Here's the thing about ponds and evaporation - the variables are almost unlimited. For example - how big is your surface area? Is it humid? Windy? What's the temperature? Do you have plants? How many? How big is your waterfall? Lots of water splashing on rocks? So many factors can determine how much water you lose from your pond that it's almost impossible to compare one pond to another. Your biggest challenge will be to compare your pond to ITSELF. Learn what is normal for your pond - which just take some time. And rest assured that every new pond owner is convinced they have a leak at one time or another. Most turn out to be either a low edge somewhere or evaporation.
One thing you can do if you do suspect a leak is to turn the waterfall off and let the pond sit for 24 hours. If it's evaporation, you should still see the water go down. If it's in the waterfall (the plumbing or the actual falls) the water loss will stop.
One thing you can do if you do suspect a leak is to turn the waterfall off and let the pond sit for 24 hours. If it's evaporation, you should still see the water go down. If it's in the waterfall (the plumbing or the actual falls) the water loss will stop.