Steel Rain water tanks
These are the most "classic " iconic tanks you may have seen in rural settings. Large volume, corrugated cylindrical steel tanks dot the Australian rural landscape today. These tanks are still manufactured today and often have an economical entry price based on price alone. Modern tanks are typically made from Zincalume ( grey Steel) or Colorbond ( available in different colors).
They are made round/cylindrical or Oval shapeed for narrow passage ways on the side or back of houses. Large Metal tank construction has changed over the last few years with the introduction of an interior plastic coating , " aquaplate" made by BLuescope which 
helps protect the interior surface of the metal tanks.
The purpose of the coating is to extend the life and water quality inside the tank .
Metal tanks are required to be installed above ground and usually sit on top of a concrete platform or suitable metal stand. Depending on the size of the tank and ground you may need to factor in the cost of laying concrete underneath the tank for support.
Advantages:
- Economical
- " reasonably" light weight ( compared to concrete)
- range of shapes and sizes
Disadvantages
- Limited life span
- Rusting
- Not as attractive / designer oriented
- requires cement pad or stand