Fog collection is most suitable for locations with frequent fog periods. Upland areas where fog is produced by the advection of clouds over the terrain or where clouds are forced to rise over mountains are most suitable, in areas of prevailing winds between 3 - 12 m/s and with no obstructions to wind flow. Fog formed on the ocean surface, or nocturnal radiation fogs in low-lying areas normally lack sufficient liquid water content or sufficient wind speeds for substantial water collection. Examine meteorological records and consult local people about their observations.
A number of meteorological and geographic considerations are important in choosing a site: predominant wind direction(persistent winds from one direction are ideal), clouds forming below the maximum terrain height, sufficient space for the fog collectors, and no major terrain obstacles. In the case of coastal cloud decks, the mountain range should be within 5 or 10 km of the coast.
If sufficient water is collected, vegetation or crops can also be planted and sustained. Once vegetation is established, it can sustain itself by catching the fog droplets directly.
==Costs==
The costs vary depending on the size of the fog catchers, quality of and access to the materials, labour, and location of the site. Small fog collectors cost between US$75 and US$200 each to build. Large 40-m² fog collectors cost between US$1,000 and US$1,500 and can last for up to ten years. A village project producing about 2,000 litres of water per day will cost about US$15,000 (FogQuest, 2011). Multiple-unit systems have the advantage of a lower cost per unit of water produced, and the number of panels in use can be changed as climatic conditions and demand for water vary (UNEP, 1997). Community participation will help to reduce the labour cost of building the fog harvesting system.
* Material: Polypropylene mesh per 1 m<sup>2</sup> (Peru and Chile): US$ 0.25
* Labour: construction and installation of large fog collectors, reservoir tanks and taps:
** Skilled labour: 140 man days (Nepal): US$ 4 per day** Unskilled labour: 400 man days (Nepal): US$ 2.75 per day
* All inclusive (materials, labour):
** Fog collectors including building materials: US$ 100 - 200** 48 m<sup>2</sup> fog collector providing 3 l/m<sup>2</sup>/day: US$ 378** Cost per m<sup>2</sup> (Nepal, including reservoir and tap): US$ 60
==Field experiences==
