Foundation Dar Si Hmad


Dar Si Hmad for Development, Education and Culture

Fog Harvesting in Rural Southwest Morocco

Frequently Asked Questions

Dar Si Hmad (DSH) has built North Africa’s largest fog-collection and distribution system to serve rural, landlocked indigenous communities in the Anti-Atlas Mountains in southwest Morocco. This document contains answers to common questions about the project, both technical and social. For more information or with press inquiries, visit or email Dar Si Hmad via


Fog harvesting, fog catching, and fog milking are all names for a long-established and proven scientific technique called fog collection. This technique uses specialized mesh, hung between two poles, to trap the water droplets in the fog. The wind pushes fog through the mesh, where droplets are trapped, con- dense, fall, and amass in a container placed at the base of the unit. Drop by drop, they constitute a sub- stantial amount of water. This technique can be used in regions where fog abounds and where there are few to no viable means for conventional water access methods.

In her book, La capitatión del agua de la niebla en la isla de Tenerife (Caja Canarias: Santa Cruz de Ten- erife, 2003), Vicky Marzol shows that this is an ancient technique used by the original inhabitants of the Canary Islands. They collected fog-water under large trees that had foliage large enough to allow fog- droplets to condense and fall into previously dug holes.

Fog is composed of extremely small water-droplets (ranging between 1 µm to 40 µm) and is very similar to clouds, except its base is on the ground. Fog is present in many parts of the tropical, temperate and arid sections of the world.  There are, however, different types of fog. Fog in valleys or coastal regions is less productive than fog found in the mountains, which carries a substantial amount of water-droplets. Thus fog in coastal regions gives very little yield, which is not optimal with the current technique of harvesting fog, since the droplets are too small and pass through the nets.

Dew and fog collection are two different techniques because dew and fog are different natural phenome- na.  Fog is formed of water-droplets suspended in the air, while dew is the liquid film that forms on the surface of soil or other objects due to water condensation in the air. To collect dew, plates covered with different types of material are used. The yield of water from dew is significantly lower than the yield from fog, but it can be used for irrigation purposes or for the alleviation of water scarcity where there is a need and no other alternative available, as in the case of some regions in India.

Because water-droplets within fog are extremely small, they tend to move horizontally as the wind pushes them.  The droplets have a very low fall velocity, and wind moves them through the vertical nets where they are trapped.  High wind means an increase in water production, as it pushes more fog through the nets, but wind can also be destructive if it is too strong, as it can destabilize the collection-units.  The

ideal wind speed is 10ms-1.  The nets must be oriented towards the dominant wind direction, determined

after due observation of the wind patterns.

Various issues need to be evaluated before engaging in a large-scale fog-water harvesting project:

  1. a. Weather classification and topography of the region, b. Real and expressed need for water,
  2. c. Community acceptance, readiness and involvement in the premise of the project,
  3. d. Proven success in an experimental period of at least 1 year (a satisfactory average of collected water), e. Maintenance for project sustainability.

By the lowest value, we mean the amount of water gathered in the experimental period before a large-

scale project is considered.  The Canadian NGO FogQuest who patented and put this system in place ( considers this experimental period to be the essential step to validate or invalidate the subsequent building of a project.  Based on different worldwide experiments, FogQuest describes the annual average water-collection rate of 5 L/m2 as a potentially positive value.  The measuring occurs through the installation of Standard Fog Collectors (SFC), which are 1 m2 of mesh, and their daily moni- toring for at least a full year.


The Anti-Atlas region where Dar Si Hmad’s project is located, between Guelmim and Sidi Ifni, has a very low yearly average of precipitation: less than 132 mm yearly with a limited number of precipitation days. This is considered a Tropical Subtropical Desert Climate (Bwh) according to Köppen weather classifica- tion. These elements make fog a common phenomenon in the region. A drought cycle has been recurring since the 1960s, and ongoing climate changes have caused the situation to further deteriorate.

During the dry-season, there is a particularly dire need for water. The yearly average heat is 19.4o C and in the month of August, the average is 24.6o C. These are the temperatures close to the seashores, while within the interior of the land, during July-August, the temperature rises above 40°, with dry Chergui wind.

Historically drought is endemic in this region, but the drought has been more severe within the last three decades. In 1986, there was a particularly hard drought. Since then, the level of rainfall has decreased and desertification has seriously advanced.

Changing weather patterns indicate that the rainfall that occurred in 2014 may not be coming every year. While this past year, 2014, has seen a particularly high precipitation rate (in Guelmim, 126 mm of rain over 4 days was recorded in December 2014, causing major floods and loss of life), this doesn’t mean that the same water quantities will be available every year. Moreover, the water quality available to people in the villages via open wells is often compromised, and may continue being a vector for water borne dis- eases. Finally, if the water tables are high, and the cisterns are full, women and children still have to go fetch the water. With the pipes laid down, potable, safe, and fog-harvested water will be delivered to the inside of households, relieving the population from the task of fetching water and creating potential for further development in the region.


