An age-old method of harvesting water from mist is providing new life and renewed hope to some of the most water scarce and drought affected regions on earth.
The basic process of collecting water from dew droplets has been around for centuries. Often that involved the simple process of catching the water drops which fell off trees and bushes.
“In one of the first villages on the island of El Hierro, in the Spanish Canary Islands, there are graphic testimonies from the 16th and 17th centuries where you can see how they used the water from the bushes to drink,” María Victoria Marzol, a physical geography professor based at the University of La Laguna in Tenerife, was quoted saying in a recent article by the BBC.
But now, with an ever-increasing global population, and with the effects of climate change resulting in severe droughts or at least water shortages in many regions, it’s becoming more crucial to come up with innovative methods to increase water capacity.
One case study, highlighted in the same article, is taking place in Peru.
As a young boy growing up in the Cusco region of Peru, Abel Cruz had to walk for more than an hour every day to collect water.
But after noticing that water droplets gathered on banana leaves during the rainy season, he and his father devised a method of building ‘canals’ with leaves and later bamboo shoots, in order to gather the water.
Now as an adult, Cruz has been pioneering the capturing of water from mist – using large nets.
The drops are funneled from the nets into pipes and then into containers, and each net collects between 200 and 400 liters per day.
Cruz has been involved in the installation of 2000 nets in eight rural communities in his own country, as well as in Bolivia, Colombia and Mexico.
The results have been highly encouraging.
In most cases in rural areas, where there is little air pollution, the water is drinkable for humans.
Not only that, but it’s also allowed agriculture and livestock farming to flourish in dry regions.
“In Tacna, just one man is raising 1000 chickens with fog catchers,” Cruz said. “His life has changed radically. It is extraordinary. There are families that are cultivating figs, grapevines and olives, in places where you could never have imagined seeing crops.”
Big city challenges
The fog-harvesting appears to be well-tailored towards less populated rural communities, where there is more space to install nets.
People in rural regions are also generally more water conscious and use far less for personal consumption than those in larger towns and cities.
Peru’s capital, Lima, has a population of about 10 million people and is one of the driest capital cities in the world.
However, being situated next to the coast – where moist air from the sea mixes with warm winds from inland, means that there is a good supply of fog for a large portion of the year.
To capitalise on this, nets have been erected on the hills on the periphery of the city, where there is more space.
These outlying areas of the Peruvian capital are also the sections of the city where residents most feel the pinch of not having adequate water supplies – they have had to rely on trucks to bring them water, which is expensive.
Another challenge, as touched upon earlier, is air pollution. In larger cities, the poor quality of air would, of course, affect the mist.
However, water harvested in such conditions can generally still be used for irrigating crops and for animal consumption. That at least takes some of the burden of the water demands.
Purifying the water is another option.
Scientists are looking at several methods that could be implemented in order to increase the amount of water that can be collected and make the process more sustainable.
These include three-dimensional structures, which maximise water collection capacity regardless of the direction in which the wind blows the fog.
Research has also shown that in some really dry areas, there is less fog than before, or that mists are only found at higher altitudes.
One way to get around this is to build much larger, spiral-shaped fog catchers, which collect more water, at higher altitudes. These would also use up less ground space in more densely populated regions.
Present and future
There are already similar water-harvesting projects in countries such as Namibia and Morocco and there have been tests run in countries such as South Africa, Yemen, Eritrea, Dominican Republic and Cape Verde.
The west coast of the United States, the highly populated California state, in particular, has a severe water shortage and scientists are looking at the possibility of implementing fog harvesting in San Francisco.