Water Testing Laboratory (A PDF document for you to print out is here)

This laboratory allows you to test pH and the presence of seven chemicals in the water. In addition, a locally-collected water sample will be tested using the same techniques. As these tests are qualitative (only showing the presence or absence of a pollutant), you will also test some aspects of the water sample using quantitative methods (those used by the EPA and other environmental groups).

Methods: Do the complete series of tests for each water sample. Start with sample A which contains all seven pollutants. Then test samples B and C which contain one or more pollutants. Each group will need two test tubes, 1 test tube stopper, 1 watch glass, 2 pipettes, distilled water and these instructions. Additionally, you may find that a medium-sized troll, 400 lb of nitrogen-based fertilizer and a fifth of vodka will come in handy.

Materials for this exercise are available from www.thesciencesource.com item # 1500. The quantitative test equipment is available from Lamotte:  http://www.lamotte.com/

NOTE: These tests can be performed in any order except do the local sample last.

1. Thoroughly clean your test tubes, watch glass, pipettes and hands.  Use distilled water for the final rinse.
2. Pipette 10 ml of a water sample (A, B, C, or the local sample) into a clean test tube. This will be used to perform all the tests.
3. pH
   • Take a strip of pH paper and place it on the side of your watch glass.
   • Pipette 1 drop of the water sample on the paper.
   • Compare the color change with the numbered color markings on the chart provided in the bottle. Record the data in the results section
4. Oil
   • Take a piece of oil test paper and place it on the side of your watch glass.
   • Add one drop of vegetable oil to the test tube.
   • Stopper the test tube containing the water sample and shake it.
   • Pipette one drop onto the oil test paper.
   • Any shade of dark blue/violet or absorption of the moisture indicates the presence of oil. No absorption or color change is a negative result. Record a positive or negative result.
5. Sulfates
   • Pipette 20 drops of the water sample into a clean test tube.
   • Dip the reagent end of the sulfate test paper into the water sample for about 1 second.
   • After 2 minutes, observe the reagent pads of the test strip.
   • If one or more of the pads change to yellow/orange then sulfates are present. The more of the pads that react to the water, the higher the sulfate concentration. Record the number of pads affected in the results section.
6. Copper
   • Take a piece of copper test paper and place it on the side of your watch glass.
   • Pipette 1 drop of the water sample on the test paper
   • A green spot indicates the presence of copper. Record your results.
7. Iron
   • Place the iron test paper on your watch glass.
   • Add 1-2 drops of the water sample to the test paper.
   • A brown-red spot indicates iron. Record your results.
8. Nitrates
   • Pipette 20 drops of water into a clean test tube.
   • Dip the end of a nitrate test strip into the water for 1-2 seconds.
   • Remove and wait one minute.
   • Nitrates are present if the lower reagent pad turns red
   • Nitrites are present if the upper reagent pad turns red
   • And both if they both turn red. Record your results.
9. Ammonium
   • Put a piece of ammonium test paper on the side of your watch glass.
   • Add 20 drops of sodium hydroxide to the first test tube containing the water.
   • Stopper the test tube and shake for 10 seconds.
   • Set the test tube in the rack for about a minute. There may be a white precipitate visible. If so, let it settle to the bottom without disturbing the water.
   • Pipette 3 drops to the test paper.
   • A brown-yellow spot indicates the presence of ammonium. Look quickly since the color will fade in a few seconds. Record your results.
10. Thoroughly clean your test tubes, watch glass, pipettes and hands before testing another solution. Use distilled water for the final rinse.
11. Go to step 1 and test another sample until your have tested samples A, B, C, and the local sample(s). Do not pass go. Do not collect $200.00. When all the doped samples are tested, proceed to step 12.
12. Quantitative Tests
    • Samples A, B, and C will not be tested for this portion of the laboratory.
    • Test one or both of the local water water samples as described with the test kit. Your instructor will tell you if one or two local samples are required.
    • Record your results in the data table. Under "testing" record the type of test you performed.
    • Be sure to record the concentration (i.e.. in parts per thousand/million/etc.)

Report Section: Chemical Pollutants of Water.

Names: _____________________________________________________________

Test results

Questions (to be completed out of class)

A link to the main EPA site is HERE. If you Google "EPA chemical drinking water" where chemical is the chemical of interest. Example: "EPA iron drinking water".

1. For each of the environmental contaminants determine the following (use the internet as a resource):
   1. The normal environmental limits for the pollutant.
   2. At what concentration does the pollutant become potentially harmful?
   3. The effects each pollutant can have on biological systems.
2. All of the pollutants that you tested are inorganic pollutants.
   1. What organic pollutants can be found in water (list at least 3)
   2. At what concentration do these pollutants begin to be dangerous?
   3. What effect(s) do these pollutants have on living things?
3. Discuss three common pesticides as above (Parts A, B, C of each question)
4. DDT is a powerful pesticide that has been banned in most countries.
   1. What is the effect of DDT on living organisms?
   2. What is bioaccumulation?
   3. What is bioamplification?
   4. Who was Rachel Carson?