1|Page
CWEA Grade 1 Lab Analyst Exam 2025 — Free
Study Guide, Practice Test Questions, and
Certification Preparation
Get ready for the CWEA Grade 1 Lab Analyst Exam 2025 with the latest study guide, free
practice test questions, and certification prep materials. Learn essential topics in water
quality analysis, laboratory safety, wastewater treatment, and sample testing to pass your
California Water Environment Association (CWEA) certification exam easily.
• CWEA Grade 1 Lab Analyst Exam 2025
• CWEA Lab Analyst practice test
• CWEA Grade 1 study guide
• CWEA certification exam questions
Analysis procedure of total suspended solids - ANSWER-1. Wet filter to seat it
2. Pipet measured volume to filter
3. Wash filter with 3 successive 10 mL wash of reagent grade water and continue suction for 3 minutes
4. Dry for 1 hour in 103-105 degree C oven
5. Cool in desicator and weigh until constant weight
Coliform density using fermentaion techniques can be estimated using - ANSWER-Most probable
number table
Drinking water set up - ANSWER-- 10 replicate tube each containing 10 mL
- 5 replicate tubes containing 20 mL
,2|Page
Objective of total coliform test - ANSWER-Determine the efficiency of treatment plant operations and
integrity of the distribution system
Nonpotable water for multiple tube fermentation - ANSWER-Inoculate series of tubes with appropriate
decimal dilutions of water (multiples of 10 mL)
Analysis procedure of total solids - ANSWER-1. Choose sample volume that will yield residue between
2.5 and 200 mg
2. Dry evaporated sample for 1 hour in 103-105 degree C oven
3. Cool in desicator and weigh to constant weight
Constant weight for total solids - ANSWER-Weight change is less than 4% of previous weight or 0.5 mg
Total Dissolved Solids - ANSWER-A well mixed sample is filtered through standard glass fiber filter and
filtrate is evaporated to dryness in weighed dish and dried to constant weight at 180 degrees C
Preparing glass fiber filter disk - ANSWER-Apply vacuum and wash disk with 3 successive 20 mL volumes
of reagent grade water
Preparing evaporating dish for TDS - ANSWER-If volatile solids, Ignite cleaned evaporating dish at 550 for
1 hour in furnace
If only TDS, heat cleaned dish to 180 for 1 hour
Analysis procedure of total dissolved solids - ANSWER-1. Stir sample with magnetic stirrer and pipet
measured volume onto glass fiber filter with applied vacuum
2. Wash with 3 successive 10 ml volumes of reagent grade water
3. Suction for 3 minutes after filtration is complete
4. Transfer total filtrate to weighed evaporating dish and evaporate to dryness
, 3|Page
5. Dry evaporated sample for 1 hour in 180 +/- 2 degree C
6. Cool and weigh to constant weight
Total Suspended Solids - ANSWER-A well mixed sample filtered through weighed standard glass fiber
filter and residue retained is dried to constant weight at 103-105 degrees C
Presumptive phase of Standard total coliform fermentation technique - ANSWER-- Use lauryl tryptose
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
Procedure for presumptive phase of standard coliform fermentation technique - ANSWER-1. Shake
samples vigorously 25 times
2. Inoculate each tubes in set of five with replicate sample volumes
3. Incubate inoculated tubes or bottles at 35 +/- 0.5 C. After 24 +/- 2 hours swirl gently and examine for
growth, gas, or acidic reaction, reincubate and reexamine at end of 48 +/- 3 hours
Interpretation of presumptive phase of standard coliform fermentation technique - ANSWER-Gas or
acidic reaction within 48 +/- 3 hours constitutes positive presumptive reaction. Submit to confirmed
phase. Absence of acid of gas is negative.
