Analysis of Bottled Water
V. Total Dissolved Solids (TDS) – Form E
Total dissolved solids (TDS) is the measure of the total amount of all the materials that are dissolved in water. These materials, both natural and anthropogenic (made by humans), are mainly inorganic solids, with a minor amount of organic material. TDS are compounds in water that cannot be removed by a traditional filter. TDS are made up of salts or compounds which dissociate in water to form ions. TDS can give water a murky appearance and detract from the taste quality of the water. The U.S. Environmental Protection Agency's (EPA) Secondary Drinking Water Standards recommends that the TDS concentrations in drinking water not exceed 0.05% (500 mg/L), based on taste and aesthetics.
Sources:
http://waterquality.montana.edu/docs/homeowners/tds_fact_sheet.shtml
http://www.eerc.und.nodak.edu/watman/FMRiver/PPTV/totaldissolvedsolids.asp
http://www.freedrinkingwater.com/water-education2/72-tds-water.htm
http://www.idph.state.il.us/envhealth/pdf/DrinkingWater.pdf
Procedure:
· Obtain three 50 mL beakers
o Label each beaker with numbers and your initials
o Weigh and record the mass of each beaker to the nearest milligram (0.001 g)
· Measure 20 mL of water sample, using a graduated cylinder, and add to each beaker
· Place beakers on a hot plate
o Adjust so the water will boil gently
o Heat until the water has completely evaporated
· Remove beakers using tongs and allow to cool
o Check to make sure that the beakers are totally dry with no hint of moisture
· Reweigh and record the mass of each beaker
· Calculate the average TDS and record your data below
·
Transfer all your data to the class data sheet - Form F
Water Samples
|
Sample 1: |
Trial 1 |
Trial 2 |
Trial 3 |
Average TDS |
|
Volume of water used (mL) |
|
|
|
|
|
Mass of beaker (g) |
|
|
|
|
|
Mass of beaker + solid (g) |
|
|
|
|
|
Mass of solid (g) |
|
|
|
|
|
TDS (mg/L) or (ppm) |
|
|
|
|
|
Sample 2: |
Trial 1 |
Trial 2 |
Trial 3 |
Average TDS |
|
Volume of water used (mL) |
|
|
|
|
|
Mass of beaker (g) |
|
|
|
|
|
Mass of beaker + solid (g) |
|
|
|
|
|
Mass of solid (g) |
|
|
|
|
|
TDS (mg/L) or (ppm) |
|
|
|
|
|
Sample 3: |
Trial 1 |
Trial 2 |
Trial 3 |
Average TDS |
|
Volume of water used (mL) |
|
|
|
|
|
Mass of beaker (g) |
|
|
|
|
|
Mass of beaker + solid (g) |
|
|
|
|
|
Mass of solid (g) |
|
|
|
|
|
TDS (mg/L) or (ppm) |
|
|
|
|
|
Sample 4: |
Trial 1 |
Trial 2 |
Trial 3 |
Average TDS |
|
Volume of water used (mL) |
|
|
|
|
|
Mass of beaker (g) |
|
|
|
|
|
Mass of beaker + solid (g) |
|
|
|
|
|
Mass of solid (g) |
|
|
|
|
|
TDS (mg/L) or (ppm) |
|
|
|
|
ppm of TDS = (mass of solid (g)) x (1,000 mg/1 g) ÷ (volume of water (L))
TDS Data
|
Type and Brand of water |
TDS (ppm) |
|
|
|
|
|
|
|
|
|
|
|
|
Levels of TDS (ppm)
|
Less than 500 |
Satisfactory |
|
500-1,000 |
Less than desirable |
|
1,00-1,500 |
Undesirable |
|
Over 1,500 |
Unsatisfactory |
Questions