Water, a traveling molecule

Let's start with our own home. Here is a representative diagram of the percentage of domestic water used for different purposes (in a household in a developed European country):

Examine the latest water bills for your household and calculate your average household consumption.

• How many people live in your household? Calculate the consumption per person per day. It is usually between 150 and 500 litres. Are you within this range?
• How much of this consumption corresponds to what we consider basic necessities (eating and drinking)?

The physiological needs of the human body are known to account for a total of 1 m3 per year (about 2.7 litres/day). It seems clear, therefore, that in developed countries, water consumption for basic needs is far exceeded by consumption for activities associated with the standard of living.

Survey some of your colleagues, the more the better. Ask them how much water they consume and what they use it for. Write it down in order:

•  How many of you are there, where do you live, in what kind of house, in the countryside or in town, what do the members of your family do?

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•  How much water do they use, do they have a washing machine, dishwasher, etc., do they have a garden, and how often do they water it?

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•  Do you have any pets?

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Take note of all the data that can be representative when interpreting the results.
Try to find affinities between the people you have talked to and establish groups; according to the number of members living together in a house, the place where they live (country or city), according to their standard of living, according the number of household appliances that consume water… Remember that the more people you interview, the better.

• Do you think you can establish a kind of pattern of local consumption, even with a high margin of error? What conclusions do you reach? Have you been able to establish that, in general, urban consumption is higher than rural consumption?

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• Which of your interviewees consumes the most water? From the questions you have asked them, do you dare to say why they consume so much water, compared to those who consume less water?

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Read this article entitled "Saving water" published in El Periódico on 4 October 1998.

The dishwasher is an environmentally friendly appliance. This statement highlights the efforts that manufacturers have made in recent times. It can be seen that new dishwashers have reduced energy consumption by 40% and water consumption by 60%. The European Commission has set the criteria to be taken into account for the award of the EU Ecolabel. There are basically two objectives: to reduce environmental damage by reducing water and energy consumption and to limit water pollution by reducing detergent consumption. The eco-label can be identified in two ways: one, by the daisy and the other by checking that consumption is close to the maximum set for this label.

The article begins: "The dishwasher is an environmentally friendly appliance".

•  Do you think that, without going into detail, this statement is true? According to you, what conditions would a dishwasher or any other household appliance have to meet to be qualified as "environmentally friendly"?

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•  Are there any other statements that stand out to you?

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This article is far from being a technical text on household appliances. So the first thing you should do is to inform yourself a little better.

Have you ever seen the EU Ecolabel mentioned? Go to an appliance shop and ask if they have a brand of dishwasher that carries that label.

Find out how many brands are on the market that label and promote their appliances as "green". What do they offer and how are they environmentally friendly? Ask for technical information and find out what qualities and features each one offers:

Dishwasher:

•  Check the performance promised by the manufacturer - are they all similar?

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•  What energy and water savings do they achieve?

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•  What about the noise level - is it loud, not loud, or not loud at all?

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Do the same with other commonly used household appliances: washing machines, refrigerators, …