Leaving a water footprint

Carbon footprint has been a buzzword
for a couple of years as people attempt to quantify their impact on the
environment. The idea is not very complex – look at the amount of carbon
dioxide your lifestyle produces and try to minimise it.

However, carbon footprint may be
facing competition from a rather surprising source – water.

The concept is quite simple: the
water we drink, wash our clothes in and cook with represents only a fraction of
the water used to sustain our way of life. For example, a cup of coffee
requires around 140 litres of water to make if you take into account the water
needed to grow and process the coffee beans until you take that first sip of
coffee in the morning. To put that in perspective, that is a bathtub full of
water. Yet that pales in comparison to the approximately 1,000 litres of water
it takes to make one litre of milk, the 2,400 litres it takes to make a burger,
or the 16,000 litres of water it takes to create one kilogramme of beef.

Internal versus external

The impact of a consumer driven
society on water resources might not be felt as keenly on local water resources
if many water-intensive products are imported. This is definitely the case for
Cayman, where the importation of most consumer goods means that the impact of what
is consumed here is felt in the countries of origin. So large amounts of water
is needed in the United States or countries in South America in order to keep
our way of life going. Although this may not be a problem many people worry
about now, it is important to keep in mind that, should Cayman suddenly need to
feed its own demand there will just not be enough to go around.

When do we run out of water?

Well, this is the one catch in the
whole argument. Although many adherents of water footprint will trumpet the
fact that a cup of coffee takes 140 litres of water, only a fraction of that
water is actually bound in your cup of coffee, and even that makes its way back
into the environment at some stage. The 140 litres is not gone, it is still
around. Some of it, like the water taken up by the tree the coffee grows on,
ends up back in the atmosphere fairly quickly, to return to earth as rain some
time later. However, water is shifted from immediately available fresh water to
another state, for although rainwater is fresh, not every drop of rain that
falls ends up where it can be collected. And although the 140 litres will make
its way back around again, it needs to be available in order to keep our way of
life going. Should a drought shift the amount of fresh water available in an
area where coffee is traditionally grown, the 140 litres needed to get that cup
of coffee to your breakfast table could suddenly become a much more valuable
commodity than the coffee it could theoretically be growing.

Water, water everywhere

Although only a tiny fraction of the
world’s water is available as fresh water,

 water abounds, with the oceans covering the
greater part of the globe. Of course, that water could be desalinated, as
indeed it is in Cayman, for use as fresh water. Yet this is where carbon
footprint and water footprint come together. Catching rainwater in a cistern
and using that as drinking water leaves virtually no carbon footprint, as very
little energy is needed to get the water from the source to the end user. Maybe
just the energy to drive a pump, or if gravity is used, then no power at all.
Drawing water from a well requires more energy and of course the well needs
drilling first, but it is still quite efficient. Although Cayman is blessed
with an abundant supply of water through the desalination of seawater, the
desalination process requires a lot more energy that drawing water from a well
does. This means that suddenly every drop of water we consume has an associated
carbon footprint and in the case of desalinated water, that footprint is bigger
than the footprint of a similar amount of water provided to the end user in a
different way.

Should the electricity used in the
process be produced through renewable sources like wind power or solar power,
the associated carbon footprint can be minimised. However, as power is produced
by burning diesel, and therefore depletes fossil fuels in the process, the
carbon footprint of a glass of water should also be a matter for concern.

Where the water goes

In the average household, water used
for drinking or cooking is just a small component of overall water use.
Showers, baths, and flushing the toilet have a much greater impact on water
consumption in a household. Fortunately it is much easier to change these
habits than it might be to give up on that cup of coffee. It will also provide
much more tangible benefits, as this has an impact on internal water footprint,
in other words on the amount of fresh water needed in Cayman to keep the
country up and running.

Although Cayman is blessed with an
abundant supply of water through the desalination of seawater, the desalination
process requires a lot more energy that drawing water from a well does