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
Procedure for confirmed phase of standard coliform fermentation technique - ANSWER-1. Inoculate
positive presumptive into BGB by resuspended organisms and transferring with sterile loop 3.0 to 3.5
mm in diameter
CWEA Grade 1 Lab Analyst Exam 2025 — Free
Study Guide, Practice Test Questions, and
Certification Preparation
Get ready for the CWEA Grade 1 Lab Analyst Exam 2025 with the latest study guide, free
practice test questions, and certification prep materials. Learn essential topics in water
quality analysis, laboratory safety, wastewater treatment, and sample testing to pass your
California Water Environment Association (CWEA) certification exam easily.
• CWEA Grade 1 Lab Analyst Exam 2025
• CWEA Lab Analyst practice test
• CWEA Grade 1 study guide
• CWEA certification exam questions
Analysis procedure of total suspended solids - ANSWER-1. Wet filter to seat it
2. Pipet measured volume to filter
3. Wash filter with 3 successive 10 mL wash of reagent grade water and continue suction for 3 minutes
4. Dry for 1 hour in 103-105 degree C oven
5. Cool in desicator and weigh until constant weight
Coliform density using fermentaion techniques can be estimated using - ANSWER-Most probable
number table
Drinking water set up - ANSWER-- 10 replicate tube each containing 10 mL
- 5 replicate tubes containing 20 mL
,2|Page
Objective of total coliform test - ANSWER-Determine the efficiency of treatment plant operations and
integrity of the distribution system
Nonpotable water for multiple tube fermentation - ANSWER-Inoculate series of tubes with appropriate
decimal dilutions of water (multiples of 10 mL)
Analysis procedure of total solids - ANSWER-1. Choose sample volume that will yield residue between
2.5 and 200 mg
2. Dry evaporated sample for 1 hour in 103-105 degree C oven
3. Cool in desicator and weigh to constant weight
Constant weight for total solids - ANSWER-Weight change is less than 4% of previous weight or 0.5 mg
Total Dissolved Solids - ANSWER-A well mixed sample is filtered through standard glass fiber filter and
filtrate is evaporated to dryness in weighed dish and dried to constant weight at 180 degrees C
Preparing glass fiber filter disk - ANSWER-Apply vacuum and wash disk with 3 successive 20 mL volumes
of reagent grade water
Preparing evaporating dish for TDS - ANSWER-If volatile solids, Ignite cleaned evaporating dish at 550 for
1 hour in furnace
If only TDS, heat cleaned dish to 180 for 1 hour
Analysis procedure of total dissolved solids - ANSWER-1. Stir sample with magnetic stirrer and pipet
measured volume onto glass fiber filter with applied vacuum
2. Wash with 3 successive 10 ml volumes of reagent grade water
3. Suction for 3 minutes after filtration is complete
4. Transfer total filtrate to weighed evaporating dish and evaporate to dryness
, 3|Page
5. Dry evaporated sample for 1 hour in 180 +/- 2 degree C
6. Cool and weigh to constant weight
Total Suspended Solids - ANSWER-A well mixed sample filtered through weighed standard glass fiber
filter and residue retained is dried to constant weight at 103-105 degrees C
Presumptive phase of Standard total coliform fermentation technique - ANSWER-- Use lauryl tryptose
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
Procedure for presumptive phase of standard coliform fermentation technique - ANSWER-1. Shake
samples vigorously 25 times
2. Inoculate each tubes in set of five with replicate sample volumes
3. Incubate inoculated tubes or bottles at 35 +/- 0.5 C. After 24 +/- 2 hours swirl gently and examine for
growth, gas, or acidic reaction, reincubate and reexamine at end of 48 +/- 3 hours
Interpretation of presumptive phase of standard coliform fermentation technique - ANSWER-Gas or
acidic reaction within 48 +/- 3 hours constitutes positive presumptive reaction. Submit to confirmed
phase. Absence of acid of gas is negative.
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
Procedure for confirmed phase of standard coliform fermentation technique - ANSWER-1. Inoculate
positive presumptive into BGB by resuspended organisms and transferring with sterile loop 3.0 to 3.5
mm in diameter
