TCEQ Class B Surface Water Exam Preparation
TCEQ CLASS B SURFACE WATER EXAM PREPARATION FOR
2025/2026 COMPLETE 200 QUESTIONS AND CORRECT
ANSWERS |ALREADY GRADED A+||BRAND NEW!!
What is Turbidity?
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?
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?
The amount of chlorine used up to completely react with the water and its
suspended or dissolve material
What is chlorine residual?
When all the demand of the water is met any additional chlorine produces a
chlorine residual
What is chlorine dosage?
Demand plus residual is the chlorine dosage. Chlorine Dosage = Demand +
Residual
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, TCEQ Class B Surface Water Exam Preparation
What determines rate of disinfection?
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?
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?
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?
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?
Manganese, iron, turbidity, organic matter, ammonia, or nitrates
What the 4 stages of the Chlorine Demand Curve chart?
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, TCEQ Class B Surface Water Exam Preparation
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?
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.
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, TCEQ Class B Surface Water Exam Preparation
What is the minimum chlorine residual at the far reaches of the system for both
free and combined?
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?
- 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.
- Check all chlorine systems for leaks before putting into service with a 10%
ammonia solution. Household ammonia is not approved. When ammonia contacts
chlorine gas white smoke results.
What are the steps to do before entering a room with a chlorine leak?
1: notify other operators and have standby help for possible notification of
emergency personnel
2: Be trained in emergency procedures and have knowledge of chlorinators, tools,
and ammonia use.
3: Put on a self-contained breathing apparatus (SCBA)
4: wear a safety harness and lifeline
4|Page
TCEQ CLASS B SURFACE WATER EXAM PREPARATION FOR
2025/2026 COMPLETE 200 QUESTIONS AND CORRECT
ANSWERS |ALREADY GRADED A+||BRAND NEW!!
What is Turbidity?
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?
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?
The amount of chlorine used up to completely react with the water and its
suspended or dissolve material
What is chlorine residual?
When all the demand of the water is met any additional chlorine produces a
chlorine residual
What is chlorine dosage?
Demand plus residual is the chlorine dosage. Chlorine Dosage = Demand +
Residual
1|Page
, TCEQ Class B Surface Water Exam Preparation
What determines rate of disinfection?
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?
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?
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?
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?
Manganese, iron, turbidity, organic matter, ammonia, or nitrates
What the 4 stages of the Chlorine Demand Curve chart?
2|Page
, TCEQ Class B Surface Water Exam Preparation
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?
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.
3|Page
, TCEQ Class B Surface Water Exam Preparation
What is the minimum chlorine residual at the far reaches of the system for both
free and combined?
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?
- 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.
- Check all chlorine systems for leaks before putting into service with a 10%
ammonia solution. Household ammonia is not approved. When ammonia contacts
chlorine gas white smoke results.
What are the steps to do before entering a room with a chlorine leak?
1: notify other operators and have standby help for possible notification of
emergency personnel
2: Be trained in emergency procedures and have knowledge of chlorinators, tools,
and ammonia use.
3: Put on a self-contained breathing apparatus (SCBA)
4: wear a safety harness and lifeline
4|Page
