Water tanks - in terms of function - are straightforward.
They are large (and sometimes small) containers that hold water. There's no moving parts and minimal maintenance required to keep them working correctly.
The more exciting element of how a water tank works is in the gathering and distribution of your water:
- Harvest the water
- Hold the water over extended periods
- Distribution of rainwater when required
Harvesting the water
For your water tank to harvest rainwater, you are going to need a catchment area. You'll most likely use the roof of your home, garage, carport or shed as a catchment area. The guttering from any of these catchment areas will run to downpipes which then brings you to your water tank!
Holding water over extended periods
This is the primary function of rainwater tanks and any tank made in Australia - to Australian standards - should carry this out without any issues.
"Surely it isn't that heavy."
For perspective, 1 litre of water is equal to 1 kilogram.
That means that a water tank at full capacity is holding an enormous amount of weight.
We would consider a 1000 litre water tank to be a small tank, but at full capacity, it is carrying one-tonne of water.
Distribution of rainwater when required.
There's really only 2 ways to distribute the water that you've captured. Choosing one or both really depends on your setup and what you want to use said rainwater for.
For the best pressure (or getting water to come out quicker) a pump is always your best option. A massive caveat, however, is that you have the right pump. This all depends on the distance you need the water to travel and how many appliances, hoses and outlets are using the same pump. But if you want that water moved around quickly - a pump is the best way to go.
All things considered - nothing is more reliable than gravity.
The trade-off is efficiency. Pressure, depending on how much water is currently in the tank, can be a bit underwhelming. But if you can have your tank placed higher than the place that you intend to use it (i.e. on a stand or if you have a raised area in your backyard), then gravity will work great. Don't use this method for household appliances, though.