Prepare beakers or glasses by pouring 200mL distilled water in the first, 1 Tbsp. salt in the second, 1 Tbsp. sugar in the third, 100mL white vinegar in the fourth and 3 drops dishwashing liquid to the last container. Add distilled water to each in order to bring contents to a total volume of 200mL.
Stir salt and sugar in the water until they dissolve. Gently swirl vinegar and detergent to mix without producing soap bubbles in the final beaker.
Provide 10 strips of litmus paper to each student and discuss the pH scale. Explain how to read litmus strips after testing each water sample.
Instruct students to insert a litmus strip in each beaker and record the results in their lab journals.
Boil each sample for 10 minutes. Rinse out all beakers and return contents to their original containers.
Repeat the litmus tests and record results. Compare data from the first and second tests and discuss whether boiling water is always an effective method of killing contaminants for sanitation.