(*) related to the HUMAN USAGE subchapter 5: Water use
The availability of clean water is fundamental for our basic needs such as drinking, cooking, and washing.
The World Health Organization claims that five millions people die in the world every year because of diseases related to scarcity of water or contaminated water.
Today, an increasing number of countries build sewage works for water leaving urban areas (questions a-b-f) and impose limits and monitoring of industrial and production dumping, but oftentimes that is not enough.
In fact, the environment of a watercourse can only supply good water quality if pollution remains within limits and the majority of the elements of rivers, streams, wetlands and flood areas have not been altered (for example by building canals). This way, animals and plants communities can act as a natural filter and purify waters. Healthy ecosystems are key to avoiding excessive water pollution, but even in countries with plenty of water the majority of watercourses are actually subject to alterations or unbearable pollution.
Potable water for urban supply networks usually comes from underground aquifers, but its quality strictly depends on the surface watercourses. In fact, water percolates through the soil or the river beds until it meets an impermeable clay bed, where it accumulates, begins to flow and creates an aquifer. If the surface water is polluted, it is almost sure that the aquifer below is polluted, too. While soil acts as a filter, it is not able to stop all polluting substances from reaching groundwater.
Potable water is often the result of purifying water treatment, which is designed to remove harmful substances. Treatments vary from the separation of suspensions to the removal of substances, from the transformation of the biodegradable substances to the elimination of pathogens.
Various types of treatment are used to purify drinking water and depend on the incoming water quality and the desired output (question c). Treatments can be mechanical, like filtration or sedimentation, which have the objective to eliminate the solid parts, in their more or less rough form, that are present in the water (sand, algae etc..).Chemical treatments, such as chlorination and ozonization and physical treatments as UV rays can be used to eliminate potentially harmful micro-organisms. Finally, biological treatments (questions b) such as septic tanks or a lagoon are used for waters from urban as well as industrial sources and rely on micro organisms, mainly bacteria, to decompose polluting organic substances present in the water.
During the last century, private water consumption has increased 6 fold (source: UNEP, United Nations Environment Programme). North America and Europe currently have by far the highest level of per capita water consumption, but the request of water is increasing all over the world because of development and production needs and, above all, for the demands of a higher quality of life.
A European citizen uses 130 liters of water daily on average. That is about 10 times the amount available to each person in developing countries, which is used for drinking, cooking and washing (question a). In industrial countries, water supply and sewage is usually ensured by a widespread system of waterworks and sewers. Yet, this system does not exist in developing countries, where a part of the population does not even have clean water or there is a lack of sewerage systems. Furthermore, if a supply system does exist, it is often inefficient: up to 60% of water disperses through broken pipes or is illegally diverted.
Water is fundamental for human life and for the health of natural ecosystems. Therefore, the choice of strategies to avoid waste is necessary both in countries abounding with and lacking water. Maintenance of the efficiency of water supply systems, installation of facilities for water conservation, water treating and recycling, discouragement of wasteful practices (for example, controlling consumption through counters and adopting pricing policies, which considers the actual price of water) (question d), and promotion of fair use of water through information campaigns, is therefore the duty of every community.
How much water is necessary…
- to have a bath: between 120 and 160 litres
- to have a shower of 5 minutes: between 75 and 90 litres
- to flush of toilet: up to 16 litres
- to wash hands: 1,4 litres
- to brush teeth leaving the tap running: up to 15-20 litres
- to brush teeth turning off the tap: 2 litres
- to drink and cook: about 6 litres daily per person
- to do the dishes by hand filling the bowl of the sink: 20 litres
- to wash a full load in the dishwasher: 40 litres
- to wash a full load in the washing machine: 80-120 litres
- to wash the car using a hose: 800 litres
- to air-condition an eight-story building: 3,000,000 litres daily
We have already seen that a lot of water is wasted by the supply system network, but citizens often use water without care, too. A very small amount of drinkable water is used daily for drinking and cooking, while a large amount is used for flushing toilets, washbasins, washing machines, dishwashers and baths. There are many opportunities to improve the future of water use. Small and careful everyday actions practices empower people to meditate on environmental problems and adopt fair behaviours towards a precious resource for the whole of humankind.
The following behaviours are examples of what we can do:
- Do not let the tap run, but turn it on only when necessary.
- Repair any leaks at home. A dripping tap can waste up to 4,000 litres of water a year.
- Plunge vegetables into water instead of washing them under running water: this way each family can save up to 5,000 litres a year.
- Wash only full loads in the dishwasher and the washing machine; remember to use the economy or energy saving program.
- Reduce the waste of potable water with each flush. For example use a variable flush: this way c 26000 litres a year can be saved.
- Apply a low-flow faucet aerator to your faucets/taps to reduce water flow.
- Take a shower rather than a bath.
- Water indoor plants in the morning or at dawn and, if possible, recycle the water from washing vegetables.
- If possible, do not use potable water to wash the car.