Charles P. Gerba, Timothy M. Straub, Joan B. Rose, Martin M. Karpiscak, Kennith E. Foster, Richard G. Brittain

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


ABSTRACT: A residential single family dwelling was retrofitted to recycle graywater for landscape irrigation and toilet flushing. The objective of this study was to determine improvements in graywater quality by evaluating five simple graywater treatment systems that were easily adapted to the household plumbing. The treatment systems consisted of (1) water hyacinths and sand filtration, (2) water hyacinths, copper ion disinfection, and sand filtration, (3) copper ion disinfection and sand filtration, (4) copper/silver ion disinfection and sand filtration, and (5) 20–μm cartridge filtration. Water quality parameters measured were fecal and total coliform indicator bacteria, nitrates, suspended solids, and turbidity. Reductions in bacterial concentration, suspended solids and turbidity were achieved by all systems tested. Treatment reduced nitrate concentrations to an average of 2.6 mg/liter. Reductions in suspended solids, and turbidity were influenced more by the quality of the graywater entering the treatment system than the efficiency of the systems themselves. The water hyacinths and sand filtration system provided the best graywater quality in terms of the concentrations of fecal indicator bacteria. The system providing the best water quality in regard to average suspended solids after treatment was the water hyacinths, copper ion, and sand filtration system, and the best average turbidity was achieved by the copper/silver ion generating unit with sand filtration. All systems were capable of significant reductions in fecal indicator bacteria, suspended solids, and turbidity; however, additional treatment or disinfection would be necessary to further reduce the level of coliform and fecal coliform bacteria to achieve regulatory standards in the State of Arizona.

Original languageEnglish (US)
Pages (from-to)109-116
Number of pages8
JournalJAWRA Journal of the American Water Resources Association
Issue number1
StatePublished - Feb 1995


  • graywater
  • waste/water/sewage treatment
  • water conservation
  • water management
  • water quality

ASJC Scopus subject areas

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


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