CMA ACTUAL EXAM QUESTIONS AND
COMPLETE STUDY GUIDE 2026
▶ Why should wet and dry TS samples be weighed quickly? Answer: -Wet
samples lose moisture through evaporation
-Dry samples will gain moisture once removed from the desiccator
▶ What is the oven temp for VS determination? Answer: 500C +/- 50 until
steady weight
▶ VS can only be done on a sample after Answer: TS determination
▶ VS Calculation Answer: %VS = (dry+dish - ashed+dish)*100 / (dried
sample)
%VS=
(A-D)*100/(A-B)
A:weight of dried sample + dish(mg)
B=weight of dish (mg)
D=weight of ashed sample + dish (mg)
▶ How is TSS measured? Answer: A known volume of sample is put
through a dried and weighed filter, then dried.
The increase in weight of the filter represents the suspended solids.
▶ TSS calculation Answer: TSS (mg/L) = (dried sample)*1000 / mL sample
TSS (mg/L) =
(A-B)*1000 / V
A:weight of filter +dried residue (mg)
B:weight of filter (mg)
V: volume of sample (mL)
, ▶ How much sample should be poured for TSS? Answer: *Only up to 1L
*2mg-200mg of residue
-2mg: too little difference in weight
+200mg: may not completely dry
▶ How is TSS & VSS & TDS reported? Answer: mg/L
▶ VSS Calculation Answer: The weight lost is the VSS
VSS (mg/L) =
(A-B)*1000/V
A:weight of dried filter + residue (mg)
B: weight of ashed filter + residue (mg)
V: volume of sample (mL)
▶ How is TDS measured? Answer: A known volume of sample if filtered
into a crucible. The crucible is dried and weighed. The increase in weight
represents the dissolved solids in the sample.
▶ What temperature is used to dry TDS? Answer: 180+/-2 C
▶ How much residual is needed for TDS? Answer: 10-200mg
If sample volume of 10mg residual is too high to fit in the crucible, add
successive aliquots of sample to crucible after drying.
▶ TDS Calculation Answer: The increase in weight of the crucible is the
TDS
TDS (mg/L) = (dried sample * 1000) / mL sample
TDS (mg/L) =
(A-B)*1000/V
A: weight of dried residue + dish (mg)
B:weight of dish (mg)
▶ Settleable Solids Answer: Solids that will settle out of the water sample
COMPLETE STUDY GUIDE 2026
▶ Why should wet and dry TS samples be weighed quickly? Answer: -Wet
samples lose moisture through evaporation
-Dry samples will gain moisture once removed from the desiccator
▶ What is the oven temp for VS determination? Answer: 500C +/- 50 until
steady weight
▶ VS can only be done on a sample after Answer: TS determination
▶ VS Calculation Answer: %VS = (dry+dish - ashed+dish)*100 / (dried
sample)
%VS=
(A-D)*100/(A-B)
A:weight of dried sample + dish(mg)
B=weight of dish (mg)
D=weight of ashed sample + dish (mg)
▶ How is TSS measured? Answer: A known volume of sample is put
through a dried and weighed filter, then dried.
The increase in weight of the filter represents the suspended solids.
▶ TSS calculation Answer: TSS (mg/L) = (dried sample)*1000 / mL sample
TSS (mg/L) =
(A-B)*1000 / V
A:weight of filter +dried residue (mg)
B:weight of filter (mg)
V: volume of sample (mL)
, ▶ How much sample should be poured for TSS? Answer: *Only up to 1L
*2mg-200mg of residue
-2mg: too little difference in weight
+200mg: may not completely dry
▶ How is TSS & VSS & TDS reported? Answer: mg/L
▶ VSS Calculation Answer: The weight lost is the VSS
VSS (mg/L) =
(A-B)*1000/V
A:weight of dried filter + residue (mg)
B: weight of ashed filter + residue (mg)
V: volume of sample (mL)
▶ How is TDS measured? Answer: A known volume of sample if filtered
into a crucible. The crucible is dried and weighed. The increase in weight
represents the dissolved solids in the sample.
▶ What temperature is used to dry TDS? Answer: 180+/-2 C
▶ How much residual is needed for TDS? Answer: 10-200mg
If sample volume of 10mg residual is too high to fit in the crucible, add
successive aliquots of sample to crucible after drying.
▶ TDS Calculation Answer: The increase in weight of the crucible is the
TDS
TDS (mg/L) = (dried sample * 1000) / mL sample
TDS (mg/L) =
(A-B)*1000/V
A: weight of dried residue + dish (mg)
B:weight of dish (mg)
▶ Settleable Solids Answer: Solids that will settle out of the water sample
