Sustainable water cycles

Sustainable water cycles include approaches that sustainably strengthen the water balance, and which can be integrated into food systems. These include water filtering, water treatment, seawater desalination, water harvesting, water retention systems and design concepts such as Keyline design. Elements from holistic concepts such as permaculture and regenerative agriculture are taken into account.


Aim and innovation

The approaches aim to strengthen the resilience of natural water cycles and food systems to droughts. In light of the global water shortage, this should provide for more water available for the production of food.

In many countries, there is a lot of research being conducted on how to improve the supply of fresh water through measures such as desalination and water recycling. One approach that combines many ideas into one system is the so-called Seawater Greenhouse. It is a greenhouse system in which crops are irrigated with seawater that is sustainably desalinated through solar energy[1]. The concept can be used in hot and dry regions with access to salt water or polluted groundwater[2]. As a positive side effect of the innovation, the evaporation of salt water causes a cooling and moisturizing effect of water vapor on the microclimate and thus on the plants[3]. The concept leads to significantly reduced irrigation requirements and thus lower operating costs compared to conventional greenhouse systems[4].

Scientists are also working on techniques on how to harvest water from the atmosphere to make it available for further use. Condensers, Fog Catchers and Humidity-Harvesting are examples of sustainable approaches that rely on affordable, simple equipment and materials[5]. Fog-catching is a simple method to create a sustainable source of fresh water for reforestation, horticulture and as drinking water for humans and animals[6]. The method has received increasing attention over the past decades and has continually been developed further[7]. In arid and semi-arid regions, where fresh water is scarce but fog occurs regularly, it is possible to install a passive network system for the collection of fog water[8]. The foggy air is forced by the wind through the fabric of the net, where tiny droplets are collected and together form larger drops. These flow into a collection tank. The fog collection rate varies greatly from location to location, but rates of 3 to 10 liters/per m2 of net are typical[9].

The Keyline design is a holistic design system for improving the water balance in landscapes and agricultural systems. It is based on the topographic properties and natural behavior of water[10], and is often combined with permaculture[11]. The basic idea of Keyline design is to use the water flow in agricultural landscapes in a targeted manner and to distribute it evenly. This is achieved by systematic planning and subsoiling in a cultivation pattern that corresponds to the topography of the cultivated areas[12]. Terraces, ponds, rows of trees and special soil cultivation tools such as the Keyline plough are integrated into the concept in order to infiltrate water efficiently into the soil and keep it there as long as possible[13].

Water retention systems have been developed for the regeneration of water cycles. They retain water for as long as possible where it rains down on the land. Water retention systems can vary in size, from ponds to small lakes, which are not sealed with concrete or foil, but are only lined with natural materials so that the water can slowly infiltrate into the earth. The water bodies can be linked together to form entire water retention landscapes[14]. A well-known example of retention landscapes was inspired by the permaculture pioneer Sepp Holzer and is located in the Portuguese community of Tamera, where its implementation proved a remarkable influence on food sovereignty and water self-sufficiency.


Epicuro[24], Seawater Greenhouse[25], Warka Water[26]


intermediate consumption, production


farmers, companies, associations

State of development

Initiatives and the development of technologies for sustainable water cycles are increasing rapidly in parallel with the scarcity of water. The non-profit organization 'Warka Water' has set itself the goal of building fog-catchers in dry regions[22]. Further Seawater Greenhouse systems have been established in arid regions such as the United Arab Emirates, Oman and Israel and are continuously being further developed[23].


Sustainability potential


  • biodiversity (indirect)
  • soil
  • water
  • climate (indirect)
  • air (indirect)
  • resource efficiency in production and consumption
  • promotion of regional, closed nutrient cycles


  • increase of food security
  • promotion of recycling economy


  • health: access to healthy food (indirect)

Risks / disadvantages:

The approach of the Seawater Greenhouse is highly technological. Apart from the target group of larger producers in windy coastal areas, the approach is less suitable for the production inland, since high pumping costs for sea water transport to the Seawater Greenhouse increase in parallel with the distance to the coast. On the other hand, Seawater Greenhouses do not demonstrate a feasible solution for small-scale production, since the condenser requires high initial investment[27]. For it to be useful to them, it would require governmental support, or product development of cost-effective alternatives[28].

For the successful application of Fog Catchers and Humidity-Harvesting a high humidity in the regions is necessary. In contrast to the Seawater Greenhouse, the initial costs, prerequisites and the use are much lower and simpler. A small disadvantage of the Keyline design is the less efficient soil cultivation with tractors or larger machines due to the trenches and embankments.

