Science in Society Archive

Using Water Sustainably

Sustainable water use tops Europe’s agenda because of its importance to food and energy security and national economy Dr. Mae-Wan Ho

Efficient water use and ecosystem protection

Clean water is becoming scarce, and existing freshwater resources are increasing under threat from human activities ([1] World Water Supply in Jeopardy, SiS 56). The European Environment Agency (EEA) has taken on the challenge to promote efficient water use in all sectors and at the same time [2] “ensuring that ecosystems have the quantity and quality of water needed to function effectively.” This follows a principle of “decoupling natural resource use and environmental impacts from economic growth” established by United Nations Environment Programme (UNEP 2011). In other words, environment protection is not to be sacrificed - nor does it need to be - for the sake of economic growth.

In its report, the EEA stresses the need to implement resource-efficient technologies in agricultural irrigation, water supply and treatment. Reducing nutrient and chemical pollution at source in agriculture, households, and industry are also important. Pricing and tariff structures have to reflect the true costs of water, internalising all externalities including environmental and resource costs.  Above all, the EEA stresses the need to integrate water, energy and land use to define common boundaries of sustainability for all users.

Vision for a resource efficient and ecologically sustainable Europe by 2050

The European Commission has elaborated a Roadmap to a resource efficient Europe in 2011 containing the following vision:

“By 2050 the EU’s economy has grown in a way that respects resource constraints and planetary boundaries, thus contributing to global economic transformation. Our economy is competitive, inclusive and provides a high standard of living with much lower environmental impacts. All resources are sustainably managed, from raw materials to energy, water, air, land and soil. Climate change milestones have been reached, while biodiversity and the ecosystem services it underpins have been protected, valued and substantially restored.”          

The EU Water Framework Directive (2000) includes specification of a ‘good status’ for biological, chemical, physical-chemical and hydromorphological elements of its water resources.

The concept of ‘environmental flows' in defining water security for ecosystems specifies the quantity, quality, and timing of water flows needed to sustain freshwater, estuarine and near-shore ecosystems and the services they provide. Measuring and maintaining environmental flows is important for protecting and enhancing these ecosystems and promoting sustainable water use.

Improving water efficiency in agriculture

Agriculture accounts for about a third of total water use in Europe, but can reach 80 % in parts of southern Europe. Although some irrigation water is returned to groundwater, typically 70 % is consumed in plant growth and lost in evapotranspiration.

Irrigation efficiency can be substantially improved by switching from open channels to pressurized pipe networks. Potentially this could reduce water abstraction by 25 % across Europe.  Field application efficiency can also be improved, by changing from furrows with an efficiency of ~55 % to sprinklers at 75 % and better yet, drip irrigation systems at 90 % efficiency.

However, increased irrigation efficiency can result in no change or even an increase in water use if efficiency gains simply drive an expansion of the irrigated area, as in the Valencia region of Spain, where a tripling of irrigation area followed efficiency improvement.  A proper pricing policy for water can avoid this.

Modification of agricultural practices can reduce crop water use. Crops with deep roots such as grapes, alfalfa and sorghum can draw on deeper layers of moisture in the soil and are able to cope better during water stress. Crops also differ in their period of peak water demand. Maize, for example, has peak demand for water in the summer when water stress is maximal. Rape, winter wheat and winter barley, on the other hand, have peak water demands in autumn and winter rather than in the summer. Early sowing can reduce the demand during the hottest part of the year. Adjusting the amount of irrigation according to crop type, growth stage, soil type and rainfall has already produced water savings of over 10% in Crete.

The practice of reusing waste water is growing in Europe and is particularly well-established in Spain, Italy, Cyprus and Greece. Water recycling is much cheaper than desalination and also avoids direct discharge into the sea. In Cyprus, the reuse target for 2014 is about 28 % of the agricultural water demand in 2008.

Illegal abstraction of water particularly from groundwater is widespread in certain parts of Europe. Monitoring is needed and must be followed up with fines or penalties sufficient to act as a deterrent.

Water use efficiency of public water systems and industry

About 20 % of water abstraction across Europe supplies public water systems, although significant variation exists between countries. Major contributions to efficiency can come from grey water reuse and rainwater harvesting, and reducing leakage in distribution and supply networks. Leakage from water mains is usually the largest component of distribution loss, and leakage from sewers can contaminate groundwater that could otherwise be used for irrigation or for drinking.

Industry can adopt techniques such as re-circulating water in cooling systems and improving cleaning methods and maintenance regimes, combined with the introduction of water metering. Project in the Spanish city of Zaragoza and the London Olympic Village show how much can be accomplished.

