Locating a Leak in Your Pond Liner

Most direct damage to the liner produces tears and punctures. A large hole near the surface of the water may be easy to identify and evaluate. Multiple tiny holes on the decorative border or a tear along the liner’s bottom can be more challenging to figure out. Still, even if you’ve already decided to replace the liner, it’s usually worth the time to locate the damage and understand what caused it.

Locating damaged liner and the leak itself is often challenging. You can discover several methods for locating leaks on online hobby sites or by consulting your local pond supplier, but essentially most methods boil down to just two processes.

Leveling the Water

Leveling the water may be a good choice if the leak is pretty substantial and the water level drops conspicuously. If there are multiple leaks, though, this will grow to be a very tedious process that can be pretty hard on your fish, so be sure to consider your options before getting started.

In this scenario, you’ll need to turn off all your pond equipment, including your pump. Next, fill your pond to the top, then simply let it sit and leak until the water level stops dropping. This level marks the point of your (lowest) leak. Remove rocks, substrate, plants, and other decorative elements and carefully examine the perimeter of your liner right at water level. If the leak is substantial enough to create rapid water loss, you should be able to see a rip or a hole. Can you determine what caused it? Take into consideration the hole’s location, the overall condition of the liner, and the cause of the damage, if you can figure it out. If you feel pretty confident in your liner, go ahead and patch the hole and refill the pond. Since there could be more than one leak at a shallower level, you’ll need to watch for further water loss and be prepared to repeat the process.

One pond supplier suggests using a ping pong ball to help pinpoint the location of the leak. We haven’t tried it yet, but it’s a potentially brilliant idea and is certainly worth the investment in a single ping pong ball. The idea is to float the ball on the surface of your water as it levels. The ball is light enough that as water flows through the leak, the movement will draw the ball to that spot. If you can use this strategy to narrow the search to a few square feet of liner, you’ll save yourself a lot of time and frustration.

Water leveling is a tried-and-true method for locating leaks, and it has both pros and cons to consider:


  • This method does not expose your fish and plants to any foreign substances or dyes.
  • Relatively large holes can be quickly identified and assessed
  • It’s low tech and requires manual labor rather than expensive technical solutions.


  • Letting your fish sit without circulation or aeration for extended periods while you wait for the water to level can stress or even kill your fish.
  • If you have more than one leak, you’ll be forced to repeat the process several times.
  • This may not be a practical method for a relatively slow leak, since it’s less noticeable when the water has stopped moving and you may have to house your fish elsewhere for an extended period.

Using Dye or Milk

We’re not sure how we feel about using milk for this test - you’d probably need to do a water change afterward to clear out or dilute the milk, but it is time-tested. Pond dye marketed explicitly for this purpose should be fish safe and will fade over time. The idea is to pour dyed water or milk around the pond’s periphery and watch where the colored water converges. If it tends to be flowing towards a specific point, there’s your likely culprit. This method is not unlike the ping pong ball test, but the ping pong ball doesn’t leave anything behind.


  • This method gives you not only the depth of your leak but pinpoints the location more precisely.
  • This is a more nuanced test and may help you determine a likely location, even if the leak is relatively slow.


  • Dye or milk may be entirely benign for your fish and plants, but you never really can tell, can you?
  • You’ll need to turn off your equipment and remove all fish, so their movement doesn’t disrupt the water flow towards the leak. Undisturbed water works best.

Hobby sites and related businesses describe several versions of these tests, and many even offer step-by-step videos online. In the end, use whatever method works for you. Once you’ve identified the location of the leak, the probable cause, and the general condition of your existing liner, it’s time to decide your course of action.

Liners by BTL

AquaArmor Pond Liner

The most versatile liner on the market today, AquaArmor maximizes protection from harmful UV rays, tear resistance and punctures that cause leaks. Simply the best liner on the market.

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