A survey of the microbial quality of recycled household graywater

Lisa M. Casanova, Val Little, Robert J. Frye, Charles P. Gerba

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


In arid regions where populations are expanding and water is scarce, people are searching for ways to conserve and reuse water. One way homeowners can conserve water is by recycling graywater - wastewater from household sinks, showers, bathtubs, and washing machines. Graywater is used mostly for landscape irrigation. Since graywater is wastewater, reusing it raises concerns about disease transmission, either by contact with the water or the irrigated soil. The purpose of this study was to assess how factors such as number and age of household occupants, types of graywater storage, and sources of graywater used affect the microbial quality of graywater and soil irrigated with graywater. Sampies were collected over twelve months from eleven Tucson, Arizona households recycling graywater. Samples of graywater, soil irrigated by graywater, and soil irrigated by potable water were collected. We found that graywater irrigation causes a statistically significant increase in levels of fecal coliforms in soil when compared to soil irrigated with potable water. Graywater from the kitchen sink significantly increases levels of these bacteria in water and soil. Children also cause a statistically significant increase in fecal coliform levels in graywater and soil, possibly introducing a small amount of additional risk in graywater reuse.

Original languageEnglish (US)
Pages (from-to)1313-1319
Number of pages7
JournalJournal of the American Water Resources Association
Issue number5
StatePublished - 2001


  • Graywater
  • Irrigation
  • Wastewater
  • Water conservation
  • Water policy
  • Water quality

ASJC Scopus subject areas

  • Ecology
  • Water Science and Technology
  • Earth-Surface Processes


Dive into the research topics of 'A survey of the microbial quality of recycled household graywater'. Together they form a unique fingerprint.

Cite this