Support, exactly. Apart from the cost it's not a good look
Every situation will be some what different but the idea is to keep it as simple as possible, compromises will often be required.
Ideally tank would be as close as possible to the down pipes, not always practicable or desirable.
Tank should also be as close as possible to where the water is needed, again not always practicable or desirable.
I see quite a few people here have larger properties so water for the house is minimal and most water would be used in the gardens. So I see why you have more than one tank and various set ups.
If you don't have mains water harvesting rain water and distributing it take some planning, keeping it clean needs to be considered and of course that will require maintenance.
