Water purification refers to a variety of techniques for removing dirt, debris and chemical residue from water. This is a topic which lends itself easily to science fair projects, experiments and in-class activities. Students can gain hands-on experience and observe science in action with a variety of projects that can be modified to suit a wide range of grade levels.
Students conduct a series of experiments to determine the best way to filter water. Initially, students mix sand or dirt with water to create a dirty water sample. Then the children experiment with a variety of different materials (for example, coffee filters, paper towel, an old t-shirt, and toilet paper). Students pour the dirty water through the filter into glasses, and determine which filter worked best by identifying the cleanest water sample. This experiment could also use a variety of natural materials such as sand, charcoal, gravel and wood chips for comparison as filters.
Water Quality Comparison
Using water test strips readily available at retail stores and online retailers, students test a variety of water sources for PH value, chlorine, alkalinity, hardness, nitrates and nitrites. Students assess whether bottled water really is superior to tap water filtered at home through a pitcher style filter. An alternative angle on this project would be to identify differences between ocean, lake, tap and bottled water.
Condensation and Evaporation
Students observe how the naturally occurring processes of evaporation and condensation work to purify water. Children mix a bowl of water with dirt or sand. Placing an empty glass in the center of the bowl, students cover the entire bowl and glass with clingwrap. Students place a cover or rock on top of the glass, then place the bowl and glass outdoors or in a window directly in natural sunlight for a few hours. Children should discover that the glass ultimately contains fairly clean water and the bowl contains the dirt or sand.
Environmental Community Project
Water purification projects can be a way to get students involved in the local community, introducing them to environmental activism and water conservation efforts. After researching water use at their school and talking to local experts, students can identify a community project. Potential projects might include reducing the amount of water pollutants introduced into the water supply by janitorial staff and car wash fund raising events, making posters or developing a skit to highlight the effects of disposing hazardous waste into the water stream, or researching environmentally friendly alternatives to cleaning materials or other pollutants identified at the school.