My garage alone will supply more than enough runoff in my area to fill the 7500 gallons of storage I plan to have in place this winter. Initially the storage is for watering my vegetable garden, as I live off a well and the cost of pumping becomes prohibitive in the summer. However, having that amount of water handy does provide me with multiple options, should the need arise.
The setup is not going to be cheap, but that is a result of my wanting/needing such a large amount. On the plus side - one time cost, long lasting, potable, and renewable.
I’m in New Mexico... this year we’ve had less than 3” of rain.