The president of Dar Si Hmad, Dr. Aissa Derhem, came across this technology in 1989 through the NGO

FogQuest, when he was living in Canada. Around this time, the first fog project in Camanchaca (Chile) had just been completed. A native of Aït Baamrane and thus familiar with the region’s constant fog, Dr. Derhem saw an opportunity in fog harvesting. He also had intimate knowledge of the community’s suf- fering caused by water-scarcity, and the extent to which this lack of water limited the development of his native region.

Shortly after Dr. Derhem returned to Morocco in 2000, he, with advisory support from FogQuest and technical and financial support from Dr. Vicky Marzol (University of la Laguna), set up the first Standard Fog Collector (SFC) on top of Mt. Boutmezguida. This experiment began in June 2006 and data was col- lected daily by the TV operators stationed on Boutmezguida’s summit.  In 2009, Dr. Marzol added a Da- vis Meterological Station that gave detailed and constant information about the weather patterns, further

validating the scaling of the project.  The world mean average is between 4 and 10.5 l/m2/day, and the

yield in our site is a maximum of 10.5 l/m2/day.  In general, the quantities gathered in a day vary widely. For instance in Oman, the yield reaches some 30 l/day, but only during the monsoon season which lasts

for two months. In Boutmezguida, July and August are dry months, but some days in June we get up to 50 l/day.

Dar Si Hmad has built the entire infrastructure of the project:

  • FogCollection Units: 20 completed double units for fog collection, each unit with a net-surface of 30m2, thus a total of 600 m2. Each of these units is fully equipped with gutters, filters, spigots and piping connecting them to the first reservoir.
  • Reservoirs: 7 reservoirs, including a 12 m3 double-compartment reservoir in Boutmezguida, our fog water collection site, 2 major reservoirs totaling a 467 m3 storage capacity, and 4 relay-break reservoirs with a total 60 m3 capacity
  • Technical Sheds: 5 in total, the most important being the Fog Observatory on top of Boutmezguida, the first of its kind in the world, in addition to 3 more, all connected to the relay- break reservoirs (please see attached illustration)
  • All piping through difficult, mountainous terrain
  • Pre-paid system

The fog-water passes through UV Filtering, sand and cartridge filters. All this equipment is powered by 6 solar panels and operated out of our Fog Observatory Center, which is a fully integrated rock-built eco- logical center operating with fog-water, 2 solar panels for electricity, and an Eco-San dry, recycling toilet.

29° 12′ 30″ N; 10° 01′ 30″ W, on the summit of Mt. Boutmezguida at 1,225 m.a.s.l., and 30 km inland southeast of Sidi Ifni.  The landscape is semi-arid to arid, and plants typical of the region (thyme, laven- der, spineless cacti) as well as Argan trees grow in this weather.

The anticyclone of the Azores and the cold current from the Canary Islands create evaporation and pres- sure, resulting in the production of what is called stratocumulus clouds. These clouds are based on the ground and are typically full of water. The wind pushes the clouds towards the mountains, which are colder than the sea-front, and constitute a natural barrier. This is where Dar Si Hmad has installed its fog- catching units.

The water descends by gravity from Boutmezguida to the two reservoirs located at 662 m.a.s.l.  For the first leg, water travels through 41” pipes covering a 3500 linear meters through steep mountain-slopes and is buried in trenches of 20 cm2. After reaching the two large reservoirs, totaling 464 m3, the water contin- ues its descent for 3700 linear meters via the laid piping measuring 63”, 50”, and 41” respectively to max- imize its velocity, and to finally arrive at the last village, Agni Hya, so it can be serviced with water. The

water travels a total of 7200 linear meters in the main pipes. There are also secondary pipes reaching the villages, and tertiary pipes connecting the households.


We have also built manholes that are fully equipped with meters and water-pressure regulators to facili- tate and measure the water intake of each household and village. There are 6 manholes in the first section of 3500 linear meters, which serve two main functions. First, we installed water-meters to be able to lo- cate any leak that might happen.  Second, we installed water-pressure regulators. For all these manholes, we have used concrete casting. The second section of 3700 linear meters has 4 manholes using the same equipment.

In their article “Costal Location” in Ambio (November 1991) Schemenauer and Cecereda demonstrated that a 12 m2 net has higher efficiency at the center of the net, increasing with the velocity of the wind.  If

the wind is greater than 3.5 m/s, then water-collection is stabilized at 65%. For the entire surface of the net, however, the yield is generally 20%.

Fog water does not need to be treated, as it is naturally pure. However, to mineralize the water and ensure a regular flow, fog water is mixed with safe groundwater sources before being piped to households.

Extremely light and sweet.


Dar Si Hmad’s pilot serves 5 villages located in the provinces of Tnine Amellou, Qaidat Mesti, and Sidi

Ifni. The year-round resident population is about 400 individuals in about 40 large households. In summer when villages are fully occupied, 92 large households as well as the region’s livestock are serviced.

