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Adaptation option

Water recycling

Access to adequate supplies of water is central to a sustainable future and climate change is expected to exacerbate water scarcity problems in several European regions. Recycling of water is here considered as an adaptation measure to save resources through reuse for not-for-drinking uses. Domestic water from baths, showers and sinks (grey water) can be re-used for various purposes, including toilet flushing, laundry and garden irrigation. Waste water can be used also in agriculture for irrigation. Glasshouses and industrial processes can be designed to use water in closed circuits for temperature control.

Wastewater reuse can therefore be a valuable option for water supply in areas where water is limited. Two types of reuse exist: direct and indirect. Direct reuse is treated wastewater that is piped into a water supply system without first being diluted in a natural stream/lake or groundwater. Indirect reuse involves mixing of reclaimed wastewater with another water supply before re-use. Both types are of interest as a grey climate change adaptation options. The potential water reuse is estimated to be in the order of over 3000M m3/yr. Spain alone accounts for 1200M m3/yr (Report on good practice measures for climate change adaptation in river basin management plans). Over 200 water reuse projects in Europe have been identified by the AQUAREC project.

Treated wastewater can serve as a more dependable water source, contributing to a more sustainable resource utilisation and sound demand management. The measure can reduce overall water consumption and treatment needs, resulting in cost savings. Further, the use of nutrient-rich treated waste water for agriculture may lead to a reduction (or elimination) of fertilizer application or increased productivity and can therefore also contribute to food security.  Looking at the environment, the reuse of treated water allows for the conservation and allocation of freshwater and can enhance the restoration of streams, wetlands and ponds.

Additional Details
Reference information

Adaptation Details



IPCC categories

Structural and physical: Service options, Structural and physical: Technological options

Stakeholder participation

Water recycling initiatives can be implemented at a variety of spatial scales and involve different actors. The measure is difficult to implement in countries without the an adequate institutional and normative background to facilitate re-use, or where socio-cultural acceptance and conflicts may hamper the adaptation. Stakeholder involvement is a key component of their implementation, because this adaptation option may raise several issues of concern for the general public. The potential risks associated to the use of waste-water should be examined and excluded in order to have the support of the involved stakeholders. Demonstration projects and sharing of cases of success can be part of participatory activities.

Success and Limiting Factors

Looking at the institutional setting, the implementation of the measure may require modification in legislation; another concern regards the water quality legislation for waste water irrigation, which could be too strict to allow for the re-use. The main risks of the reuse of treated water include the uncertainty of the demand of treated waste water which can limit the economic sustainability of investments. The measure can also result in more social tensions because of non-acceptance. Reuse of wastewater can also be a threat to public health, especially if illegal and unhealthy wastewater reuse practice expands rapidly due to water scarcity, over stringent regulation or the lack of appropriate treated wastewater reuse guidelines and good practice know-how (Mediterranean Wastewater Reuse Report). Better information is needed to ensure that communities are able to make well-informed decisions about recycling as a water supply option.

Costs and Benefits

The possible benefits of the reuse of treated water are various, including economic, social and environmental benefits. These benefits include reducing household water demand and ease pressure on the main water supply, reducing upstream energy and environmental costs. The cost of recycled water may exceed that of fresh water but it is justified by the series of benefits water recycling provides: it saves high quality water for drinking, it reduces the amount of polluted water released to the environment, it may have a quality making it suitable for specific uses (e.g. relative high nutrient contents may provide fertilizers through its use for irrigation). Recycled water prices may consider all those side effects and justify cheaper rates through public subsidies to encourage its use. In general, the allocation of costs is a political decision, which defines how they will be subdivided between the general taxation and fees for those interested by the benefits of re-use.

The measure is explicitly recommended in the EU CIS guidance "River Basins Management in a changing climate" and also addressed in the EU communication "Addressing the challenge of water scarcity and droughts in the European Union". In the 2007 Communication on water scarcity and droughts are also considered as potential solutions across Europe. However it is stated that any definitive Commission position on these options will have to be based on further work on risk and impact assessment, taking into account the specific bio-geographical circumstances of Member States and regions. The measure could be funded under the EU´s Rural Development Program and Cohesion policy.

Implementation Time

5-15 years.

Life Time

More than 25 years.

Reference information


DG ENV project ClimWatAdapt and FP6 project ADAM Adaptation and Mitigation Strategies

Published in Climate-ADAPT Feb 10 2021   -   Last Modified in Climate-ADAPT Sep 10 2022

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