it passes through and reacts with aged water pipelines or is
held in rainwater or hot water storage tanks, it can be progressively degraded microbiologically and chemically. Project #4383
demonstrates that many water conservation strategies applied
in green building water system designs will inherently increase
water age (Figure 1). Using less water, or increasing the total storage volume of a plumbing network, tends to increase water age.
Lower water use across an entire community also increases water
age, as it increases distribution system water age.
Water age is equivalent to water residence time (i.e., detention
time), measured from the entry point of a pipeline distribution
system to its point of use. The total water age is the summation
of the distribution system water age (i.e., residence time from the
treatment facility to the water meter of a building) and premise
plumbing water age (i.e., residence time from the water meter
to the point of use).
The concept of water age arose because water generally has
very high microbiological and chemical purity when it emerges
from a treatment facility or is captured as rainfall. However, as
William J. Rhoads, Marc A. Edwards, and Charles E. Via, Department of Civil and
Environmental Engineering, Virginia Polytechnic Institute and State University
Water Research Foundation project #4383, Green Building Design: Water Quality Considerations (Rhoads et al., 2015), identifies water age as a factor that will play an increasingly important role in water quality and public health, especially as water conservation and water efficiency strategies are adopted.
Water Quality in