroys the chlorine. (Flat Line)
Stage 2: Monochloramines are formed as chlorine combines with organics containing ammonia
(rising curve). The chlorine to ammonia weight ratio at this point is 5:1. Combined and total
residual increases, chloro-organics are formed.
Stage 3: Increasing chlorine dosage (failing curve) to a chlorine/ammonia weight ratio of 7.6:1
destroys chloramines and chloro-organics. Combined decreases and free chlorine increases.
, Stage 4: Enough chlorine is added to reduce all demand. The combined residual remains the
same, but free residual increases with dosage. This stage is called "breakpoint" chlorination.
The chlorine to ammonia ratio of 10:1 satisfies all demand and disinfects the distribution
system. ( second rising curve)
What is the difference between free chlorine and combined chlorine (chloramines/chlorine-
ammonia) systems? - CORRECT ANSWERS Free chlorine is more powerful than combined
chlorine, but combined chlorine lasts longer.
- combined chlorine requires a 60-minute detention time while free chlorine requires 10
minutes.
-If combined residual is replaced by a free residual, less taste and odor in the water usuals
occurs.
- if combined residual is used : ph and temperature must be monitored closely and the residual
adjusted accordingly. For example, as the temperature decreases the combines residual must
be increased. Free residual does not require such monitoring in the 6.0 - 8.0 pH range. Free
chlorine residual concentration is not affected by temperature changes.
What is the minimum chlorine residual at the far reaches of the system for both free and
combined? - CORRECT ANSWERS Free chlorine residual = .2mg/L
Chloramine (combined) residual = .5 mg/L
- Surface water systems should not exceed a maximum free chlorine or chloramine residual of 4
mg/L as a running average. Limiting residuals reduces disinfection byproducts such as
trihalomethanes and haloacetic acids. These byproducts, consumed over a long period of time,
may cause cancer.
What are the proper techniques for chlorine cylinder storage? - CORRECT ANSWERS - secure
the ton cylinders in a horizontal position and move with a lifting bar and hoist. Never roll them
- 150lbs cylinders shall be chained to rigid support and keep capped unless in use.
