Figure 2. Average daily indoor per household water use REU1999 and REU2016
This 13% accounts for the bulk of excess
irrigation for the whole group.
Comparison With The 1999
Residential End Uses Of
WHILE IT IS tempting to compare total
annual use from REU1999 (146,100 gphy)
to REU2016 (88,000 gphy), it is inappropriate to do so, since the participating
utilities differed between the two studies.
Neither of these studies was designed to
be representative of all North American
locations. This limits the statistical inferences and generalizations that can be
drawn from the data.
REU1999 had 12 participating utilities,
with 12,055 households in the sample
group. Ten of the 12 participating utilities
were located in the western and southwestern United States. REU2016 had 23
participating utilities, with 23,749 homes
in the sample group. The REU2016 participating utilities are spread more diversely
throughout the United States, with many
more eastern sites.
For both REU1999 and REU2016, the
sites show extreme variation in climate
and weather, and therefore it can be supposed that households will vary greatly in
outdoor water use. It is more useful and
appropriate to compare indoor water use
between the two studies.
Indoor Daily Per Household
and Per Capita Use
INDOOR WATER USE in single-family
homes has decreased (Figures 2 and 3).
The average per household daily water
use has decreased 22%, from 177 gphd
(REU1999) to 138 gphd (REU2016). Per
capita average water use has decreased
15%, from 69.3 gpcd (REU1999) to 58.6
gpcd (REU2016). In REU1999, a household
averaged 2.77 people and in REU2016, a
household averaged 2.65 people. The
improved water efficiency of clothes
washers and toilets accounts for most of
the decreases in indoor use.