Our current project is building a 7200 gallon water tank. We have had 12" of rain so far this year (3.5 last night!!), which would have filled the tank had it been ready at the beginning of rain season. Still, we have more than enough rain left to fill it.
It is 8 feet tall, 12+ feet diameter and about 40 feet circumference.
- We had to dig it down about a foot and a half extra from where we had previously had the hole, so that the intake for the tank would be a bit lower than the downspout for the gutter. This extra foot and a half was in almost solid rock, which makes for a super stable base!
- We added a few inches of sand over the whole area.
- We marked the center of the hole with a rebar, where diagonals from each corner meet.
- We laid bricks in a level circle for the metal of the tank to sit on. We attached a string to the center rebar and marked a circle which would show where to lay the bricks.
- Using a jig we'd made, we drilled holes every 6 inches on both sides of the sheets of metal. There are 10 sheets of metal, each 8' x 4'.
- We bolted the sheets of metal together into a circle that sits on the center of the bricks.
- We welded and attached a frame for the roof.
- Painted everything with primer and Rustoleum.
- Filled dirt in around the cistern on the outside. This must be done evenly all the way around, so as not to shift the circle of metal.
- Attached metal to roof. The edges of this we bent inside the walls and screwed it into the walls. This allows water to run off the roof into the tank.
For photos of it all, see here.