Narrator: : This is Science Today. In many areas of the country, drinking water comes from groundwater. As ecologist Alex Horne of the University of California, Berkeley points out, groundwater has some pretty unsavory components.

Horne: In a lot of cases we have a mixture of wastewater, which was once human waste, we have agricultural runoff, which was either cattle waste or fertilizer, and we have what we call nuisance runoff -- the runoff from golf courses and from irrigation in parks and landscaped areas -- sinking into the ground, and then we have to do something with it.

Narrator: : But in a series of experiments near Los Angeles, Horne has discovered that diverting the water through an artificial wetland -- an area of shallow water with reeds and vegetation -- cleans it up as well as or better than more high-tech methods. And wetlands have other benefits.

Horne: I can do multiple uses, I can get multiple benefits. I can get treatment of waste, I can get a source of clean water, and I can grow organisms that we would desire -- birds and plants and so on. I can provide refuges for living organisms.

Narrator: : For Science Today, I'm Steve Tokar.