By Chris Lee, Rock Garden Nursery, Sioux Falls, SD, Originally Published in Passion For Water, Spring 2007, Revised Summer 2014
One of the most frustrating experiences for a pond owner is an unexplained water loss. When a pond owner notices that the pond’s water level is dropping at a significantly faster rate than normal, most will assume that the loss is caused by a leak in the pond. There is no simple answer to the mystery of missing water and while a leak very well may be the cause, more often than not Mother Nature may be playing a role. So before we dive into a conclusion let’s consider the following causes for water loss.
Observe the current climatic conditions and how it may be impacting the evaporation process. Long streams are notorious for evaporation problems at certain times of the year. For example, a 100' stream in a windy location with full sun and a small pond at the end, it could very well drop several inches in a particular day through evaporation giving the indication of a good sized leak. So before you go tearing into a pond or stream looking for a leak, be sure to assess if water loss isn’t due to a natural evaporation process by monitoring the water level and weather conditions on a daily basis. Be sure to record temperature, humidity and wind speed to see if there is any kind of pattern that would indicate that weather conditions are the cause of the problem.
The second issue that should be assessed is excessive splash from water features such as a waterfall, stream or fountain. On days with heavy winds, splashing is increased, keeping rocks wet on the edges, which constantly adds to evaporation. Additionally, the splash may exceed the liner edge of the pond or stream.
Often, pond owners will fill the pond beyond what was intended by the builder. This causes water either to exceed the liner level or be released through an overflow which is typically connected to the back of the skimmer (assuming the pond has an overflow pipe and/or skimmer) resulting in the water dropping quickly and giving the impression of a leak. But when the water level reaches its proper level, the leak appears to have disappeared. If this seems to be the pattern, overfilling may be the cause.
Ideally, a pump which flows through the filter should run 24/7 for the health of the pond and pond fish however some pond owners frequently turn their pump on and off to save electricity. If the pond was not built to handle the additional volume of water that is added to the pond when the stream or waterfall is shut off (water in transition), the excess water will exit through the overflow or flow over the rim of the liner. Then when the pump is turned on again, the pond level is lower and it appears as though there is a leak. This can also occur without your knowledge if the skimmer mat is filled with excess debris, causing the water on the pump side of the skimmer to be lower than the level of the pond. When this occurs many pumps automatically shut off due to overheating, once the water fills to the proper level and the pump cools, the pump automatically turns on again. This process repeats itself until the skimmer mat is cleaned. So make sure the skimmer mats are cleaned regularly.
Another area to investigate is any wet ground along the edges of the pond, falls or stream. Frequently, the leak will be caused by settling or damning in the stream allowing water to sneak over the edge. Plant material can also be a contributing factor in this case.
If none of these causes fit the water loss scenario then, unfortunately, you may have a leak on your hands. Depending on the unique pond setup try to isolate if the loss seems to be caused by the stream or the pond. The leak can be narrowed down by shutting the equipment off and observing if and where the liner is punctured.
Lastly, a combination of two or more causes is also a possibility to keep in mind. Always remember when assembling your water feature: “If there is a way out, water will find it!”