It seems these days that unless you have a rainwater tank, or two, you will be left out of the conversations at any BBQ! Almost everyone seems to be doing their bit...I would love to know just how many megalitres of rainwater are currently stored in suburban houses.
Well, we have a 2200 slimline at the front corner of the house. The day I installed it, I didn't bother to plumb in the overflow as it was getting late and I figured I would be right until the next weekend...at 5am I awoke to the sound of water pouring onto concrete. When I went outside, the tank was already full and pouring out....I decided I had better do the overflow for sure the next weekend. Since then, we could have filled it 5 times over. I was thinking of getting another couple of thousand litres and dropping it into the gap between the side fence and the water heater, about 1.5m diameter gap. I could then plumb the bottom drains together so the two will work in tandem.
We also have a 2500 at the back of the garage. Initially we bought a 3800 but when we finally managed to get it into position, it was higher than the gutters....

. Fortunately, the supplier swapped it for a low profile one. Unfortunately, we are still waiting for it to fill up as the garage area is much smaller than the house, but it is only a couple of hundred mils off the top now...and they are expecting a lot more rain today.
I have looked at the water when filling the watering can...but I can't quite be tempted enough to actually drink it...I remember the mud I cleaned out of the gutters after I put the tank in.
So if you live in the 'burbs and so don't HAVE TO store water, have you been bitten by the rainwater bug?