Modeling graywater in residences: Using shower effluent in the toilet reservoir

Xing Wu, Burcu Akinci, Cliff I. Davidson

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Use of municipal water in residences can be decreased substantially by allowing graywater effluent from showering and other activities to fill the toilet reservoir. This paper considers a system developed in Germany for treatment and storage of shower wastewater for use in flushing the toilet. Based on literature data for distributions of shower duration and water flow rate, the volume of municipal water saved using the German system has been estimated for several usage scenarios. Results show significant savings of water that depend on the size of the treatment and storage tanks used in the graywater system as well as the number of toilet flushes per day. For example, a scenario with four residents each flushing nine times per day with 80 liter treatment and storage tanks shows a 50% chance that the savings in municipal water use for the toilet will exceed 73%. Because the timing of showers and toilet flushes is assumed to follow a uniform distribution throughout the day, the calculated tank sizes may be underestimates.

Original languageEnglish (US)
Pages (from-to)111-120
Number of pages10
JournalJournal of Green Building
Issue number2
StatePublished - 2007
Externally publishedYes


  • Graywater
  • Indoor water use
  • Shower
  • Toilet
  • Water modeling

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Geography, Planning and Development
  • General Environmental Science
  • Nature and Landscape Conservation
  • Management, Monitoring, Policy and Law
  • Environmental Engineering
  • Building and Construction
  • Civil and Structural Engineering
  • Architecture


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