[1] Davies, P. und Paton, C. (2004): The Seawater Greenhouse and the Watermaker Condenser

[2] Al-Ismaili, A., & Bait Suwailam, T. (2018): Simulation Models of the Seawater Greenhouse. International Journal of Engineering & Technology, 7, p. 90. https://doi.org/10.14419/ijet.v7i3.4.16190

[3] Seawater Greenhouse (n.d.): Technology https://seawatergreenhouse.com/technology (20.02.2020)

[4] Seawater Greenhouse (n.d.): Technology https://seawatergreenhouse.com/technology (20.02.2020)

[5] Ferwati, M. S. (2019): Water harvesting cube. SN Applied Sciences, 1(7),779. https://doi.org/10.1007/s42452-019-0730-y

[6] Batisha, A. F. (2015): Feasibility and sustainability of fog harvesting. Sustainability of Water Quality and Ecology, 6, p. 1–10. https://doi.org/10.1016/j.swaqe.2015.01.002

[7] ibid.

[8] ibid.

[9] Klemm, O. et al. (2012): Fog as a Fresh-Water Resource: Overview and Perspectives. Ambio, 41(3), pp. 221–234. https://doi.org/10.1007/s13280-012-0247-8

[10] Kullik, N. (2016): Entwicklungsszenario der landwirtschaftlichen Flächennutzung durch ein Keyline Kultivierungsmuster: Die Gemeinschaft Schloss Tempelhof in Deutschland.

[11] ibid.

[12] ibid.

[13] Ridgedale Farm AB. (2019). Keyline Design—Ridgedale PERMACULTURE. http://www.ridgedalepermaculture.com/keyline-design.html (20.02.2020)

[14] Tamera (2018): Global Ecology Institute – decentralized ecological solutions. www.tamera.org/global-ecology-institute (20.02.2020); Living Gaia e.V. (2019): Naturheilung durch Retentionslandschaften—Living Gaia—Ein holistisches Heilungsbiotop in Alto Paraíso, Brasilien. https://www.living-gaia.org/wasser-retentionslandschaft.html (20.02.2020)

[15] Yazar, A., & Ali, A. (2016): Water Harvesting in Dry Environments. https://doi.org/10.1007/978-3-319-47928-6_3

[16] ibid.

[17] ibid.

[18] Oweis, T. et al. (2001): Water harvesting: Indigenous knowledge for the future of the drier environments.

[19] González, J. I. B. (2006): La captación del agua de la niebla en la isla de Tenerife. Servicio de Publicaciones de la Caja General de Ahorros de Canarias. Las Palmas de Gran Canaria. p.220. Investigaciones Geográficas (41), pp.176-178. Spanien.

[20] Ridgedale Farm AB. (2019). Keyline Design—Ridgedale PERMACULTURE.  http://www.ridgedalepermaculture.com/keyline-design.html (20.02.2020)

[21] Gioda, E. et al. (1993): Fog collectors in tropical areas. In: Becker, A., Sevruk, B. & Lapin, M.: Proceedings of the Symposium on Precipitation and Evaporation, Vol. 3 Bratislava, Slovakia, 20 - 24 September 1993, pp.273–278.

[22] Warka Water Inc. (2018): Warka Water – Every Drop Counts. http://www.warkawater.org/ (20.02.2020)

[23] Gioda, E. et al. (1993): Fog collectors in tropical areas. In: Becker, A., Sevruk, B. & Lapin, M.: Proceedings of the Symposium on Precipitation and Evaporation, Vol. 3 Bratislava, Slovakia, 20 - 24 September 1993, pp.273–278.

[24] Epicuro Solar Desalinator—Epicuro Innovations Hub (2020). https://www.epicuro.co.uk/innovations-hub/?page_id=966 (20.02.2020)

[25] Seawater Greenhouse (n.d.): Seawater Greenhouse. https://seawatergreenhouse.com (20.02.2020)

[26] Warka Water Inc. (2018): Warka Water – Every Drop Counts. http://www.warkawater.org/ (20.02.2020)

[27] Davies, P. und Paton, C. (2004): The Seawater Greenhouse and the Watermaker Condenser. p. 6.

[28] S. N. Kang’au et al. (2011): Farm water use efficiency assessment for smallholder pumped irrigation systems in the arid and semi-arid areas of Kenya. Agricultural Engineering International: CIGR Journal. Vol. 13, No. 4, 2011. Manuscript No. 1672.