Pond Boss Forums POND CONSTRUCTION Building a dam Question on the overflow

Good thought! I don't see anything wrong with it except:

There will be water all the time in the pipe. The inside of the pipe will have peressure against it at all times. If a small pin hole forms (and it will, given enough time) the water pressure will continually force water out of the pipe, eroding the soil and possibly the dam.

With pipes constructed the other way, you only have to worry about a leak at level that is under the water surface and a foot or 2 into the soil on the pond side of the dam.