1-14
October 2012
1.2
Water Management Planning
Consult the documents referenced in the Additional Resources section at the end of
this section for more specific information about conducting a water assessment.
Creating a FacilityWater Balance
The facility water balance is an accounting of all water uses at the facility. It indi-
cates the relative contribution of specific end uses to the facility’s overall water use
(
i.e., baseline) and is a powerful tool for identify-
ing, evaluating, and prioritizing water-efficiency
improvements. It also provides a mechanism to
identify water that is unaccounted for, which might
be attributed to leaks. See Tables 1-2 and 1-3 for an
example of a laboratory facility water balance. It is
important to develop a water balance for all types of
source water that a facility might be using. The fol-
lowing steps will help with creating a water balance:
••
Sum the measured or estimated water use from
all of the individual end uses for each water
source. The sum of all end uses should roughly
equal the facility’s total baseline water use.
••
For metered or submetered fixtures, equipment,
systems, and processes identified, calculate typi-
cal annual water use from meter readings, water
bills, or internal log books.
••
For unmetered fixtures, equipment, systems, and
processes identified, estimate the annual water
use from flow rate measurements collected dur-
ing the facility tour (if available) or use equip-
ment specifications and patterns of use. Consult
the relevant best management practices within
WaterSense at Work
to help
develop water use estimates for specific fixtures or equipment. Most of these
sections provide equations to help calculate water use of existing equipment and
potential retrofits or replacements.
••
In some cases, the use of onsite alternative water sources (see
Section 8: Onsite
Alternative Water Sources
)
can offset the use of potable water. Track these sources
separately in the facility water balance to fully account for all sources of supplied
water.
••
If more than 10 percent of water use cannot be accounted for in the water bal-
ance, there could be an unidentified source, a leak, or another issue warranting
further investigation. Refer to
Section 2.3: Leak Detection and Repair
to help iden-
tify and fix leaks.