Water saving devices and products are now available for households, such as toilets with reduced volume of flush, washing machines and dishwashers with improved water efficiency, and water efficient showerheads. Using (grey water) from baths, showers, washbasin and washing machines for flushing toilets and watering gardens can also offer substantial savings.

Water and energy

In 2010, hydropower provided 16 % of electricity in Europe and 67 % of all renewable electricity, more than 85 % produced by large hydropower plants. Hydropower installations have potentially large environmental impacts. Dams or river-run hydropower have resulted in significant physical changes to many of Europe's rivers and lakes. Hydropower can obstruct upstream and downstream migration, and change the water flow and sediments, resulting in significant impacts on ecosystems. So far there are no agreed methods and indicators to evaluate such impacts.

Desalination creates fresh water by removing salt from sea water. Europe has about a tenth of global capacity and the biggest user, Spain, is planning a major expansion.

One key issue is the discharge of salt, either in the form of brine or solid waste from the desalination process, which includes other chemicals used in pre-treatment and membrane-cleaning. Brine is heavier than normal sea water and spreads along the sea floor threatening sensitive organisms such as the sea grass Posidonia oceanica

Desalination consumes a lot of energy. Separating salt from water takes theoretically 1.06kWh/m3, and further energy is needed for pre-treatment and processing. The EEA warns that technologies for mitigating desalination’s impacts are still in their infancy, and desalination should be considered only after all other water efficiency measures have been implemented.

Reducing pollution at source

If sources are polluted, then intense treatment measures may be required, such as ion exchange to remove nitrates and activated carbon to remove pesticides, both relatively energy intensive. Consequently, reducing pollution at source is the preferred option.

In the UK, upstream catchment management is increasingly seen as a sustainable approach to improving the quality of water for drinking, as it cuts treatment energy and costs. Successful implementation involves partnerships between water companies, NGOs such as the rivers trusts and local farmers. Peat, soils and natural fertilizers are kept on the land, and slurry management is improved.

Anaerobic digestion enables energy to be recovered in the form of biogas from wastewater treatment, making the plant partly or completely independent of energy input. Actually anaerobic digestion offers much more. I-SIS has been promoting it since 2005 as a key part of a ‘circular economy’ that recycles wastes into nutrients and energy while recovering water and preventing environmental pollution (see the most recent reports [3, 4] Sustainable Agriculture, Green Energies and the Circular Economy, SiS 46; Sustainable Agriculture and Off-Grid Renewable Energy, SiS 51).

Reduced use of fertilizers and pesticides in agriculture is very important, as pollution from agriculture remains a major cause of poor water quality in some parts of Europe [2].

The relationship between nitrogen and agricultural output in Europe is monitored by estimating the nitrogen surplus – the balance between nitrogen added to the land and nitrogen removed per hectare (in crop harvest) – and agricultural production in terms of gross value added (GVA). The results clearly show that a substantial reduction in nitrogen application is compatible with economic agricultural growth. There is much scope for more efficient use of fertilisers and pesticides. The Pesticides Directive (EU 2009) requires Member States to establish national action plans to reduce hazards, risks and dependence on chemicals for plant protection. Phosphorus is the primary cause of freshwater eutrophication, hence more efficient phosphorus use and phosphorus recovery from waste streams is paramount.

Substantial reductions in pesticide use have been achieved with little or no impact on profitability or productivity through, for example, modifying crop rotations and sowing date, selecting more pest-resistant crop varieties and buffer strips along water courses (see [5] How Famers Can Protect Water Quality, Replenish the Aquifers & Save the Soil, SIS 57).

There is a strong case for phasing out chemical fertilizers and pesticides altogether in a Europe-wide shift to organic agriculture, thereby saving energy and carbon emissions as well as our water and aquatic ecosystems (see [6] Food Futures Now *Organic *Sustainable *Fossil Fuel Free, ISIS publication). But the EEA falls short of recommending this option.

The European Water partnership has initiated a Water Stewardship Programme with corresponding mana7gement standards for reducing water and chemical use in industry [2]. Several industry sectors with high water consumption have improved their management by on-site treatment and reuse of water and improving chemical reuse. The result has been higher production yields and minimized waste, and correspondingly improved profitability. In the PROWATER project, [7] wastewater treatment and reuse, conventional physical-chemical pre-treatment and advanced post-treatment removed 62% of surfactants and 98 % colour. Freshwater use was cut by 40 %. Investment costs were recovered in about 5 years.

Better information for water management

The UN System of Environmental-Economic Accounting for Water (SEEA-W, UNSD, 2007) adopted as an interim standard framework encompasses physical supply and use tables, which analyse the origin of the water abstracted by economic sectors, transfers within the economy, and returns to land and rivers. The framework links physical and monetary information, enabling environmental and economic policy issues to be analysed together.

