AWWA Water Quality Testing 2 — Questions and Answers
Question 1: Which analytical method is the AWWA standard for measuring total organic carbon (TOC) in drinking water?
- High-temperature combustion with IR detection (Correct answer)
- Colorimetric permanganate oxidation
- UV absorbance at 254 nm only
- Titration with potassium dichromate
Correct answer: High-temperature combustion with IR detection
High-temperature combustion with infrared CO2 detection is the EPA-approved and AWWA-referenced standard method for TOC measurement in drinking water.
Question 2: What does a turbidity reading of 0.3 NTU or less at the entry point indicate under the Surface Water Treatment Rule?
- Compliance with the turbidity performance standard (Correct answer)
- The water requires additional coagulation
- Excessive disinfection byproduct formation risk
- Failure of the filtration system
Correct answer: Compliance with the turbidity performance standard
Under the SWTR, filtered water turbidity must not exceed 0.3 NTU in 95% of monthly samples, indicating adequate treatment performance.
Question 3: Which ion is primarily responsible for causing blue-baby syndrome (methemoglobinemia) when present in drinking water at elevated levels?
- Nitrate (Correct answer)
- Fluoride
- Chloride
- Sulfate
Correct answer: Nitrate
Nitrate is converted to nitrite in infants' digestive systems, which oxidizes hemoglobin to methemoglobin, reducing oxygen-carrying capacity.
Question 4: What is the purpose of conducting a jar test in water quality testing?
- Optimize coagulant dose and type before full-scale treatment (Correct answer)
- Measure chlorine residual decay over time
- Determine the hardness of source water
- Assess biological stability of treated water
Correct answer: Optimize coagulant dose and type before full-scale treatment
Jar tests simulate coagulation and flocculation at lab scale to determine the optimal coagulant type and dosage for a given source water.
Question 5: Which parameter is used to calculate the Langelier Saturation Index (LSI) and assess corrosivity of water?
- pH, temperature, calcium hardness, alkalinity, and TDS (Correct answer)
- Turbidity, color, and dissolved oxygen
- Chlorine residual and UV absorbance
- Iron, manganese, and sulfide concentration
Correct answer: pH, temperature, calcium hardness, alkalinity, and TDS
The LSI combines pH, temperature, calcium concentration, total alkalinity, and TDS to determine whether water will tend to deposit or dissolve calcium carbonate scale.
Question 6: During a routine water quality audit, which sample type must be collected first when testing for lead at a consumer's tap?
- First-draw sample after stagnation of at least 6 hours (Correct answer)
- Flush sample after 2 minutes of running water
- Composite sample from multiple taps
- Grab sample from the main service line
Correct answer: First-draw sample after stagnation of at least 6 hours
The Lead and Copper Rule requires a first-draw sample collected after at least 6 hours of no water use to capture lead that may have leached from plumbing.
Question 7: What does a specific conductance measurement indicate about water quality?
- Approximate concentration of dissolved ions (TDS) (Correct answer)
- Presence of disinfection byproducts
- Biological oxygen demand of the water
- Concentration of suspended solids
Correct answer: Approximate concentration of dissolved ions (TDS)
Specific conductance measures the ability of water to conduct electricity, which correlates directly with the concentration of dissolved ions and TDS.
AWWA Water Quality Testing 2
Which analytical method is the AWWA standard for measuring total organic carbon (TOC) in drinking water?