How Well Does Your Water Filter Work? Experiment For Kids At Home.

Whether you have well water or municipal water, you can never be too certain about what is in your water.  Many people choose to use a water filter to ensure that their water is safe to drink, but how do you know if your water filter is working?  The best way to know what is in your water is to test it using Test Assured’s 4 Test Kit Set for Schools and Science Fairs. This set includes 4 test kits and is appropriate for children in grades three through twelve.

In this experiment, we will be testing unfiltered water, water purified with an old filter, and water purified with a new filter.  Our results were not what we had expected.  Gather your supplies and let’s see how your water filter is working compared to ours.

Supplies

The first thing you need to do is gather your supplies:

  • Test Assured 4 Test Kit Set with TD Meter
  • Tap water
  • Water filtration system that is currently in use
  • Replacement water filter
  • Zipper sandwich bags
  • Paper towels

 

Test Assure 4 Test Kit with TDS Meter

 

We used a PUR water filtration system.  We took water samples before and after changing the filter.

 

Preparation

To prepare for the tests, you’ll need to gather your water samples.  For this experiment, you need three samples:

  1. Tap water for your control
  2. Tap water passed through a used filter
  3. Tap water passed through a new filter

We found that one of the easiest ways to handle water samples is to use zipper sandwich bags.  You can easily label the bags, and they are large enough to allow for the TDS test.  For more stability (and less chance of spills) you can put the baggies inside mugs or cups.

We started with our water samples in zippered sandwich bags.

Now is a good time to label your vials and write your water sources in the results notebook.

Testing

The first test you want to start with is for total dissolved solids, using the TDS meter.  The meter will not fit in the test vials, so it is easier to complete this part of the experiment while your samples are still in the baggies.  To perform the TDS test, simply turn on the meter and submerge the prongs in the samples. Rinse the meter with clean water between each test. Record your results in the results notebook.

We placed the meter directly in the baggie to get a reading for total dissolved solids.

After completing the TDS test, you will need to pour your samples into the vials you labeled.  To transfer your samples to the vials, simply snip off a small corner of the baggie to create a spout. Fill each vial to within a ¼” of the top.  Be sure to wipe up any spills, so you don’t contaminate the test strips.

Cut off a corner of the baggie to create a spout to easily transfer your samples to the vials.

Before you get started with the tests, now is a good time to make some visual observations. Take notes about how clear or cloudy your samples look.  Are there any visible particles floating in any of the samples?  These observations can be written in the “Notes” on the last page of the results notebook.

Now you’re ready to get started with the rest of the tests. It’s best to work with one sample at a time.  Follow these instructions to complete the remaining tests.

Alkalinity/pH/Hardness Test

  1. Remove the test strip from the packet labeled, “ALK/pH/Hard”
  2. Pick up the strip on the end with no pads
  3. Dip the strip in the sample for one second and remove
  4. Hold the test strip level and wait 10 seconds
  5. Place the strip as shown in the picture and compare to the color chart for alkalinity, pH, and hardness
  6. Record your results in the results notebook

Place the strip as shown for the Alkalinity/pH/Hardness Test

Total Chlorine/Copper/Nitrate/Nitrite Test

  1. Remove the test strip from the packet labeled, “CL/CO/NA/NI”
  2. Pick up the strip on the end with no pads
  3. Dip the strip in the sample three times and remove – DO NOT SHAKE OFF EXCESS WATER
  4. Hold the test strip level for 2 seconds
  5. Place the strip as shown in the picture and compare to the color chart for chlorine and copper
  6. Wait 45 seconds before reading the results for nitrate and nitrite
  7. Record your results in the results notebook

Place the strip as shown for the Chlorine/Copper/Nitrate/Nitrite Test

Iron Test (Complete this test last)

  1. Remove one iron reagent tablet from the foil packet and place in test vial (the reagent could alter the results of other tests which is why the iron test is completed last)
  2. Place the cap on the test vial and shake for approximately one minute, until the tablet is completely dissolved
  3. Remove the test strip from the packet labeled, “Iron Test”
  4. Dip the strip in the sample for 2 seconds
  5. Shake the strip once and wait 60 seconds
  6. Place the strip as shown in the picture and compare to the color chart for iron
  7. Record your results in the results notebook

Place the strip as shown for the Iron Test

Repeat all three tests for each of your samples.

Results

Now that you have completed each of the four tests on your three samples, it’s time to look at your results.  Ask yourself these questions:

  • How does the water filter alter the composition of the tap water?
  • What was the difference between the old filter and the new filter?
  • Does your tap water meet the EPA recommended levels for drinking water? (These are listed in the Guide & Results Notebook.)
  • What results did you find the most surprising?

Record your answers on the “Notes” page.  If you are using this as a science fair project, you can use clear tape to fix the test sticks to the color charts to display your results.

We were surprised to find that our used water filter performed better than our new water filter.  Some companies recommend that you run a few gallons of water through a new filter before using. The filter we tested did not include that in the instructions, but we’ll be testing the water again to see if that makes a difference.

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