As the result of a decision made by the UN Committee of Experts on Environmental-Economic Accounting in June 2011, water assets and quality issues will be addressed in the second volume of the SEEA-W. Water will be measured in natural capital accounts, focusing on the water provisioning service, security of access for human and environmental use based on long term probabilities and impacts of water use on ecosystem services and environmental infrastructure. The EEA is currently developing -this approach – ecosystem capital water accounts (ECWA) - and will deliver its findings to the European Commission to support development of the ‘Blueprint to safeguard Europe’s Water Resources in summer 2012.

Whereas SEEA-W reports for economic sectors, ECWA reports for inland ecosystems.

Water footprint assessment and life cycle analysis

Water footprint assessment (WFA) is the total volume of freshwater used to produce goods and services. It divides the total into three components: blue (the volume of surface and groundwater used), green (the volume of rainwater used) and grey water (the volume of freshwater needed to dilute and assimilate pollutants to natural background concentrations and existing ambient water quality standards). WFA is now also evaluated to determine environmental, social and economic sustainability. ‘Virtual water’ is the volume of freshwater used to produce the goods traded internationally. It represents water embedded in traded products. Analysis of virtual water in exported and imported crops in Spain, for example, showed that Andalusia uses large amounts of water in its exports of potatoes, vegetables and citrus fruits, while importing cereals and arable crops with lower water requirements.

The full life cycle of a product or service ‘from cradle to grave' comprises extraction of materials from the earth, processing, and production and assembly procedures required to create the finished products or services; transportation; consumer use; and ultimately disposal of the products or waste materials.

Life cycle analysis (LCA) has been used to assess the efficiency of depollution and links to energy consumption in wastewater treatment, thereby revealing the potential environmental downside of procedures that may appear beneficial. A large number of LCA studies look at optimising the efficiency of various components of the wastewater system, such as sewage sludge treatment and disposal, phosphorus removal and recovery, and different technologies to facilitate wastewater recycling. LCA has also been applied to different drinking water supply technologies, and also across systems of supply and wastewater management systems.

The European water stewardship scheme (EWS) defines sustainable water management response strategies at the river basin scale for European water users, including industry and farmers. The EWS includes a guideline/standard and checklists for private water users to guide them towards sustainable water use, management and governance. It is highly complementary to water accounting tools, rewards sustainable practices and takes into account EU policies, including the Water Framework Directive.

Article first published 26/11/12


  1. Ho MW. World’s water in jeopardy. Science in Society 56, 38-43, 2012.
  2. Towards Efficient Use of Water Resources in Europe, EEA Report, No1/2012, European Environment Agency, 2012.
  3. Ho MW. Sustainable agriculture, green energies & the circular economy. Science in Society 46, 8-13, 2010.
  4. Ho MW. How off-grid renewables & small farms can save the world. Editorial, Science in Society 51, 2-4, 2011.
  5. Ho MW. How farmers can protect water quality, replenish aquifers & save the soil. Science in Society 57 2013.
  6. Ho MW, Burcher S, Lim LC, et al. Food Futures Now *Organic*Sustainable*Fossil-Fuel Free, ISIS/TWN, 2009, London/Penang.
  7. PROWATER – Sustainable water management in the textile wet industry through an innovative treatment process for wastewater re-use. LIFE94 ENV/IT/000583, European Commission Environment-LIFE Programme,, accessed 16 September 2012.

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Brian Sandle Comment left 28th November 2012 21:09:04
On Google Earth are visible the circular patterns made by the centre pivot spray irrigators which may have a radius of a Km. (Waiau River, NZ, for example.) They may pass over some buildings and can be programmed for water required, however taller shelter belt trees have to be removed. A few farmers plant lower indigenous shrub belts. "Efficiency" in our Canterbury Water Management Stragtegy seems to be just installing irrigators, piping the open channels and it seems re-allocating consents to take away from a farmer who may not be taking to the maximum or their consent. The cost will put off the small farmer whose open channels may also be providing for some biodiversity. Besides the majority of water in Canterbury is already over-consented. "Efficiency" does not seem to include reduced ploughing, types of crop &c to manage evapotranspiration, and I am suspicious we are only seeing the setting up of a water-selling business.

Todd Millions Comment left 19th December 2012 01:01:13
Is it even possible in modern societies to understand(have a feel) for the fact that rivers and streams aren't drainage ditches?They are better experinced,as"living things",but this doesn't happen after butt ignorant 'engineering iprovements'And flood plan realestate development..Some obscure counter examples are available-best summed in this,I think-"Place your hand in a moving stream,and you feel-The last of what was,and the first of what will be." -Leonardo Da vinci

vivek Comment left 31st January 2013 12:12:54
Thanks for your great information, the contents are quiet interesting.I will be waiting for your next post. life sciences