Owner Building a Strawbale House
Water Tanks - our thoughts
Everybody needs water, and unless you are blessed with a town water supply (and even then) - you need a tank, which you fill (probably from your roof, but possibly from a creek).
Type of Tank
Pre-formed plastic, pre-cast concrete, cast-in-situ concrete, pre-formed fibreglass, galvanised iron, or plastic-lined galvanised iron. We chose the plastic-lined galvanised iron (pioneer water tanks) and have been very happy. The tank has a structural ring of galvanised iron that forms the tank wall, the tank floor is on level sand, and the tank is waterproofed by a one-piece liner (polyethylene).
The reasons we chose the plastic-lined galvanised tank:
Size of Tank(s)
We looked at the 10 year storm event data (buy data from the Bureau of Meteorology) and sized our lower tank to hold that much water (why waste a good storm dump, especially as that might be the best rain for months ?).
We looked at our expected water usage, and calculated how much we would need to have collected to survive a 3 month dry spell, and sized our total tanks for that.
We ended up with a 130Kl main collection tank (below house), a 45Kl header tank (pump up from the lower tank), and a 70Kl tank for creek water (for the vegie patch).
The first tank (creek tank, 70Kl, to be used as a header tank during the construction process, and filled by water truck) was plain galvanised steel. We cut the site for it using the backhoe we bought, then laid down a 150mm sand pad (one 11-tonne truckload). Then the local Pioneer installer does the rest, taking less than a day to get to completion, followed up by an initial load of water (one truckload, about 13Kl). The finished product.
The second tank was installed as easily as the first, but this tank is coloured (colourbond to match the house) as council isn't fond of eyesore tanks (and this one does stick out).