Three years ago (seriously!) I started building a storage tank for water to be heated by solar panels and a woodstove. Here it is:
This week I moved it from my shop to the space it'll occupy hereafter. There's angle iron, repurposed bedframe, along the bottom edges let into the fir framing with rebar welded between. The tank is deep and I wanted to build in plenty of strength to resist the water pressure.
The concrete slab where the tank sits is far from flat. I grouted the sleepers in after shimming the framing level and poured additional concrete between the sleepers for bearing.
There are two rows of whaler running around the tank, double 2x4" on the ends and double 2x6" on the long sides. The corners are bolted using timber washers.
Tieing the long side whalers together front to back is rebar to which I welded coupling nuts. The rebar ties to angle iron outboard of the whalers. Since I couldn't reach the bolts on the back side I tack welded them to the angle.
Fiberglass insulation was added wherever possible as things went together.
The inside is lined with 3/4" fir plywood and 2 3/4" polyiso.
The one wall exposed to the rest of the room was insulated and sheathed in 7/16" OSB before the whalers and bolts/angle went on.
The tight space made the getting the tank set up a challenge. I couldn't get the plywood through the door and over the tank sides so I had to move it into the tank before the walls were complete and temporarily hang it (in the order opposite to which it was needed) out of the way on screws. I'm happy with the results so far though.
The inside measurements are 61" x 40 1/2" x 66 1/2". Assuming it gets filled to within a couple of inches of the top that's 92 cubic feet or 2,610 litres (690 US gallons).
The lid will be permanent with an access hatch and I plan to line the tank with fiberglass and vinylesther resin. So if you're interested in that phase of construction check back in say, three years :-0