Why is my Pond Losing Water?

Why is my Pond Losing Water?

Posted on Jun 21st 2021
Author: Bill Hoffman

The heart-sinking feeling of walking out to your pond and hearing the pump sucking air because the water level is down, is enough to put anyone into a panic. Don’t fret, we are here to help you determine whether it’s a leak or possibly evaporation. Let’s troubleshoot the problem together. So, how much water does a pond lose to evaporation? Let's dive in and find out..


Leak vs Evaporation


The first thing you need to check is how much water is gone - in inches of depth.

The variables are numerous and algorithms are mind-boggling in determining evaporation rate. So, let’s just say that evaporation can cause a pond to lose anywhere from ½-inch to 2-inches of water in one night, depending on the conditions.

What we have learned, is that more cases of “water loss” seem to be reported in the spring and fall when weather temperatures swing 20-30 degrees from day to night. During this time, there is less humidity in the air, and the extreme difference between air temps and water temps will create the perfect conditions for equaling things out through evaporation.

After re-filling your pond and watching conditions closely, if you continue to have the same problem and/or it seems to get worse, regardless if it is day or night…then you probably have a leak. Do not forget, some evaporation is still happening and adding to the seemingly overwhelming amount of water that is gone.

One of the very first tests we run is shutting off the pump for a night after re-filling the pond. This will help pinpoint whether it is a leak is in the falls, hose, or stream vs. something in the pond itself.

do i have a pond leak or is it evaporation?


How Suddenly did the Problem Occur?


“My water level dropped 3-4 inches, or more, overnight.”

This usually indicates a leak has suddenly developed…the three most likely culprits would be; water has been dammed up by leaves and debris, you have overgrown plants in the bio falls, or a rodent has chewed through the liner.

  • The most obvious and easiest leak to find is a leaf dam. Water levels in streams can get backed up making pockets of water form and flow over edges of the liner. Keeping waterways clear of debris will eliminate this problem.
  • Placing aquatic plants in the bio falls is a great way to hide the box, as well as filter excess nutrients from water before it returns to the pond. Keep in mind, plants are receiving its food straight from the source and have a tendency to grow like crazy. Some maintenance is required. As plants grow, roots get fuller and begin to displace the water level - as it flows through the filter box. This can sometimes cause the water to spill over the sides of the falls box as well as the spillway. This problem can also happen when filter media gets filled up with debris from the pond, there is too much media in the falls box, or if the water flow is too heavy for the size of the spillway.
  • The last place anyone wants to start looking for a leak is looking for a chipmunk or rodent hole. Although easy to fix with a liner patch kit, it could be anywhere and the only way to find it is to start disassembling things. So, save that for last and explore other possibilities first.

“I have been having to add more and more water each day for the last week or so, maybe longer.”

You may have started out thinking that it was just evaporation, after all it does happen. But the problem seems to be getting worse… now what?!


Are you Able to See any Wet Spots Outside the Pond?

Just because you see wetness around the skimmer, does not necessarily mean that the skimmer is leaking. Since water takes the path of least resistance, a leak may start in one place and end in another - usually the lowest spot. Typically, I will start in the lowest spot (like the pond skimmer) and work my way backwards to pinpoint a leak. Many times, I have found places where the liner has settled by finding where wet spots begin.


How is the Surrounding Landscape Responding?

  • “Shrubs like Junipers or spiraea outside the pond, are turning brown and dying.” 
    • This is an indication that these plants may be drowning.
  • “Plants like Hosta, day lilies and iris are growing like gangbusters.” 
    • These plants love water and could even be sending their roots into the pond for a drink.
  • Signs like these are a good indication of where the water might be escaping. 
    • Check the edges of the liner compared to the water level. Over time, large rocks can push down edges of liner allowing water to flow out of your pond or water feature. A little at a time, the ground softens and the liner continues to sink. This allows more and more water to get out.
    • The same thing holds true for plant and tree roots. Once they detect a water source, they go for it. A long period of time may go by before you realize there is a problem. Once you discover that a nearby tree has been sipping on your pond water, you may have a larger problem than you think.

sometimes tree roots are the cause of a 'lea' in your pond


“The only wet spot I see is by the skimmer.”

  • Check the seal on the face of the skimmer. If it is an older one or was there before you moved in, inspect the screws holding the faceplate to the skimmer box itself. Some have been known to rot in the water, compromising the water-tight seal. Then check if the liner on either side of the skimmer has settled below water level. Since this area is usually back-filled during construction, it is the first place to settle.
  • If everything checks out there, the next place to look is the falls. I know that is a big jump, but there is a method to my madness. Water can spill outside of the liner at the top and travel, unseen, underneath the pond to the lowest settling point - the skimmer.
  • The seal at the waterfall box may also be compromised. As you did with the skimmer, inspect the screws. Older systems may have used rubber tape to hold the liner on. It is possible that settling of the stones have “pulled” on the liner and loosened the tape from the box.
  • Settling also happens at the falls box. Make sure that water is not flowing from the spillway and following a stone over the edge of the liner.

“I see no signs of wet spots but I am still losing water.”

  • Depending on where you live, the ground you built on can mask the problem. In places with sandy earth or soil that drains well, water can escape the pond and go straight into the ground. Unfortunately, this makes finding a leak much more difficult. By first applying the techniques described above, you may be lucky enough to find the leak right away.
  • There is also the possibility that a hose has cracked or a fitting has come apart. It has happened, on occasion, that fittings at the back of the falls begin to come loose with vibrations and force of the water flow. Once it starts to leak, tree roots can grow into the breach and literally pry it open for better access to the water. This will also give the appearance of an increasing issue over a longer period of time.
  • A good way to test your hose and fittings is to “pressurize” the system. Temporarily unplug your pond pump. Using a properly sized threaded plug, stop the water flow from inside the falls box - where water enters it through the hose. Plug the pump in again. Be certain that water is not filling the falls, and watch the water inside of your skimmer. There should be no drawing action from the pump. If you do see the water being sucked in but not filling the falls, then you know there is a breach between the pump and the box.
  • You should also make sure that the water feature was installed with only one liner. If there are any overlaps or seams, it can pose a problem too.

This blog covers most of the common water loss problems a pond could have - but if you are still stumped or have questions, feel free to use our contact us page. We also offer many pond services; like onsite consultations, water feature re-builds, and pond leak repair.