Lester J. Rosario Workshop: Water sampling, testing, and statistical application By Dr. Javier Arce Water plays an important role in a human’s metabolism. Since humans have todrink water, it is very important to keep it free from microorganisms and other substancesthat may have adverse effects on health. This workshop offered good information about theprocess that water has to pass through in order to make it suitable for drinking in ourhomes. I learned that water quality depends on the country, and that there are someenvironmental and human variables that affect water quality. Environmental variablesinclude: animals, soil composition, forests, and climate. Examples of human variables are:agriculture (fertilizers containing toxics), urban areas, and the management of residuals. Toanalyze water samples, a especial procedure is needed. It begins with the technique forobtaining water samples from tap water in different areas, then, the samples are examinedfor the presence of E. coli and total coli forms. Later, Excel is used to arrive at statisticalcalculations such as averages, standard deviations, and lineal regression, and to plot graphsof the results of the different water samples. In conclusion, I learned that water sourcesfound in densely populated areas have more presence of E. coli (fecal coli forms) thanwater sources found in unpopulated areas.