How fuel storage tanks differ to water storage tanks
Rainwater tanks are used to collect or harvest rainwater. The rains that fall on your roof are directed by your gutters into a tank below. This water is normally collected for use in watering the garden, or supplying your washing machine or toilets. Water tanks can further be divided in to potable and non potable tanks. Potable water storage tanks are manufacture to store water meant for human consumption and as a result a lot of care is put into place when they are being manufactured. On the other hand, non potable water storage tanks are meant to store water not meant for human consumption. In Australia, there are strict laws with regards to drinking water from rain tanks. Proper filtration (including UV steralisation) must be connected between the tank and the outlet.
Water tanks can be buried underground, or can be placed on a firm base (concrete or gravel). Both styles of installations are good for collecting and harvesting rainwater, it just depends on how much space you have (or don't) as to which style suits you.
Speaking of styles, tanks also come in a variety of materials, shapes and designs. There are tanks made out of plastic which has advantages such as always being free from rust and other metallic elements. These also feature a black or dark green exterior to prevent algae from growing inside and making the water unsafe. They are usually made from food grade Polyethylene and feature approved resins.
There are also collapsible or "bladder" tanks. These offer large storage capacities
and come with very flexible designs. Flexible water storage devices are ideal for areas with a very harsh climate and are mostly used for holding clean drinking water. Most collapsible tanks are made from medium, commercial or industrial grade fabric and come in a pillow tank or Bladder tank design.
Steel tanks are also very reliable for storing drinking water in a very safe way. Steel tanks are made from high quality and very strong materials to ensure that your water is safely stored. Most steel tanks are lined with water compatible liners to ensure safe potable water storage.
Fuel storage tanks on the other hand are made to different specifications to rainwater tanks. Since fuel is very inflammable, these tanks are made to withstand greater temperatures, as well as being made from a resin that will not react with the fuel. Unless we're talking small fuel tanks in the home for lawn mowers etc, most fuel storage tanks are designed to be mounted to vehicles, where fuel can be transported around the farm (for example).
Fuel storage tanks can also be installed underground (as is the case in petrol stations), although most are portable. In terms of materials used, they can be made from steel, Urethane, rubber, Polymer or alloy coated fabric.
It is not recommend to use a fuel storage vessalto (then) collect rainwater, and vice versa. Residue from the fuel can kill your plants if used for watering the garden. And water in a fuel tank is no good for engines!