How to Troubleshoot a Leaky Vinyl Liner Pond

This post is about How to Troubleshoot a Leaky Vinyl Liner Pond.  It shows how I troubleshot my two ponds that are connected together by a stream.  I was losing several hundred gallons of water a day.  After all was said and done it was leaking in three spots – one small leak in the upper pond liner, one larger leak in a hose from the lower pond to the upper pond, and the worst leak that was in the water fall section.  The waterfall section only leaked when the pump was on, but it lost a lot of water there.

How to Troubleshoot a Leaky Vinyl Liner Pond

How to Troubleshoot a Leaky Vinyl Liner Pond

The System

I have two ponds separated by a stream.  The lower pond holds about a thousand gallons of water and the upper pond holds about three hundred gallons of water.  There is a pump that takes water from the lower pond and dumps it out in a small water fall at the upper pond.  This water will fill the upper pond and will overflow into a stream that empties back into the lower pond creating a circular system.

The Problem

This past fall I shut down my pond pump.  When I started it up again this past spring, I was leaking so much water that I could not leave the system running for more than a day.  The reason was the water level would fall below the level of my skimmer on the lower pond because of leaks.


I knew the lower pond was ok because it did not have an issue all winter.  So the issue had to be in the upper pond or in the plumbing getting to the upper pond or in the stream coming back to the lower pond.

Problem #1

I noticed that with the pump off, I was losing a little water in the upper pond.  I saw this simply because with the pump off, the upper and lower ponds should stay at one consistent level.  The lower pond was, but the upper pond was losing about a half inch of water a day.  So I knew then that I had an issue with the upper pond liner, but it was not my largest issue.

Problem #2

The next logical place to look was in the flexible pipe that went from the pump in the lower pond to the waterfall in the upper pond.  So I dug the dirt around the flexible pipe so I could see what was going on.  I did find a leak right where the flexible pipe when into the waterfall area.  This was the original pipe that I put in eleven years ago, so I just went ahead and replaced the entire pipe.

I then checked the system by turning the pump on.  There were no leaks in the pipe or connections.  So I went to my day job and came back over eight hours later only to find the water level was down three inches.  There was still another leak, but only when the pond was on.

Problem #3

There were not many other things that could be leaking that much with the pump on.  The pump is submerged in water in the lower pond. So even if it was leaking, the water would just stay in the lower pond.  The pipe going up to the waterfall system was good, because it was still exposed and not leaking.  The only other options are the water fall and the stream.  I did a visual on the stream and saw nothing so it was unlikely that it was the stream.  The waterfall is quarter inch plastic, so it is unlikely that the plastic waterfall itself was the issue.  However, there is a connection from the waterfall to the vinyl liner.  Upon closer inspection I noticed that one of the nuts at this interface had corroded off and several others were almost gone.

The Fix

How to Troubleshoot a Leaky Vinyl Liner Pond – Fix Complete

I needed to replace the upper pond liner anyway to fix the leak in it and in doing so I would end up removing all of the corroded hardware.  So I figured I’d get the pond liner and replace the hardware.  When I did replace that hardware, I also used fish tank repair silicone on the hardware.  I put it on the screw head, the threads, the nuts, and in the hole.

Now with a new pipe, new liner, new hardware with added silicone, I have a leak free pond.  I do still need to dress the liner in and finish burying the hose.  Now I can get some Koi!

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The Video

Please check out our YouTube video titled Troubleshooting a Leaky Vinyl Liner Pond.

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