The Rainforest Washstand Pump Challenge

Water for a Rainforest Washstand

At a rainforest field station, workers rinse muddy equipment in a wash basin. A student engineering team builds a tabletop model that moves clean water from a bucket into the basin. In each 30-second trial, the device must deliver at least 200 milliliters (mL) into the basin and spill no more than 10 mL outside it. Faster delivery is useful, but both limits matter.

The team uses a battery pack, a switch, insulated connecting wires, an enclosed low-voltage pump, and flexible tubing. The battery supplies electrical energy. Inside the pump, electrical energy makes a small part spin. That moving part pushes water through the tube. An outlet attachment at the tube's end directs the water toward the basin.

First, the teacher checks the equipment and sets the basin 20 centimeters above the bucket's starting water level. Students use clean, room-temperature water. The battery pack, switch, and connections stay on a dry tray away from splashes. The teacher handles the pump and connections. Students do not open the pump or use wall outlets.

Next, the team compares three outlet attachments. Design A has a narrow spout. Design B has a wide spout. Design C has the same wide spout plus a smooth guide that directs water downward. The attachment is the feature changed between designs. The team keeps the same pump, tubing length, basin position, and starting water level. The teacher provides the same starting battery condition.

The team runs each design three times for 30 seconds per trial. After each trial, students measure the water collected inside the basin. They also measure water caught on a waterproof tray outside the basin. They empty the basin and reset the water level before starting again.

Finally, students record what happens when the switch is opened and closed. With the switch closed, the pump runs and pushes water into the tube. Opening the switch stops the electrical supply; the pump stops, and water delivery ends after the tube finishes draining. Closing the switch starts the pump and water delivery again.