estimating water use per occupant without assuming the fraction of indoor water use.

However, additional data from an ongoing residential water-use measurement program were made available by the American Water Works Association (DeOreo, private communication, 1997). This study has provided information on detailed daily amounts of use for a number of specific activities (clothes-washing, dishwashing, toilets, showering, baths, faucets, etc.) for 595 houses and permits a determination of the indoor use rates. It was conducted in Boulder; CO, Denver, CO; Eugene, OR; Seattle, WA; and San Diego, CA. Systems were installed in the homes to provide a log of each water use, its duration, and the total volume of water used. For some of the days being monitored, water use was extremely low, suggesting that the occupants were not home and so were not using water in the normal manner. By carefully reviewing the various records, it is possible to eliminate those values from the database. That results in the distribution observed in figure 3.3. Although there was a wide variation in total water use among the locations, there was much less variation among the indoor use rates; the average was 0.28 ± 0.20 m3 per person per day, and the geometric mean was 0.23 with a GSD of 1.8.

Figure 3.3

Cumulative probability distribution of water use per day per person based on data from Boulder, CO; Denver, CO; Eugene, OR; Seattle, WA; and San Diego, CA.



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