After I collected several samples of filtered tap water, I started the titrations.  To titrate each sample, I pipeted 50.0 mL of each sample into two aliquots.  I added 4.0 mL of the ammonia-ammonium chloride buffer solution to each aliquots.  Then, I added about 8 drops of Calmagite indicator to each and titrated with the EDTA solution to the point where the color of the sample changed from burgundy to blue.  If the volume of EDTA used in the two aliquots had significant variation, I titrated a third sample.


After each sample was titrated, the grams of CaCO₃ for each was calculated by the using the following equation:
volume of EDTA used x ^{0.00460 mol EDTA}/1000 mL  x  ^{1 mol CaCO3}/1 mol EDTA 
x  ^{100.09g CaCO3}/1 mol CaCO3  =  grams of CaCO₃


After the grams of CaCO₃ was determined, I found the parts per million (ppm) of CaCO₃ in each sample by using the following equation:
^{Grams CaCO3}/50.0 g H₂O x  10⁶ = ppm CaCO₃


The grams of CaCO₃ and ppm CaCO₃ were then put on a graph in order to see the relationship between the amount of filtered water and the effectiveness of the filter (see Filter Record).