Safe or Not? Students Use the Scientific Method to Test Water in the Village of Cuba

Written by the Students of Cuba Middle School

During its effort to promote drinking water for health, the Step Into Cuba team heard many Cuba-area residents say that the water there doesn’t taste good. But is the water safe? In the light of recent events in Flint, Michigan, students at Cuba Middle School wanted to find out.

 Sixth-, seventh-, and eighth-grade students tested several water samples in their science lab. The samples were tap water from science teacher Ms. Daisy Cortez’s home, water from a regular school fountain, water from a newly installed Brita “hydration station” at school, bottled water, and pond water collected near Rito San Jose. The students tested each sample for pH, alkalinity, hardness, nitrates, nitrites, chlorine, total dissolved solids (TDS), total dissolved metals (TDM), and bacterial growth.

Because there are six different science-class periods at Cuba Middle School, each sample was tested six times. Repetition is an important principle in science: it reduces the risk of drawing conclusions based on accidental or incorrect data. For example, if a scientist forgot to wash his or her hands after petting a dog and then tested a water sample for bacteria, the scientist might contaminate the sample. The results of the test would then be inaccurate, that is, the level of bacteria in the sample would appear to be much higher than what was actually in the water.

 The students found that the water from Ms. Cortez’s home, the water from the regular school fountain, and the water from the Brita fountain were all safe. However, the water from Ms. Cortez’s home was very hard. Hard water is safe to drink; it just has some extra magnesium and calcium in it. Because of the geologic features of the Cuba area, the water there is particularly hard. The water from the regular school fountain and the Brita fountain was much less hard, even though the Village of Cuba’s water is the source of the water at all three of these test sites. This is because Cuba Independent School District has a large water softener for its campus. The bottled water had a surprisingly low pH of 4.5. A low pH is not necessarily unsafe: soda, coffee, and orange juice are all technically acids, or have a low pH. However, the Environmental Protection Agency (EPA) recommends that drinking water’s pH be between 6.5 and 8.5.

 Students were surprised that the murky pond water was “safe” with respect to pH, alkalinity, nitrates, nitrites, chlorine, TDS, and TDM. However, when they received the bacterial-growth results, they saw scientific evidence for why one wouldn’t want to drink pond water.

 Aside from the pond water, all the water tested was safe to drink. The students encourage Cuba-area residents to drink water! It is important to drink water so that you stay hydrated, which will help you stay healthy and energetic. If you don’t like the taste of the water, students suggest that you filter it (like in the Brita fountains at school) to remove some of the minerals. Students also recommend adding tea bags (without sugar), a little bit of juice, or some fruit to give the water flavor.

 This article was composed by compiling student statements and passages from students’ lab notebooks. The Science Education Partnership Award thanks Ms. Daisy Cortez and her students for using science as a tool in their community. We hope their results will increase Cuba residents’ confidence in water as the healthy choice