Coliform bacteria are germs found in animal waste that signal dirty water. When wells sit near livestock pens, fecal bacteria like E. coli can travel through soil and reach groundwater — sometimes moving surprisingly far from the source. In this experiment, wells near animal pens tested positive for coliforms, while wells farther away showed no contamination at all.

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.

Coliform bacteria are common germs found in soil and water, and how far they travel through soil determines whether groundwater stays clean. In this experiment, a laboratory strain of E. coli flows through packed columns of Hawaiian agricultural soil to measure how far these bacteria move. As the organisms either pass through or get trapped, the results reveal how soil structure alone can block coliform contamination from reaching the water below.