Which water purification method removes the most contaminants? This project puts three methods head to head: filtration vs. distillation vs. solar pasteurization. You test tap water and Chicago River water for eight contaminants: - pH - Chlorine - Hardness - Nitrate - Phosphate - Ammonia nitrogen - Copper - Iron You run each water sample through all three purification methods. Then you retest and compare. You also introduce E. coli B bacteria into sterile water and test each method's ability to kill it. Distillation removed the most contaminants and killed the most bacteria. Filtration was fastest and cheapest. Solar pasteurization ranked last in three of four categories.