Upper school biology students use the sun to make clean water


Biology students prepared for the worst this month, creating solar stills—environmentally friendly systems that use the sun’s energy to convert saltwater into purified water through condensation. 

Upper school science teacher Alan Stell was thrilled to introduce the project to his ninth graders.

“We started the project by discussing how important water is to living things. We can only go about three days without water,” said Stell. “Hurricane Dorian had just hit the Bahamas, so it was timely that we talk about the abundance of sea water after a hurricane strikes. The students researched solar stills and choose a design they liked and wanted to construct out of materials most likely to be found after a hurricane. It was a great engineering problem.” 

Student groups took their projects outside to harness energy from the sun to amass fresh water. Twenty four hours later, the groups anxiously checked their creations for drinkable water. Students soon learned they needed to account for things like evaporation, unpredictable weather conditions and whether or not the materials they’d used were water tight. 

“The goal was to collect about 250 mL of freshwater, but the most anyone got was about 30 mL—barely a swallow’s worth,” said Stell. “I think going from a design to an idea to actually building a solar still was harder than most students imagined. For that reason, it was a great lesson!”


Groups brought their projects inside to test for the water’s conductivity. If the water was highly conductive, it was saltwater, and they learned they hadn’t sealed their projects correctly. If the water was not conductive, they knew they had clean drinking water! The lower the conductivity level, the purer the water. 

Ivy Poole ’22 thought the project was a great way to make real-world connections. “I didn’t know I could purify water through condensation,” she said. “I made my project entirely out of recycled plastic. I volunteer at the Red Cross, and they do a lot of hurricane relief, so I thought it was a really cool project.”