A customer in New Mexico recently completed an amazing underground adobe cistern and we’re thrilled to share his experience, check out the photos and account of the project from Daniel Hutchison of Localogy.org…
On this mountain, the sole source of water for both agricultural and domestic use is a traditional acequia (irrigation ditch). Before I started the house, I wanted a water source for the construction process, so I built a cistern to be filled from our small watershed.
The idea was to minimize cost / eco-footprint by using minimal cement to get the job done.
The dimensions are 18ft diameter by 6ft at the top of the wall. Got the idea from a book to make the floor cone shaped (like a jar bottom) to keep the slab in compression and save on concrete.
I dug the hole with Dr. Wilson’s Kubota (which he was crazy to lend me)
We thickened the floor near the wall with some stabilized rammed earth.
The wall of the hole was irregular, so to save cement we tried, and quickly abandoned, a rammed earth idea. I was planning on using compressed earth blocks for my house, so we laid some up for the wall to create a regular surface, add some strength, and experiment with the stabilized CEBs.
The roof was conventional domed ferro cement, with the fill hole in at the peak to maximize storage and make a waterfall that hits the apex of the floor cone, washing muck into the gutter into the sump and out of the drain (making a self-cleaning cistern).
After learning my lesson about bracing, I began to hand-plaster the undulating (sagging) ferro cement ceiling, and promptly ordered my Mortar Sprayer.
We pounded a cone shape subfloor out of dirt.
We poured a 2″ slab, flaked out some basalt rope, sprayed it down, and finished with another 2″ of concrete.
The wall was sprayed, sprayed again to receive some basalt mesh, and sprayed once more (probably an inch and a half total).
The cistern holds about 12,000 gallons without any signs of leaking. For the first time in recorded history, that source of our acequia dried up this year. Initially to fill my cistern from the main canal, we made a long lateral ditch that snakes across a slope for about a 1/4 mile. As other neighborhood cisterns go dry, I have been please to see mine incidentally topped off with the occasional gully-washer rolling off the landscape into my ditch.
The project was a good education. To do it over again, I would dig to half of the depth (being careful to preserved the cone shaped bottom), use an airform and Mortar Sprayer for the walls and roof, backfill for frost protection, and be done in a fraction of the time.