One of the first thing visitors to Guatemala, and much of Central America and Mexico, are likely to read about is the hazard of drinking local water.  To put it bluntly, drinking anything other than purified water from a reliable source is a serious ‘no-no’.  In fact, polluted water is the primary cause of diarrhea, a leading cause of death in Guatemala and many other poor countries.

Of course, most expats and many locals buy bottled water in the form of 5 gallon jugs, known locally as ‘garifones’.  You can buy them in la bodegona or the mercado (or

Simple yet elegant.

at major retailers in the city), and they are delivered by the firms themselves.  We have water delivered twice a week at a cost of 10 quetzales (about $1.20) each.  We’ve had no epidemics drinking this water, although yours truly has had more than one bout of Ciproflaxin in the last year, probably a reflection of my street eating habits more than the water at home.

Anyway, every now and then the water delivery guys don’t show for a few days, and our potable water source is dangerously low.  Sure, you can boil water, but at this altitude it takes a very long time and results in odd-tasting water that is still not definitively pure.  Plus, if there were ever a real breakdown in the supply line, we might need a longer-term, independent solution, so I began looking around for alternatives.

There are several options for walter filters, including the local company EcoFiltro, and the globally-known Berkey filter.  However, each has a limited life span and is dependent on exotic or manufactured components that might fail or otherwise be difficult to replace, especially in an emergency.  That’s why I was so excited when I heard about the BioSand filter, made from natural components and the central focus of a local NGO, Servants for Him.

Here’s how the filter works:

Water is poured into the top of the filter as needed, where a diffuser plate placed above the sand bed dissipates the initial force of the water. Traveling slowly through the sand bed, the water then passes through a bed of prepared sand media and collects in a pipe at the base of the filter. At this point, the water is propelled through plastic piping encased in the concrete exterior and out of the filter for the user to collect.

Each time water is poured into the filter, the filter ‘learns’ about the pathogens in the water and is able to better identify and trap them.  When Forrest, from Servants for Him, brought mine over and installed it, he told us it would take a few weeks of daily use for the filter to ‘learn’ enough about our water source, and then offered a much more technical explanation:

When water is poured into the top of the filter, the organic material it is carrying is trapped at the surface of the fine sand, forming a biological layer or “schmutzdecke.”  This biological layer matures over one to three weeks, depending on volume of water put through the filter and the amount of nutrients and micro-organisms in the water.

Of course, the only thing that really matters is how effective the filter is.  According to a World Health Organization study in Haiti, the filter is 98.5% effective in removing E. Coli (a nasty bug I’ve had intimate experience with).  Some data supplied by Servants for Him:

• More than 96% of fecal coliforms
• 100% of protozoa and helminthes
• 50-90% of organic and inorganic toxicants
• Greater that 75% of iron and manganese
• Suspended sediments, in all or part

One of the reasons I love this filter is it has a very long life, a decade or more.  It’s simple to operate and difficult to break.  Some of the other more modern options have a lifespan of a year or less, or have components that could easily be rendered ineffective by the small children in my house.  This concrete filter filled with sand and gravel is heavy and doesn’t attract attention, except the occasional crayon. And, unlike some of the more ‘advanced’ filters, this stuff can deal with really nasty water, so if there were ever a long-term disruption, say perhaps following a severe earthquake, a devastating Hurricane, or some sort of epidemic that disrupted or polluted normal water supplies, I could pour almost anything into this filter and, once it has adapted to the source, I’d have drinkable water.  Forrest does recommend that a few drops of bleach might help finish off any of the lingering 1.5% that makes it through.

I haven’t tested it yet but will be comparing it with the water I get from the neighborhood well (many of the gated communities here have their own wells), with city water and the bottled water that is delivered to my house.  Stay tuned!

P.S.   I know some of you engineer types will want more information so I’m going to include some pictures from the setup process.