Certain religious practices can also be observed in sewer use patterns. This composite hydrograph shows normal dry weather flow patterns from a flow monitor located in a region with a prominent Orthodox Jewish population. The sewer use on Fridays is quite different from other weekdays. The sewer use pattern observed on Friday, August 26, 2005 is shown for comparison.
The Jewish Sabbath, or Shabbat, begins at dusk on Friday evening. However, preparations such as shopping, cooking, cleaning, and bathing start much earlier and must be completed by dusk. The Jewish Sabbath is a time of worship, reflection, and rest, and other activities are limited during this period. Preparation for the Sabbath and rest that follows are reflected in the sewer use pattern each Friday. These patterns are repeatable from week to week. However, peak flows do shift with changing sunset times.
- Klagsbrun, F. (1996). Jewish Days — A Book of Jewish Life and Culture Around the Year, Farrar Straus Giroux; New York, NY.