I have a 4" PVC drain in my 1 acre pond. Thought it would be wise in case of the need for mainanance. It has a PVC quarter-turn valve in a pit behind the dam so it won't freeze. I have had no problem in 5 years but I also have not used the drain. Seems like a siphon could always be used, so I am not sure if I would do it again. Not sure it the valve will work if I ever want to use it after not being used. Hope it does not break some day. Afraid to try it in case I break it.