Rain Catchment

Water is an essential resource here at the Bosque. The best way to live without relying on city water is to catch and store the rain.

The rainy season in Michoacán lasts from June to September. The average annual rainfall is 77 cm (30 inches). But during the dry season from November through May, we find ourselves in near-drought conditions. Because we only get rain for four months out of the year, it is critical to our survival that we have high quality storage systems in place to keep water for showers, cooking, and occasional irrigation for the remaining eight months of the year.

The Black Rock Lodge cistern was completed in May 2006. It is the largest cistern on the property, holding 68,000 liters of water. Combined with two other cisterns and various small tanks, we collect and store over 100,000 liters of water every rainy season. So far, this has been enough to sustain our small community. In the upcoming years we will build more cisterns to accommodate our growing numbers.

Rain Water Uses

We use rain water for showers, cooking, cleaning, and occasionally for irrigation. We don't currently treat our rain water, so we do not use it as drinking water for our visitors. Unfortunately, this means that we do rely on buying drinking water from town. One of our goals is to set up a UV treatment system for our water so we can guarantee that the water from the cisterns is suitable for drinking. Until then, visitors drink bottled water that is available in all our buildings.
By using composting toilets we do not mix perfectly useful water with human waste.
We estimate that our water use is at about 35% of a usual household's.

Cistern Construction

There are many different methods for constructing water storage systems, each with advantages and disadvantages. Plastic, fiberglass, metal, concrete, and ferro-cement are all materials that are used to hold rain water. So far our cisterns have been built using stone and cement. While concrete is a high energy embodied material, our concrete cisterns should last indefinitely.

Cistern size depends on the square footage of the roof the water will be collected off of and the annual average rainfall:
Max annual gallons to capture = Annual rainfall in inches * roof square footage * .623 gallons

We build cisterns so that we can use the top for decks and patios. The largest cistern sits off the front of the Lodge and is a wonderful spot to enjoy the view of the forest and watch the birds at the birdbath. During the dry season we move a fire pit to the deck to enjoy the stars in the open air.

 

 

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