Lima is one of the largest cities in the world built on a desert. Rain barely falls, yet for much of the year a thick, gray fog rolls in from the Pacific and settles over the hills. In a few hillside neighborhoods, residents have learned to pull water straight out of that fog using nothing more than mesh nets, gutters and tanks. That practice is called fog harvesting.
For families who live far from the city's water network, every liter matters. In this article, you will learn how fog harvesting works, why it has taken root on Lima's hillsides, what it can and can't do, and what engineering and architecture students can learn from low-cost water solutions designed with communities.
According to Peru's national weather service, SENAMHI, Lima receives less than 15 millimeters of rain a year, mostly as a light drizzle known as garúa that falls mainly in winter. In those months, fog also settles over the hills.
Many families in Lima's human settlements built their homes on steep slopes at the edges of the city, often without a connection to the public water system. Many buy water from tanker trucks, and prices vary from home to home. In a 2026 El Comercio report from Pomacocha, in Villa María del Triunfo, one resident described paying S/30 to fill a 200-liter tank, while another household paid S/70 for 2,500 liters. These are individual cases, not a fixed rate. Our article on sustainable water management looks at how this challenge plays out across South America.
A fog catcher is a simple structure. A 2013 report on fog catchers in Lima describes nets of thick plastic mesh, about 6 meters wide by 4 meters tall, stretched between wooden posts anchored in concrete. As fog drifts through the mesh, tiny droplets collect on the fibers, merge and drip down.
A gutter along the bottom of the net catches the water and channels it to a holding tank. From there, residents can store it for the dry months or move it to smaller tanks near their homes.
| Component | What it does |
|---|---|
| Mesh net | Captures fog droplets as wind pushes fog through it |
| Posts and anchors | Hold the net upright against the wind |
| Gutter | Collects water dripping from the bottom of the net |
| Storage tank | Holds water for later use |
In Flor de Amancay, a neighborhood in Villa María del Triunfo in southern Lima, the 2013 report describes ten families running four fog catchers that trapped close to 600 gallons per night from April to December. The water was not potable. Families used it for washing clothes, bathing and growing vegetables like zucchini, potatoes and squash.
The practice continues today. The same 2026 El Comercio report describes 40 fog catchers in Pomacocha, installed with the Movimiento Peruanos Sin Agua, with an estimated yield of 200 to 400 liters per day per mesh.
Fog harvesting can help families save money and grow food, especially for uses that don't require drinking-quality water. It is low-tech, which makes it easier for communities to build and maintain.
The 2013 report notes that the total output of Lima's fog catchers is small compared with the city's needs. Collection depends on the season and on the location of each net. Water quality also needs to be checked before people use it for anything beyond washing or irrigation.
That's why fog harvesting works best as one piece of a broader approach that includes storage, distribution and safe sanitation. In 2017, residents of the 15A1 and 15C communities in Villa María del Triunfo worked with MEDLIFE on a community water project that pumped water uphill into storage tanks and distributed it by gravity to homes below. Low-water sanitation is another piece: read how eco-friendly bathrooms help communities facing water scarcity.
For engineering and architecture students, fog harvesting is a lesson in designing for real constraints: little money, steep terrain, harsh wind and a resource that comes and goes. It shows how simple technology can work when the community helps design, build and maintain it.
Many of these lessons connect to the broader transformation of Lima's hillside neighborhoods, explored in our article on shantytowns in transition.
Safe Homes Movement, powered by MEDLIFE, works in these same hillside communities on infrastructure residents prioritize, such as staircases, retaining walls and home construction. On the development service learning trip, students work alongside residents and local architects and engineers, who lead design and supervise construction. Trips run in summer, winter and spring in Lima, Cusco and Tena.
Fog harvesting shows how communities adapt when infrastructure doesn't reach them. Seeing those adaptations firsthand changes how you think about water, design and access.
Fill out the form to get dates, eligibility details and next steps for the Development Service Learning Trip.
Fog harvesting is a way of collecting water from fog using mesh nets. Fog droplets collect on the mesh, drip into a gutter and flow into a storage tank.
Not always. In the Lima community described in a 2013 report, the water was not potable and was used for washing, bathing and irrigation. Water quality should be tested before drinking.
Lima receives less than 15 millimeters of rain a year, but fog settles over its hills for much of the winter. In hillside neighborhoods without water connections, fog catchers offer a low-cost supplemental source of water.