I believe what Chris is saying is that it is not worth the expense because the amount of water added to the pond would not be significant. Here's a bean counter's run down....

In another thread you mentioned your pond is 3/4 of an acre. Lets assume that at the lowest your pond averages 4 feet deep (I have no idea what your pond averages at the lowest so I'm making an assumption here for math purposes). So .75 acre at 48" deep multiplied by 27,152 gallons per inch = 977,472 gallons in your pond.

If you had a six inch rain event and used Chris's 628 gallons per inch of rain then you would have added 3,768 gallons of water to a pond that contains almost a million gallons of water. So you would be adding only about four tenths of one percent of water to the pond.

It's not that this is a bad idea, it's just that if you are asking if it would be beneficial from a cost versus benefit standing point then the answer is probably not.

There, have I muddied the water enough for you now?

As an also and besides, here in California some folks are beginning to use water reclaimation systems that collect rain water from house gutters and then use this water for plant watering purposes.

JHAP
~~~~~~~~~~
"My mind is a raging torrent, flooded with rivulets of thought cascading into a waterfall of creative alternatives."
...Hedley Lamarr (that's Hedley not Hedy)