Not all purification methods remove the same contaminants. Distillation heats water into steam and collects it, leaving most dissolved chemicals and bacteria behind. Filtration pushes water through a barrier that traps particles. Solar pasteurization uses sunlight to heat water enough to kill germs — but it does not remove dissolved chemicals. When you test all three against tap water, Chicago River water, and E. coli B bacteria across eight contaminants, the differences become clear: distillation removes the most and kills the most bacteria, filtration is fastest and cheapest, and solar pasteurization ranks last in three of four categories.

Ammonia is a strong-smelling gas made of nitrogen and hydrogen that forms when organic waste breaks down in water. It is one of eight contaminants tested when comparing filtration, distillation, and solar pasteurization across tap water and Chicago River water. Distillation heats water into steam and collects it, and that process proved most effective at removing contaminants including ammonia nitrogen from both sources.

Coliform bacteria like E. coli are common germs that signal dirty water, but testing for them also reveals how well purification works. Here, E. coli B bacteria are added to sterile water, and each purification method is then tested for its ability to kill them. The results show which method best eliminates these indicator germs from a water supply.

Distillation works by boiling water into steam and cooling that steam back into liquid, leaving contaminants behind. When tap water and river water samples went through distillation, filtration, and solar pasteurization head to head, distillation removed the most contaminants of the three methods.