CWEA LABORATORY ANALYST CERTIFICATION
ACTUAL TEST PAPER 2026 COMPLETE
QUESTIONS AND SOLUTIONS GRADED A
◉ Concentration units for chemical and physical results. Answer:
(mass units)/L.
◉ Conductance measurements. Answer: Temperature compensated
to 25 degrees C.
◉ Conductivity meter calibration. Answer: Calibrated with 0.0100 N
potassium chloride standard.
◉ Conductivity of pure water. Answer: 0
◉ Confirmed phase for standard coliform fermentation technique.
Answer: Use brilliant green lactose bile broth; add dehydrated
ingredients, mix, heat to dissolve; before sterilization, dispense
durham tube in fermentation tubes, sufficient medium to cover
durham 1/2 to 2/3 after sterilization, close tubes with metal or heat
resistant plastic caps; autoclave at 121 C for 12 to 15 minutes; pH
should be 7.2 +/- 0.2 after sterilization.
,◉ Constant weight for total solids. Answer: Weight change is less
than 4% of previous weight or 0.5 mg.
◉ Definition of pH. Answer: The negative logarithm of the hydrogen
ion concentration in moles per liter.
◉ Dilution water preparation for BOD. Answer: DO concentration is
7.5 mg/L; add 1 mL each of phosphate buffer, MgSO4, CaCl2, and
FeCl3 solution/L to prepared source water.
◉ Disinfection. Answer: Process designed to kill most
microorganisms in wastewater, including all essentially pathogenic
bacteria.
◉ Drinking water set up. Answer: 10 replicate tube each containing
10 mL; 5 replicate tubes containing 20 mL.
◉ During acid base titration. Answer: Titrant is added to the sample
with Buret.
◉ Endpoint of EDTA titrimetric method for hardness. Answer:
Indicator turns red to purple, meaning all Ca and Mg have been
chelated.
, ◉ Enzyme Substrate Coliform Test. Answer: Utilizes hydrolyzable
substrates to detect total coliform bacteria and E Coli.
◉ Enzyme test of E Coli. Answer: Bacteria giving positive total
coliform response and possessing enzyme B-glucuronidase, cleaves
fluorogenic substrate, releasing fluorogen.
◉ Enzyme test of total coliform bacteria. Answer: All bacteria
possessing the enzyme B-D-galactosidase, cleaves chromogenic
substrate, releasing chromogen.
◉ EPA acceptable primary standards for turbidity determination.
Answer: Formazine only.
◉ Fecal coliform bacteria. Answer: Bacteria found in feces of warm
blooded animals.
◉ Fecal coliform is aka. Answer: Thermotolerant coliforms.
◉ Field log books should include. Answer: Purpose of sampling,
location of sampling point, name and address of field contact,
producer of material being sampled and address, type of sample,
method, date, and time of preservation.
ACTUAL TEST PAPER 2026 COMPLETE
QUESTIONS AND SOLUTIONS GRADED A
◉ Concentration units for chemical and physical results. Answer:
(mass units)/L.
◉ Conductance measurements. Answer: Temperature compensated
to 25 degrees C.
◉ Conductivity meter calibration. Answer: Calibrated with 0.0100 N
potassium chloride standard.
◉ Conductivity of pure water. Answer: 0
◉ Confirmed phase for standard coliform fermentation technique.
Answer: Use brilliant green lactose bile broth; add dehydrated
ingredients, mix, heat to dissolve; before sterilization, dispense
durham tube in fermentation tubes, sufficient medium to cover
durham 1/2 to 2/3 after sterilization, close tubes with metal or heat
resistant plastic caps; autoclave at 121 C for 12 to 15 minutes; pH
should be 7.2 +/- 0.2 after sterilization.
,◉ Constant weight for total solids. Answer: Weight change is less
than 4% of previous weight or 0.5 mg.
◉ Definition of pH. Answer: The negative logarithm of the hydrogen
ion concentration in moles per liter.
◉ Dilution water preparation for BOD. Answer: DO concentration is
7.5 mg/L; add 1 mL each of phosphate buffer, MgSO4, CaCl2, and
FeCl3 solution/L to prepared source water.
◉ Disinfection. Answer: Process designed to kill most
microorganisms in wastewater, including all essentially pathogenic
bacteria.
◉ Drinking water set up. Answer: 10 replicate tube each containing
10 mL; 5 replicate tubes containing 20 mL.
◉ During acid base titration. Answer: Titrant is added to the sample
with Buret.
◉ Endpoint of EDTA titrimetric method for hardness. Answer:
Indicator turns red to purple, meaning all Ca and Mg have been
chelated.
, ◉ Enzyme Substrate Coliform Test. Answer: Utilizes hydrolyzable
substrates to detect total coliform bacteria and E Coli.
◉ Enzyme test of E Coli. Answer: Bacteria giving positive total
coliform response and possessing enzyme B-glucuronidase, cleaves
fluorogenic substrate, releasing fluorogen.
◉ Enzyme test of total coliform bacteria. Answer: All bacteria
possessing the enzyme B-D-galactosidase, cleaves chromogenic
substrate, releasing chromogen.
◉ EPA acceptable primary standards for turbidity determination.
Answer: Formazine only.
◉ Fecal coliform bacteria. Answer: Bacteria found in feces of warm
blooded animals.
◉ Fecal coliform is aka. Answer: Thermotolerant coliforms.
◉ Field log books should include. Answer: Purpose of sampling,
location of sampling point, name and address of field contact,
producer of material being sampled and address, type of sample,
method, date, and time of preservation.
