Solar Desalination Skylight

“You hand pump seawater or polluted water into a bowl. Throughout the day the energy from the sun heats up this water and, instead of evaporating into the atmosphere, it gets trapped in the top section. All the fresh water will then trickle down into this bottom basin and all the impurities of the salt and polluted water stay behind. You’re going to have a left-over salt brine which is going to be a waste resource, but instead of throwing it away, this salt brine goes into the series of seawater batteries around the perimeter that can light a LED strip during the night. At night you can turn on the light and you get an energy source through the salt batteries. And during the day, this is like a skylight, bringing natural light to the interiors.”

“The power of the sun is amazing, and I was trying to copy this hydrological cycle. It can kill 99% of dangerous pathogens, remove salt brine and reduce the need of having to boil your water. I am not necessarily reinventing the wheel; solar distillers have been around for a long time, but a lot of these systems are heavy, expensive to make and with very complicated designs. I wanted to think about one which could potentially be portable and simple to construct, made out of local materials and able to Achieve a higher yield of water.”

“This new design was exactly the same but at a large scale. We created a recipe book that is a step-by-step guide on how you can create this same design using bamboo and local work. It could be flat packed into a bag and deployed very simply and quickly and then attached to a bamboo structure which allows structural rigidity but also a community shaded spot, where you can produce around 18 liters of purified water everyday.”

Read more: Low-Tech Solutions for Complex Demands: An Interview with Architect Henry Glogau, ArchDaily. Image by Henry Glogau. Hat tip to Michael.

Bike Powered Water Pumps

The Spanish NGO Azada Verde works with rural communities in Mozambique to develop sustainable and local food systems. Their bike powered water pumps save the local population much time fetching water. The pumps each supply 10 litres of water per minute. So far, 67 bike powered water pumps have been installed.

All images by Azade Verde.

The “Lavet”: A Sink, Bathtub, Shower, and Washing Machine on 1m2 of Space

Image: Marktplaats.

The lavet is a typically Dutch invention that was mainly used in social housing in the 1950s and 1960s. It was produced up to 1975, with a total production of about 1 million. The lavet is somewhere between a sink and a bathtub. It consists of a plateau with a raised edge, in which on one side is a 40 cm deep tub with a diameter of almost 60 cm. Unique to the design is the multi-functionality. The lavet fulfilled the functions of a bathroom and laundry room but required ​​only one square meter of space. [Read more…]

How to Build a Biosand Water Filter Using a Wood Mold

biosand filtersBiosand Filters use sand, gravel, and natural biological process to filter out contaminants in water, making it safe for drinking. They’re a great low-tech drinking water solution:

  • No electricity or running parts to operate the filter
  • Made with 100% locally available materials (unlike larger community based systems where foreign parts typically need to be imported)
  • Labor intensive NOT capital intensive
  • Very durable, can last more than 25 years if maintained properly
  • Little maintenance required
  • Very effective for removing bacteria, protozoa, helminths from water and reducing turbidity

The main problem with concrete biosand filters is they require a heavy, expensive steel mold to make. [Read more…]

Recharging Groundwater with Water-Harvesting Ditches

swales in colorado

“Simply put, swales are water-harvesting ditches, built on the contour of a landscape. Most ditches are designed to move water away from an area, so the bottom of the ditch is built on a modest slope, usually between 200:1 to 400:1. Swales, however, are flat on the bottom because they’re designed to do the opposite; they slow water down to a standstill, eliminate erosion, infiltrate the surrounding area with water, and recharge the groundwater table. When water moves along the flat bottom of a swale, it fills it up like a bathtub — that is, all parts of the bath tub fill at the same rate. The water in a swale is therefore passive; it doesn’t flow the way it would on a slope.” [Read more…]

Water Johads: A Low-Tech Alternative to Mega-Dams in India

water johad india

When the British colonized India, they imposed their own system of water management, which included the building of large-scale dams, sewers, and irrigation channels. This high-tech approach continues today, as the World Bank is urging India to build enormous dam projects to fight drought and depleted aquifers. The Indian government has followed its advice. Its first Prime Minister, Jawaharlal Nehru, called dams the “Temples of modern India”. Since then, India has built over 5,000 dams and large reservoirs. [1]

However, before the British arrived, people on the subcontinent used traditional low-cost, low-tech engineering to collect rainwater for thousands of years. This involved the placement of thousands of small structures throughout rural areas which, in one way or another, catch excess rainwater from the monsoon months and allow it to slowly percolate into the groundwater during the dry season. To maintain and manage these structures, community-based management schemes were necessary. However, these were actively discouraged during British rule and following independence. As a result, in the 20th century many of these small reservoirs fell into disrepair.

[Read more…]