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…]

Battery Killers: Grid-Interactive Water Heaters

grid interactive water heatersGrid-interactive water heaters (GIWHs) add bidirectional control to electric resistance water heaters, allowing a utility or third-party aggregator to rapidly toggle them off and on. This functionality turns a fleet of water heaters into a flexible energy-storage medium, capable of increasing and decreasing the load on the grid on a second-by-second basis.

GIWHs are currently the least expensive form of energy storage available. Utilities can use fleets of grid-enabled water heaters for load shifting, demand response, arbitrage, ancillary services, or to respond to unexpected grid-stabilization events. Traditional dissemination of new water heater technology has been a painstakingly slow process, but water heater rental programs may greatly accelerate this process.

Read more: Battery Killers: How Water Heaters Have Evolved into Grid-Scale Energy-Storage Devices, David Podorson.

Related: How sustainable is stored sunlight?

DIY Glaciers: a Low-Cost Alternative to Dams

DIY glaciers“A remote Indian village is responding to global warming-induced water shortages by creating large masses of ice to get through the dry spring months. People in Skara and surrounding villages survive by growing crops such as barley for their own consumption and for sale in neighboring towns. In the past, water for the crops came from meltwater originating in glaciers high in the Himalaya. But in recent decades, climate change has uncoupled glacial melt cycles in the Tibetan Plateau from the traditional agricultural season, causing water shortages in April and May when Ladakhis typically begin sowing seeds for the summer season.”

“One winter in the late 1980s, an engineer from Skara named Chewang Norphel came up with a possible solution to his village’s problem while strolling around his backyard. Norphel noticed that a small stream had frozen solid under the shade of a poplar grove, though it flowed freely elsewhere in his sunny yard. The reason for this, he realized, was that the flowing water was moving too quickly to freeze, while the sluggish trickle of water beneath the grove was not. Over the next several years, Norphel worked to create an irrigation system that functioned using the same simple natural principle. The result has been Ladakh’s artificial glaciers. Ten
have been built to date.”

Read more: Artificial Glaciers Water Crops in Indian Highlands.

How to Keep Beverages Cool Outside the Refrigerator

botiijoIn the industrialized world, we know only of one way to cool beverages: place containers in refrigerators. This practice, which occurs on a massive scale, is utterly dependent on fossil fuels.

However, people obtained the same result much more sustainably before the advent of the Industrial Revolution. In hot, dry climates, we used porous earthenware jugs that were not only re-usable, but also kept water cool by taking advantage of natural energy sources.

The best known example is the Spanish ‘botijo’, an unglazed ceramic container that cools beverages by evaporation. Similar drinking containers can be found in other Mediterranean countries, as well as in Mexico (where it is known as a ‘búcaro’) and on the Indian subcontinent (where it is called a ‘ghara’, ‘matka’ or ‘suhari’).

The ceramic water cooler probably originated in the Indus Valley Civilization, which would make it 5000 years old.

[Read more…]