You might ask yourself why water would be a concern, it is cheap, abundant and readily available whenever you need it, right?
While this holds some truth in some regions, others are not so fortunate. Water scarcity is an ever growing concern, and water conservation is high up on the aganda. And even if you happen to live in a region where fresh water is abundant it is good to be aware that water consumption is associated with an environmental cost.
In the currently common domstic system, drinkning water is produced by public water works, distributed to households where it is used for various purposes; cooking, drinking, washing, hygiene and so forth. The production, distribution and the following waste water collection and treatment relies on an infrastructure and processes, which require input of materials, energy and chemicals to function. The carbon footprint of drinking water usage is typically 40 g per cubic meter. However, about 40-60% of the water is heated locally to provide conveniant hot tap water.
Heating water is very energy demanding due to the high specific heat of water. To heat 1 liter of water from 0-100 degrees Celcius about 0.1 kWh is needed, and it takes the typical kettle about 3 minutes to do this. The same amount energy could be used to power an ordinary LED bulb for about 4 hours.