Most households, as our original micro-surveys show, have internal cisterns. Households gather rainwater and buy water in situations of great need.  This water is delivered to their cisterns via water-trucks.  There are also open wells where water is collected daily and where livestock is brought to drink. During the dry season – the months of June through August – the water tables are low and women have to get to the wells before sunrise. Often they start walking at 4 am, covering distances of up to 5 km.  They then have to take turns filling their containers, and wait between these turns until the water-table raises.

Since we launched the project, community members have been present and have contributed to the pro- ject. Young men are now specialists in fog collection building; there are water-committees in each vil- lage; and most importantly, we have worked with the women to ensure that they sustain their privileged ancestral role as water guardians.

These communities, like all 380 villages in the region, live in situations of constant water-stress. They use an average of 8 l/d/person, which barely covers their drinking and sanitation needs. With fog water flow- ing in their homes, the calculations for consumption are projected at 30/l/d/person, a decent projection when compared to the urban water consumption in Morocco (85 l/d/person). The fog-system will provide

an average daily of 12 m3, with 53% fog-water and 47% underground water to all participating villages.

In our research and development collaboration with the German NGO Wasserstiftung (Water Founda- tion), we plan to build more efficient nets and thus increase the fog-water percentage.

Based on previous studies evaluating the impact of water being delivered to rural households, women and girls feel more empowered, there is less degradation of the natural environment, and fewer water-born diseases, especially among children.

Groundwater levels are depleted by over-use, poor management, drought, and climate change. Water quality is also compromised because most wells are open wells, not closed, protected sources.

Thanks to our Water, Sanitation and Health (WASH), Mobile Education and plumbing workshops, and continued proximity to the population, we have offered training in water-management, water savings, and optimal use.  The communities will use water in ways similar to that of other communities with running water, but with the added value that they know it comes from a special and uncommon source – fog.


Our primary research partner has been Dr. Vicky Marzol at the University of la Laguna. Dr. Marzol is doing an ongoing study comparing the weather patterns in Morocco and in her native Canary Islands. Dar Si Hmad has also carried out extensive work with the ATLAS Institute (Alliance for Technology,

Learning and Society) at the University of Colorado, when Leslie Dodson (back then doctoral candidate) designed a communication system ensuring that women retain their traditional control over water re- sources by educating them in ICT (Information and Communication Technology).

We are also cooperating with the German NGO Water Foundation (Wasserstiftung) and the Technical University of Munich. The research aims to optimize fog collection means and create strong, self- sufficient nets that can withstand extremely hard conditions. These improved nets are called Fog|Collectors, distinct from Large Fog Collectors (LGF). In addition, the Water Foundation is looking into designing an additional single, mobile, stand-alone fog collector.

We are also looking for partners to develop a system for condensing fog water using renewable energy and adapt an existing technique of dehumidification, which collects water from air humidity, but that would be suitable for fog.

For this specific project, there is ongoing research about optimizing water-yield processes. We are also engaging in sociological research to evaluate and track how water delivery inside the households is changing life for the rural communities of the Anti-Atlas.

The weather station is important to help us draw correlations between the amount of fog-water gathered and the weather conditions. In the long term, the station allows us to track and understand larger weather movements. This information is vital for the project and for expanding it to the entire region.


Each community pays a small fee, the sum of which will cover the maintenance expenses for the nets.

The communities have participated and welcomed what has seemed to them to be an unconventional idea. Currently, they are in the process of setting up a structure to learn more about how to manage the water- distribution aspect of the project in the future.

Yes, we plan to expand to other areas of the mountain where the project site is located and where our help is most needed.


Our Project Partners:

  • Local Communities
  • FogQuest, Canada
  • University of la Laguna, Tenerife, Canary Island, Spain
  • Atlas Institute, University of Colorado, USA
  • Wasserstiftung, Germany
  • Technical University of Munich, Germany
  • Qadi Ayyad University, Marrakech, Morocco
  • Vera Campbell Foundation, California, USA
  • Agence du Bassin Hydraulique de Souss-Massa-Drâa, Morocco

Financial Partners (listed in chronological order of support of the project):

  • Derhem Holding, Morocco
  • Fondation Si Hmad Derhem, Morocco
  • Dar Si Hmad for Development, Education and Culture
  • Munich Re Foundation, Munich, Germany
  • Finnish Embassy, Morocco
  • Global Green Grants, Colorado, USA
  • Waterlines, New Mexico, USA
  • Promotion Nationale, Morocco

Partners and funders have provided both technical and financial assistance.



App B4 Imm Hamria, Avenue Al Moukaouama
Agadir 80020 - Morocco


Avenue Hassan 1er Sidi Ifni - Morocco

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PO Box 20686 Agadir Principale Agadir 80000 Morocco


(+212) 528 84 30 65


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Address (AGADIR)

App B4 Imm Hamria, Avenue Al Moukaouama
Agadir 80020 - Morocco

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Avenue Hassan 1er Sidi Ifni
Tiznit - Morocco


(+212) 528 84 30 65