Susan,

I build a 13000 gallon underground ferrocement tank last year in my property. It is hard work, but can be done by yourself, with some friend's help. We finished the bottom and sides in 4 days (four people working, excavation already done).

I have also helped in the construction of above ground tanks before. Most of the ferrocement tanks here in central Brazil are build with the method Art Ludwig call “light duty” (chicken wire over welded wire mesh). It is the cheaper way we found to store large quantities of water (much cheaper than a plastic tank), and it is very reliable. I know a few ten years old + tanks that are still in very good condition.

A rule of thumb we use here is to limit the height of the tank to 8 feet to avoid excessive pressure in the bottom. Remember that it is easy to fix the chicken wire in the welded mesh laying it flat in the soil, before the assembling of the structure of the tank. Another tip is to fill it as soon as possible (wait six hours after the last cement coating), allowing the cement to finish the curing process with water inside. It helps in sealing tiny craks with mineral deposits from the leaking water.

Unfortunately, no hints about how ferrocement performs in sub freezing temperatures…

Fabio