October 2011 Comments below edited
I have a number of ponds at my office, and now that I have sold the business, I have become very conscious of the water usage and the electrical usage. The first thing is that I have a lot of plant container sitting around. They vary in size from 3 gallons to 300 gallons with all types of sizes in between.
I have purposely left them all facing upward to catch rainwater and it is surprising how much they gather. When I can, I dump the smaller containers into larger ones. I also collect water from the down spouts and the shop overhang. When we have a 1/2 inch or so of rain, I collect about around 400 gallons of water then I pump these into the ponds and syphon as needed. Actually, I just start the pumps and in 30 sec or so turn them off. Since the containers are mostly uphill from the ponds, the water syphons out. Sometimes it takes many hours since the tubing is 1/2 or 3/8 or an inch diameter. That is better than using electricity.
Since I took the koi out of my main pond and placed them in the above ground pond, life has become easier. I have fewer fish, and I can catch the fish and see them better in the above ground pond. I do not use a UV but have two box type filters (photo coming). When I installed the 2nd filter what had been a watery- murky mess cleared up in two days. I was amazed. I have since placed some plants, variegated acorus, and water hyacinths in the filters. In the spring will try lettuce and some other plants for some aquaponics..
I put a small pump in the above ground pond which is attached to drip irrigation in my garden. I do not use city water any more. I provide a good water change for the fish, fertilize my garden, and as a last bonus, if I want to remove extra water from the above ground pond ( abbreviated AGP) I pump it back in the main pond where the duck weed cleans it up and removes all the ammonia is several days.
(Below was written in 2007)
I did a little calculating in the recent and present drought and was trying to determine how much rain would end up in Lake Norman after a 1 inch of rain. Lake Norman has 32,510 acres and each acre is 43, 560 square feet. That is a total of 882,677,319 gallon of water falling on Lake Norman itself. That does not count what flows downhill into the lake.
The point is if you have a collection area of any size at all, you can channel rainfall into some type of collector and collect a large quantity of water which you might be able to use for other purposes.
Also if the reservoir is above ground or higher than your garden or pond, once you start the pump you can cut it off and it will siphon all the water in your container thereby saving electricity.