Reclaiming Wastewater through Soil Aquifer Treatment

Greater Harmony Between Agriculture and the Environment
Research Year: 

Water-short areas in the U.S. and around the world have turned to reclaiming wastewater as a way to increase water supplies. Some treatment methods use chemical additives to help purify the water. Charles Gerba, a University of Arizona soil scientist, tested a more natural method currently used in Tucson, and found that it produced high quality nonpotable water without additives at a low cost.

Description of Action: 

The soil aquifer treatment used a 37-meter layer of soil as a filter. Wastewater was purified as it passed through, and was then collected in underground storage tanks. This is a natural, sustainable system that will not wear out. It takes the place of building a conventional treatment plant


The soil aquifer treatment significantly reduced enteroviruses as they passed through the soil. Groundwater samples held no Giardia. The two organic compounds present were reduced by 92 percent and 85 percent respectively, and total nitrogen leached out 47 percent during recharge. The project has now expanded to include the City of Phoenix in Arizona, and Los Angeles and Orange Counties in California, at the request of those communities.

In Tucson, the project grew to include studies on using artificial wetlands as a pretreatment before soil aquifer treatment. At Tucson’s Sweetwater Wetland and Recharge Facility the wetlands method reduced Giardia cysts and Cryptosporidium oocysts by more than 99.9 percent, and fecal coliforms and coliphages by 68 and 52 percent, respectively.

Funding Agencies: 

City of Tucson, American Water Works Association Research Foundation

U.S. Environmental Protection Agency (EPA)

Los Angeles County Sanitation District

Agricultural Research Service

Conact Name: 
Charles Gerba
Contact E-mail: 
Contact Address: 

Department of Soil, Water and Environmental Science

Shantz Bldg., Room 429

PO Box 210038 T

he University of Arizona Tucson, AZ 85721

Tel: (520) 621-6906, FAX: (520) 621-1647