Appropriate Technology



AnnaMurray BSF poster

Would you like to see the plans Dennis St. John created for building one of our All-PVC BioSand Filters? Click below.

Assembly Manual for 10 inch PVC Pipe BioSand Filter – February, 2012 -pdf.

Since it opened in January 2006, the Newton Workshop on Appropriate Technology on the outskirts of San Juan del Sur has concentrated on cheap and clever ways for people of limited means to solve perennial dilemmas—such as contaminated well water, dried-out wells, deforested hillsides, smoke-filled kitchens, and smelly aquifer-polluting latrines–without importing expensive materials from abroad. (Google “Appropriate Technology” to read the good Wikipedia entry.) To download an overview of our efforts in this area, particular in regards to water issues, click here.

  • The BioSand Filter
  • The EcoStove
  • The Composting Toilet
  • Compressed Earth Blocks
  • Rope Pumps
  • Solar-powered pumps
  • Solar Water Bottle Lamps

BioSand Filters

BioSand Filter

Invented by a Canadian working in Guatemala, the BioSand Filter is a cement box, like a large water-cooler, filled with layers of sand and gravel. Contaminated well water is poured in the top, but as it works its way down through the mass, 100% of the viruses and parasites and 96% of the diarrhea-causing E. Coli bacteria, are trapped and killed.
Since 2007 the Newton Workshop has installed over 600 such filters in rural communities around San Juan. Folks report markedly lower levels of illness. And the filtered water is delicious!

A lab in town funded by Simmons College and the Millipore Foundation tests the water for purity. In February 2007, students from Newton North High School helped workshop director Fidel Pavon install BioSand Filters in all 17 homes in the village of Papaturro. In 2008 and 2009 the Sister City Project won consecutive grants from the Conservation, Food and Health Foundation for an Anti-Parasite Campaign that brought BioSand Filters, intensive hygiene training and anti-parasite medications to 580 families. To see a slideshow about the Anti-Parasite Campaign go to

To receive a copy of a Simmons College Honors Thesis in Biology about making a BioSand Filter in Boston out of a garbage can and “rock dust”  that was able to purify water from one of the foulest creeks in New England, write to and request “Erica Boswell’s Thesis.”

NEWS FLASH: A Pilot Project to manufacture, install and test the efficacy of a new model of BioSand Filter made entirely of lightweight PVC was inaugurated in January 2012. To see a slideshow about this breakthrough go to

UPDATE: 2013 PVC BioSand Filter program ramped up:

ALSO: See our experiment with the small-scale “Filtrito” made from 5-gallon plastic buckets:



Most Nicaraguan women cook over open fires, which means they (and the children who follow them around all day) are breathing smoke all day. Little wonder that levels of asthma and emphysema are alarmingly high in rural areas.

But Newton’s EcoStove solves that problem. It’s a brick and cement cooking box up on legs: you put the wood in one end; there are two holes in the top for your favorite pots, and at the far end a chimney made of cement tubes that carries the smoke right up through the roof and away from the house.

We call it the EcoStove because it uses half the wood of an open fire, which means less cutting of trees in the surrounding watershed, which in turn means more water absorbed during the rainy season and wells less likely to go dry in March, April and May, before the rains arrive. To see a slideshow about replacing open  fires with EcoStoves, go to

To see folks making their own EcoStove components, go to

UPDATE: Here’s a set that shows new recipients of EcoStoves from late 2013 and into 2016 and beyond.  Note that families help make their own stoves:

Composting Toilets

Composting Toilet

Composting Toilet

The traditional latrine can best be thought of as a foul-smelling hole
in the ground that injects harmful fecal bacteria into surrounding
wells, especially in Nicaragua, where the soil is very porous in the rainy season, and pathogens migrate easily underground. But Newton’s Composting Toilets, in Spanish “Servicios Organicos,” use a water-tight container that sits ON the ground, not IN it. A “hammock” made of heavy-duty fishing net holds a bed of leaves and sawdust; air is allowed to circulated around it, so the human waste decomposes aerobically (with oxygen). The result is a non-smelly outhouse that does not contaminate the environment, above-ground or below. It does mean you have to climb up five steps to sit on the “throne,” but that has its own pleasures. To see a great YouTube movie of our first Composting Toilet being built, and topped by walls made of bales of rice straw sealed with home-made plaster, go to or just click here.

All three products are easily constructed using locally-available products (cement, bricks, sand, gravel, quarry stone). Most people “buy” their filters, stoves and toilets by putting in a week’s labor at the Newton Workshop, where Fidel Pavón teaches them not just what to do, but how these clever inventions work and contribute to better health and a more stable natural environment.

Compressed Earth Blocks

NEWS: Starting in 2011, we will begin experimenting with COMPRESSED EARTH BLOCKS:   Sister City Vice President David Gullette explains that Compressed Earth Blocks (CEBs) are becoming increasing popular as an alternative building material, and not only in the developing world. “Soil with a certain clay content, sometime mixed with a little sand or crushed limestone, and a little water, can produce large blocks that can be stacked in place without needing cement-based mortar. The mix is first put in the press, then a lever compresses it from below, then the press ejects the block and the process is repeated. Fortunately, the soil in our part of southern Nicaragua has a high clay content and baked crushed limestone is easily available. We look forward to beginning work in January on a preschool made entirely of CEBs.”

One reason CEBs make sense is that by using only a minimum of cement, and almost no rebar, one avoids a pair of major carbon footprints. It’s estimated that 6-8% of all greenhouse gasses are produced by manufacturing Portland cement, and making iron rebar is also extremely energy intensive.  CEBs are a green answer!

Compressed Earth Block Press

The first tests of the CEB press were begun early in 2011. To see photos go to

Later in 2011 we built a “GREEN PRESCHOOL” in Cebadilla, using CEBs, bamboo, fast-growing wood, volcanic tufa, and home-made plasters–all materials with  minimal carbon footprints compared with traditional cement/rebar/bricks. See a slideshow at

NEWS FLASH: A second “Green Preschool” in the rural community of San Antonio de Baston was completed in February 2012.  Short slideshow at

Longer slideshow at

Solar Water Bottle Lamps

In February 2012 we installed our first Solar Water Bottle lamp, and idea which is catching on around the world. A 1.5 liter water bottle is imbedded in a corrugated zinc plate, filled with water and a bit of chlorine (against algae) then placed into a hole in the roof itself, and sealed with silicone and rivets. The water acts as a crystal and refracts the equivalent of 50-50 Watts of light into the dark room below. We intend to install many more in the coming months!

We also install “rope pumps,” an easy way draw water out of wells which even a child can operate.

And we did a slightly more high-tech water project in the village of Ojochal: solar panels that power a submersible pump and an ozone generator in a water tank, which then sends water via gravity feed to 18 homes where everyone has BioSand Filters. To see photos:

Would you like to support our work in Appropriate Technology? Checks with “Appropriate Technology” on the memo line can be made out to Newton-SJ Sister City Project and sent to the treasurer of the Sister City Project, Don Ross, 211 Winslow Rd. Newton MA 02468. Contributions are 100% tax-deductible.



  1. Is there any way we can (1) purchase a biosand filter from you in San Juan del Sur for a school in Playa Gigante, and (2) get some training from your people at the workshop to learn how to build the biosand filters? We, the Rotary Club of Ventura Ca, are sponsoring an on-going project in Playa Gigante. Larry Emrich (

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