Thinking of getting a rainwater tank? One of the first questions you will need to answer is “how much water should we store?” Next is “how long do we need to store it?”

Excluding space and finances, you need to consider what you need the water for and therefore how much you need. For instance, if you are watering a small garden you will need less water than someone who is using a tank for a large garden and weekly washing three cars.

Let’s say you need 2,000L a month. Does that mean you should get a 2,000L tank? Maybe. If you get regular rain that will constantly fill up your tank so there is 2,000L available every month, then  that size tank may be perfect for you. However, if your annual rainfall is not evenly distributed across the year, a 2,000L tank may be too small. In many parts of Australia, we don’t tend to get a lot of rainy days during February and March, and they are hot so our gardens need more water. In that situation, a full 2,000 L tank at the beginning of February may not hold enough water to last until the next rain - a 4,000L tank would be much better.

You can use personal experience or check out the meteorology websiteto check average rainfalls  for each month to decide how big your tank will ideally be to last your needs.

Many people are surprised at the fact they need much larger tanks than they suspected. It’s much better to figure it out before you buy one than next March when your tank is dry, restrictions are in place and there is no rain…