Leaks & unexplained water loss are among the most misunderstood and misdiagnosed problems in the Oklahoma pond. On countless occasions, our staff has listened empathetically as our clients lament, “I’ve looked everywhere, and I can’t find the leak in my pond!” So before you let worry and panic set in as you search frantically for a leak, understand that to diagnose a leak without following a system is like trying to find a needle in a haystack. The basic principles of leak detection and repair will save you time, money, and headaches in your Oklahoma water gardening adventures. Just follow this simple step-by-step guide to help you determine where the leak is coming from.
Part 1 – Does My Pond Even Have A Leak?
When a pond owner sees the water line in their pond dropping like thermometer mercury during a Winnipeg cold snap, the natural assumption is that, “There must be a hole in the liner!” The truth is that over 95% of all pond ‘leaks’ are, in fact, not caused by damage to the liner at all. Here are the most probable causes:
Evaporation is caused by water turning into a vapor and escaping from your pond. The amount of water loss will vary according to the region of the country and the time of year. Ponds in Oklahoma or those located in areas of the country with high temperatures and low humidity can expect to see 1 to 3” inches of water loss per week during the spring and summer
The quantity and size of your waterfall(s) will also affect the amount of water that is lost. Regardless of the climate, a 4’x 6’pond with a 20-foot stream and 5 feet of cascading waterfalls may lose as much as 2 inches or more every day! Why? Just as wind dries clothes on a laundry line, splashing and moving water has greater exposure to air and therefore evaporates more quickly than the still waters in your pond. If that same water feature was 16′ x 21′ pond, you’d probably never even notice the additional evaporation because of its larger volume.
Now, if you fill your pond all the way up one evening, and wake up the next morning only to find the level has dropped six inches – that is a leak!
Sometimes water can escape over the edge of the liner in the pond, waterfall or stream area; this is called a low edge, and it is the most common cause of water loss in water gardens. In fact, over 50% of all water features will experience a low edge at some point due to the shifting and settling of the ground. To locate a low edge, check around the perimeter of your pond, mainly around the waterfall and stream area. Look for wet or muddy spots in the mulch and gravel. If you find an area where the water is leaking out, all you have to do is lift the liner up and push some soil under it in order to raise the edge. Bingo – leak fixed!
Reinstate your edge treatments and you’re done. Tech Tip: It’s hard to find a leak if the ground is wet. So, wait till the ground’s dry before you start looking!
Splash & Spray
Another possible cause of water loss occurs when water splashes out of your stream – and it doesn’t take much splash or spray to drain a small pond. One drop of water per second can fill a bathtub in one day! Hold up a piece of dark cloth or paper around the outside edges of your stream. If you see spots of water forming, you have a splash or spray leak. To fix a “splash leak,” all you have to do is adjust a few of the rocks under and around your waterfall. This will contain or redirect the splash inside the lined stream area and stop the leak.
Obstructions In The Waterfall or Stream
Rocks and excessive plant or algae growth, twigs, leaves and debris sometimes accumulates in the waterfalls or stream, and displaces water, thereby raising the waterline or causing the stream to back up. This can cause water to be diverted out of the water feature and lower the level in your pond. If your stream looks like it could use a little housekeeping, clear out the debris and move a few rocks around – you may find that keeping things tidy is all it takes to correct your water loss problem.
The capillary action of aquatic and perennial plants encroaching along the shoreline of your stream or pond can actually suck the water right out of your water feature. After a few seasons, you may need to thin out your plants a bit to keep water inside the liner. Note - geotextile underlayment placed within the liner as rock pads can also draw water out in the same way.
Is Your Overflow Elbow Adjusted Correctly
On the back inside wall of many skimmer models, you will see a PVC elbow fitting used to adjust the water level up or down several inches. If you have one of these in your skimmer, check and adjust the height of this elbow to be certain the water isn’t simply flowing out of the pond through this fitting and into a drainage area in the surrounding landscape.
Part 2 – Leak Detection System
If you’ve spent 30 minutes or so checking out the leak possibilities listed in Part 1 and your pond is still losing water, you may have a leak. To do this, we need to use deductive reasoning to isolate the problem: Follow this checklist to the “T” and you will find the leak:
1) Shut off your pump and fill the pond up to the maximum level and wait 24 hours. If the level does NOT drop – good news! There is no leak in the pond basin-the leak is somewhere else, so you should go directly to Step #6.
