[pstuart]

It doesn't everywhere, and not reliably. You might not be aware that the US west coast is looking at a possible megadrought.

Your approach is fine for a rural compound, but doesn't scale for urban environments.

[WiggleYourIndex]

Last month there was a record rainfall..... 6-10 inches in urban areas.

Perhaps these pieces of wisdom could offer some guide:

"When it rains it pours"

"Get it while the gettin' is good."

"Waste not, want not."

To me, rainwater capture can apply anywhere with a roof, a sky, and a mind to build cisterns.

[seanflyon]

California already has a massive system of rain water capture and extra-large cisterns we call reservoirs. The smaller the cistern the more expensive per gallon it is.

[pstuart]

To me, you're rather out of touch. California depends upon the snowpack for a significant amount of its water supply -- and it ain't looking too good: http://cdec.water.ca.gov/cdecapp/snowapp/sweq.action

[WiggleYourIndex]

Last month there was a record rainfall.....

As that fitting expression goes, "when it rains it pours".

As another fitting expression goes, "get it while the gettin' is good."

And yet another piece of wisdom, "waste not, want not."