Two of the objects the Kendalls install in people's homes are water filters and stoves. Both are made primarily of concrete. On the way back from Oscar's house, we got to visit the factory where they construct the stoves. At right is one of the stoves they install. There are several models, but this one has a number of useful features including "wings" on the sides that can act as counters or tables. The stoves are very important because without them, the people need to use open-air fires, which are extremely inefficient: more smoke, less usable heat. Note the parts of the stove: the base, the firebox (which has wood sticking out above), and the "plancha" or steel plate on top. This gives them the closest thing to burners they get. Building the stove correctly is very important, because one of the many things we learned about concrete was that if it is subjected to too much heat, it breaks.
The stove seen above was actually in use at the stove factory, which is operated by a friendly entrepreneur with the solid Roman name of Marco Tulio, shown at left. (For those who forget their ancient Roman history, the personal names of the orator we know as Cicero was Marcus Tullius. I understand that this is a fairly common name down here in Guatemala.) Marco Tulio makes stoves for the Kendalls' ministry, as well as a number of other groups down here: many of the stoves we saw had the Rotary International insignia on them. He's got a fabrication process down so he can sell the stoves to ministries and clubs like Rotary as inexpensively as possible.
The Kendalls install stoves they buy from Marco Tullio's factory, but their primary ministry has always been installing water filters. They construct the water filters themselves, in their own factory. For several days now we have been working in the water filter factory, learning a bit of concrete work while we're at it. The filters use a technology called "BioSand". Here's a wikipedia article on BioSand filters, but the upshot is that there's a layer of sand that filters the water with a "schmutzdecke", or "slime layer". The filter is also made of concrete, meaning it's quite heavy, but also very durable.
Concrete also gives families the only real floors in their houses they have. Wood floors are unknown: it's either concrete or dirt. (Wood is either used for furniture or, perhaps more often, to make the "native crafts" sold in the markets and the airport.) And many floors, unfortunately, are just dirt - or, in the rainy season, mud. So, concrete floors are almost a luxury - not to mention being much more sanitary than dirt.