CEB Water Cistern
From Abe
I have considered a brick cistern many times, but I worry about the tension stresses over time. Of course, that will depend on how much water and how big you will make it.
If you keep it under 5 foot tall, the stresses are minimal at the bottom, no matter the diameter. I saw several designs where people used metal strapping on the outside every other course or so as a reinforcement for the bricks.
Definitely go stabilized, and then on the inside, do a thin (1/4") cement stucco (1:1 cement to VERY FINE sand), then do a thinner coat (1/8") of pure cement and water (you could add lime or acyrlic here as well) and then finish it off with one or two coats (1/8" each) of Thoroseal, or another acrylic concrete sealer.
I am hoping to do a 8000 gallon cistern in May, but I will be pouring concrete in forms. It will be reinforced a lot, but as far as time and cost are concerned, poured concrete (4-6" thick) is the cheapest way to go, especially if you are going to make more than one (cost of forms gets spread out over several cisterns).
For the floor, you'll still have to do a slab, and don't skimp on reinforcement.
If built right, ferrocement tanks can have a lifespan of more than 100 years, and I don't see why reinforced concrete or a properly reinforced CEB tank would be different.
One side note on masonry tanks - never let them dry out. They should always have a bit of water to maintain humidity and avoid major cracking.
See also http://www.fastonline.org/CD3WD_40/CD3WD/INDEX.HTM
More from Abe
I don't think there is technical difficulty, but it would be easier to just pour reinforced concrete in a form.
"The holding capacity should increase as the cube of the wall thickness" yes, up to a point, but leaks are really the issue here, cause you can have a wall 10 feet thick that would hold a bunch of water, but if it leaks, it is no good. It will be difficult to get a good seal on the bricks, cause with time, they will shift slightly, and eventually, I think it will leak.
For your waterproof layer, make sure you have acrylic in the cement and definitely fibers or metal mesh (or both).
When you like at the time it takes to lay the brick wall, then waterproof it, plus the foundation for such a thick and heavy wall, you are better off doing something like poured concrete or ferrocement. Labor and time will cost you more than your savings in the cost of the CEBs.
For CEB Cisterns plans look at the following document http://www.unhcr.org/49d089a62.html . The roofing techniques for the tanks could be adapted for housing.
From CD3WD
- http://www.fastonline.org/CD3WD_40/UWWKDTU/UGTNK/EN/UGTNK.htm
- http://www.fastonline.org/CD3WD_40/UWWKDTU/WP49/EN/WP49.htm
Metal Water Cistern with Liner
http://velacreations.blogspot.com/2010/08/cistern-is-finished.html
We just did the accounting on our new cistern. Final cost was $1,832, including all pipe (from house to cistern and back), paint, roof, liner, structure, everything. It holds approx. 6500 gallons, which comes to $0.28 per gallon, fully installed.
Not counting weather delays, we did everything in about 7 days of work with 3 people. Your hole punch could have saved us at least a day, and having a tractor on hand would have easily saved another day, maybe 2. So, with the right tools, I think you could get it up in 4 days.
Putting the metal panels together was slower than I expected, mainly because of their weight. The liner was the easiest thing, and only took an hour or so, though I had expected it to be much harder and take at least a day.
There are a few things I would do differently if I were to do it again, but for the most part, it is a decent tank that could be easily replicated. It's got about 3,000 gallons or so in it right now, and it is raining as I type this, so I am really happy with the outcome.
