Definition: A pondless waterfall or "child-proof waterfall" is a waterfall that cascades into a subterranean catch basin or cistern rather than a pond. The collected water is then returned to the top of the waterfall by means of a pump system.
Why Pondless?
In 1984 I built what I called a "childproof" waterfall using reinforced concrete, because building codes state that because of the liability factor, ponds can only be 18" deep or you are required to conform to all of the same building codes and requirements of a swimming pool (6 foot fence perimeter, special gates, door alarms, etc.)." Since this waterfall was located in the front yard, it could not be more than 18" and if it was, there was not enough space for a large enough pond to prevent it from being sucked dry by the time the water returned back to the pond by way of the waterfall. So I installed an electronic water leveler system to insure the collection basin would automatically be replenished with water as needed. My term for this type of water feature is "child-proof" because it makes it safe for children and eliminates the liability factor and passes the building codes. Since the advent of utilizing rubber liners to construct waterfalls and ponds in the early nineties, this type of waterfall has been called a "pondless waterfall."
Rubber liner ponds and waterfalls are okay for short term use. However, they are susceptible to attacks from rats, mice, ground squirrels, gophers, chipmunks, tree roots, sharp objects, stretching from heavy boulders etc. I go into great detail on the critical flaws of pond liner construction in an article entitled Pondless Waterfalls: Concrete vs. Liners. This article contains documentation that leaves no doubt that pondless waterfalls are cheaper to build using concrete and steel rather than using a pondless waterfall liner kit. Not to mention that it is cheaper to operate and maintain.