My parents got our local brigade to do this to our pool about 15 years ago. the brigade would have been Willunga, or one of the surrounding brigades as we lived in that area at the time...
They did provide a donation to the CFS, was like $100 or something. I was pretty young to remember the excact amount.
Personally, I wouldn't have a problem with emptying pools, but as for filling them up, I am not opposed to it, just not so sure about a few things;
e.g the water costs, and the overall image it portrays to the public who have no idea that the homeowner may have donated to the CFS, and that the CFS are not just doing it because they are mates with the home owner...