Water storage tanks are made of various types of materials, including fibreglass, concrete and steel. Fibreglass is lightweight but can be delivered in custom shapes or sizes. Concrete provides a good foundation for the quality and durability of the tank, it's also more cost-effective than some other options. However, it can shatter if dropped. And even though steel does not usually break easily like concrete, it is quite expensive and has an unpleasant appearance (but this may be offset by how attractive your surrounding area is). Your choice might depend on many factors such as price, practicality, topography and aesthetics.