Biomimicry 3.8 Chaak Ha´ from Alvaro Buenfil on Vimeo.

This is a water harvesting concept that can collect water from both dew and rain. It is designed to be portable and affordable in southern Mexico.  It gets inspiration from nature in two of its main features.  (See more on the process of Finding Mentors in Nature)

The form and material of the water collecting surface were inspired from bromeliad leaves.
(Image by tonx, creative commons)

First, the form and material of the rainwater catching membrane is inspired by the way bromeliads funnel water toward a central pool.  Bromeliads are epiphytes, which mean that they grow on other plants and derive their moisture and nutrients from the air and rain. See the Ask Nature database for more information: Leaves capture water: bromeliads.

Bromelaid leaves are also hydrophobic, with microscopic irregularities that reduce adhesion and allow water to channel into a collection reservoir. The Chaac Ha uses Teflon to achieve a similar effect. 

The radial structure that supports the membrane and
the central collection tank are inspired by a spiderweb.

Second, the structure holding up the membrane is inspired by a spider web, with its radial bamboo struts held in place by tension in the membrane and by concentric radial cords just as a spiderweb's radial strands are spaced apart by concentric radial threads.  This tensegrity structure allows the device to be collapsible for transport.  

A schematic cross-section of the design

The concept is also designed to be culturally relevant, using partly local materials and named after the Mayan god of rain.

The team predicts that the design is capable of collecting a minimum of 2.5 liters of dew per night, in addition to the rainwater it catches (but the team provides no calculations).

The team also evaluated their designs against to Life’s Principles. For example, they followed an iterative design process during which the design continued to evolve (Evolve to Survive), their design can be used in both dew and rain (Adapt to Changing Conditions), and they used locally available bamboo (Be Locally Attuned and Responsive). See more at Doing Biomimicry: Natural Principles.

To see more images and explanation of the design, including some physical prototypes, see a PDF of the student’s submission to the Biomimicry Student Design Challenge.

A picture of the Chaac Ha team