2) If the water level DOES drop, the leak is in the pond basin area. To find out where the leak is occurring, allow the water level to continue to drop until it remains at a static level for 24 hours. The level where the water stops dropping is the level where the leak is located.
3) If the water level stopped dropping above the bottom of the faceplate of your skimmer opening, it may be that the gasket seal between the liner and the skimmer face is leaking. Move a few rocks around the front of the skimmer and slide your hand behind the liner, feeling for wet soil around the opening of the skimmer. If the soil is saturated, then the faceplate may have not been installed properly and might be the source of the leak. Remove the faceplate, clean all of the old silicone off the liner, and refer back to the instruction manual on proper procedures for sealing the skimmer faceplate to the skimmer.
4) If the area outside the liner around the skimmer is dry, or the water level stopped dropping below the skimmer faceplate opening, then chances are you have a hole in the liner.
5) Concentrate your efforts by searching around the perimeter of the pond. Remove any rocks around the entire perimeter at the exact level where the water level has stopped dropping. When you find the hole, clean and thoroughly dry the liner in that area and patch it using a liner patch kit. Once you’re made the repair, fill the pond up and test to see if there are any other liner leaks. Once you are certain that the pond basin is holding water, drain it and reinstate the rockwork. Fill the pond back up one more time and enjoy!
6) If you’ve followed the instructions in Step #1 and you’ve determined that the pond basin is holding water, then the leak is going to be somewhere in the falls, stream, or plumbing.
7) Turn your pump back on and let it run until you detect water loss in the pond once again.
8) Pull up the cut edge of the liner all the way along both shorelines of the stream bed from the water line of the pond all the way up to the lip of the BioFalls filter. (Yes, I know you’ve already checked for low edges, but do it again!) Correct any low edges you may find and leave the liner exposed. Fill up the pond basin to the maximum level, keep the pump running, and wait for 24 hours to see if the pond holds water. If it does, reinstate the liner and edge treatments. If not, leave the liner exposed and proceed to Step #9.
9) It may be that the gasket seal between the BioFalls lip and the stream liner is leaking. To check this, remove some of the rocks around the front edges of the BioFalls. Wiggle you hand in behind the liner draping down in front of the BioFalls. If the ground is wet you can remove the BioFalls lip, clean it off, and reinstall the lip using a generous bead of new fish-safe silicone sealant. If the original seal is fine, and there is no water backing up over the lip of the BioFalls, yet the water feature is still losing water, move on to Step #10.
10) At this point we need to check the plumbing. As with all plumbing systems, the most common point of failure is at the connections. Start by digging up behind the BioFalls filter and check to see that the threaded connections around the bulkhead fittings aren’t dripping. Note - the rubber gaskets on all bulkhead fittings needs to be installed on the inside of the BioFalls and that all threaded PVC pipe connections should be sealed using silicone. In the same way, check the fittings and connections on the exterior back side of the skimmer filter to be certain they too are water tight. If all connections are sound, with the pump still operating, dig up and expose the flex PVC pipe between the BioFalls & the skimmer. Occasionally, rocks or other sharp debris can puncture the pipe or frost can twist and torque the pipe causing it to split. If this happens, the pipe can easily be fixed using a repair coupling.
11) The last and least likely place for a leak is in the stream liner. To deduce where the leak is, run a temporary pipe from your pump & skimmer to the middle of your stream bed, bypassing the BioFalls. If the water level in the pond stays the same, the leak is in the upper half of the stream; if it continues dropping, it’s in the lower half. Keep moving the pipe until you’ve isolated a 5′ section of stream where, when the bypass pipe is placed, you continue to lose water. Remove all the rocks and gravel in this area, rinse the liner clean and you should be able to find the hole. Repair it the same way you would a pond liner (see Step #5), test to see if the leak is gone, then reinstate all remaining exposed liner, rockwork, and edge treatments. Note – check to make sure your plants have not grown through the liner.
Still can’t find anything – Professional Intervention
If you have followed the advice and diagnosis steps in the previous two sections and yet your pond is still losing water, it’s likely that there is a flaw in the design or the construction of your water feature. At this point we recommend the professional intervention of our service department or your local CAC (Certified Aquascape Contractor) pond professional.
Tim Trammell has been building, designing, servicing and maintaining pond in the Oklahoma City Metro area for over 20 years. His company Continental Ponds, is Oklahoma's first Master Certified Aquascape Contractor and is an national award winning pond and water feature builder.