Introduction of Water Footprints Handout

Operation Community Water Footprint: Introduction of Water Footprints

The Safe Drinking Water Foundation believes that everyone should understand how their local tap water is treated and delivered and have an idea of the cost of those processes. By ‘cost’ we are not talking about money but about hidden costs to the environment and human health impacts. This project is a guide to researching and analyzing your community’s tap water. You can calculate its use of, and impact on, fresh water supplies and also the health risks that may be present if you do not enjoy the most effective treatment processes.

A water footprint is a way to measure the total amount of fresh water used by a process, a person or a group of people and processes such as a company, community or whole country. If a person was asked to calculate their own water footprint their first idea might be to add up all the water they use for such things as bathing, flushing the toilet and washing their hands, they would add in the amount of water that they drink and/or use for cooking and cleaning and maybe some for washing the car or watering the garden. These are certainly all factors in a person’s water footprint and these are good places to start but there is a lot more to it than this. A person’s true water footprint also includes the water used to produce all of the things that that person consumes.

Pretty much everything that you buy and use has a water footprint because somewhere along the line some water was used to make that product. This is not always obvious so we will look at some examples to get used to the idea. An apple, for example, has a water footprint of 70 litres. This value is found by taking the average amount of water it takes to grow an apple tree and dividing it by the average number of apples that a tree produces. Beef is an even more interesting example, its water footprint is found by adding up the water used to grow the grains and grasses that the cow eats as well as the water that the cow drinks. The result of this calculation is that the water footprint of one kilogram of beef is 15500 litres. Products whose major ingredient is water may seem to have an easy to guess water footprint. For example, someone might guess that 2L of soda has a water footprint of about 2L but if we go back and take a close look at every step in its production we would find much more water being used than that. At the very beginning there is water being used to grow and process the sugar cane used to sweeten the soda, at the end there is extra water used in the bottling process and water is used in many of the steps in between. All together it is estimated that the water footprint of 2L of soda is about 370L.

The question that we really want to pursue is ‘What is the water footprint of 1L of tap water?’ That might seem like a silly question, you might say that 1L of water is 1L of water, but there are two important things to keep in mind. The first is that the definition of a water footprint specifies that it is the amount of ‘fresh’ water used to produce a product; this means that we have to look at the process right from the moment the water is taken from the lake, river, well or other fresh water source. The second is that your tap water goes through a treatment facility and distribution system before it gets to you and there are many places where water may be used along the way. Unfortunately, we cannot just look up the water footprint for tap water the way that we did with apples, beef and soda. Those values are available because people undertook the project and worked very hard researching, adding and averaging those water footprints but no one has attempted such a thing with tap water until now. The difficulty lies in the fact that the water footprint of tap water will be very different in different places. Some areas have very good source water and can use simpler processes and fewer chemicals to treat it (which gives a smaller footprint) while other areas have very poor quality source water and must use more chemicals and more water intensive processes (resulting in larger water footprints).

The only way to find the water footprint of your local tap water is to do some research into all the steps and processes that it goes through between its source and your tap. If you ask the right questions and can gather all of the right information you will be able to calculate the water footprint of your tap water and learn a lot more about it too.