Corporate Water Accounting: An Analysis of Methods and Tools for ...

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potential (phosphorus or nitrogen units);
acidification potential (hydrogen ion or sulfur
dioxide units); and ecotoxicity potential (cubic
meter-years). Because these units are not
the same, these impacts cannot be added up
without a value judgment for normalization
and weighting of the impacts, for example as
is done for eco-indicator points or end-point
indicators.
There is research going back to the 1990s
that evaluates ecotoxicity potential with impact
units of cubic meter years, adding up the
impacts of the many different toxic substances.
These analyses are based on a so-called
“unit earth” or fugacity standardized fate and
transport model for toxic pollutants (regardless
of their medium). Information on the
ecotoxicity of the individual pollutants and
their persistence in different environmental
compartments must be known or estimated.
This kind of model is the most closely related
to the Water Footprint Network’s gray water.
It is possible to report loads of pollutants
to waterways through the simple addition
of the mass of emissions to water, but this is
not practiced within the LCA field because
there is no way to describe the environmental
mechanism to support the calculation. In effect,
such a calculation would be saying that
there is no science behind the analysis.
The use of these life cycle impact models
and reporting on the product basis supports
all the basic purposes of LCA (decisions for
engineering, policy, and purchase and sales)
as described above. It helps businesses understand
the risks of different environmental
effects for processes within the control of the
business and also for those outside the direct
control of a business. Of particular interest
are the impacts of a product downstream (the
use and recycle/disposal phases). Although
manufacturers do not control the actions of
their customers, in the case where a manufacturer
designs a product with the use and
disposal phases in mind, these phases can be
shown to have fewer polluting impacts.
Limitations
LCA is limited to the impacts for which there
is good enough science to perform impact
assessment. LCA is a relative method, normalized
to the functional unit defined in the
study. It is not typically applied to a whole
ecosystem or whole watershed analysis, and
therefore is seldom used by water resource
managers. On the other hand, the broad application
to the entire life cycle of the product
allows managers to understand where it is
possible to manage or influence the product’s
overall outcome.
WBCSD Global Water Tool
The WBCSD Global Water Tool does not
measure or otherwise assess water quality or
industrial effluent.
GEMI Water Sustainability Tools
The GEMI Water Sustainability Tool encourages
companies to analyze their pollution to
water bodies (which they perhaps confusingly
refer to as “water impacts”). It does not provide
any method or guidance for the measurement
of industrial effluents or quantification
of impacts to water quality. It looks at
both pollution caused by a company’s direct
discharges to the environment as well as
more indirect avenues of pollution such as air
deposition and the leaching of chemicals. It
provides a series of questions (categorized by
value chain stage) that help companies better
understand their effects on the pollution of
water bodies.