Oh My Heavens! My Pond Is LEAKING!

(Actual Police Interview)

Pond Owner:  That’s what I’m telling you officer; Yesterday this pond was completely full of water and when I came out this morning it was half empty!

Officer:  I see.  And what makes you think it isn’t half full?

Pond Owner:  That’s not funny. Besides, I just know that someone stole it!

Officer:  Someone stole your water?  And who would want to do that?

Pond Owner:  Texas, or maybe someone really thirsty, like my neighbors dog.

Officer:  I see.  You do have a fairly large pond, but I doubt that it’s enough for the State of Texas to want it and frankly there is just no way a dog could drink that much.

Pond Owner:  It’s a pretty big dog.

Officer:  I’m leaving now.

OK, you think you have a leak.  Here are the steps to follow:

1.  Do you really have a leak?

Every pond loses water through evaporation.  How much water evaporates out of the pond depends, among other things, upon the surface area of the pond, air and water temperature, the humidity in the air, wind, and of course the splash from your water feature.  In order to judge whether you are losing water entirely due to evaporation or whether your pond actually has a leak  you need to compare how much water loss is normal for your pond, or at least ponds in your area, to how much water your pond is actually losing.  If a pond that has existed for ten years and has never before lost more than half an inch of water per day suddenly starts losing three inches per day then obviously that pond has a problem.  However, determining whether a brand new pond has a leak can be a little tougher since you have no history to compare it to.  Here in the Southwest on a hot July day it isn’t unusual to lose roughly half an inch per day to evaporation.  If the pond has a waterfall, fountain, or stream attached then you can expect to lose  a bit more, especially when the wind is blowing.

2.  Narrow down where the where the water is escaping from?

OK, so you have officially decided that water is going AWOL from your pond.  The good news is that nine times out of ten repairing the problem is very easy.  The bad news is that finding the leak can be a real pain in the neck.  The first step is to turn off any running water pumps and let the pond stand still.  Mark the water level and watch to see if the pond is continuing to lose water at the rate it was before.  If the water level continues to drop, then you have a leak in the pond itself, but if it stops then you must have a leak in the plumbing or in the water feature.

3  Find the Leak

     a.  A Leaky Pond

If you have a leak in the pond itself then you may be able to simply allow the water to continue dropping down until it stops and then search the water line for holes in the liner, or cracks in the concrete.  This method of finding the leak has a couple of problems in that fish do not do well in standing water, especially on hot days, for long periods of time.  Secondly, the hole may be on the bottom of the pond, so allowing the pond to slowly dry completely out is usually not a great plan.  The first problem might be temporarily solved using aerators, but the second problem may require a complete draining of the pond and storing the fish elsewhere.

I know pond contractors who swear by the “Half & Half” method of finding a hole in a pond.  They will make sure all pumps are turned completely off and allow some time for all water movement to slow down to nothing, then drop one or two drops of Half & Half coffee creamer into the pond and watch which direction they move.  The creamer will slowly, very slow move in the direction of the hole.  This obviously will only give you the general direction of the leak, but at least it’s a start.

Beyond that finding a hole in the pond requires good old getting down and looking.  Occasionally a wet spot around the outside edge of the pond will give you an indication of where to look, but more often than not there will not be any wet areas.  Good places to look are around boulders near the edge of the pond, especially if mortar was used to hold the boulders in place.  Check areas that are seamed together or that have pipes passing through.  Also, consider what has happened to the pond lately.  If kids have been playing around the pond or if a dog has jumped into the pond lately then that may be a clue as the where the hole might be (and why the hole might exist).

     3b.  A Leaky Waterfall or Stream

First, look for obvious wet spots.  With the water flowing check the plumbing first, from where the pipe or tubing exits the pond until it comes out at the top of the waterfall.  Check all the fittings if possible to make sure they are watertight.  Then check any filters you have in line to make sure they are completely water tight.  Upflow filters at the top of the waterfall are sometimes a problem if the filter pads have not been cleaned regularly since the pads will stop letting water pass through and water will actually squirt up and over the back of the filter.  In the same way pressurized filters can begin to leak if they are not cleaned regularly and the pressure builds up to the point that water is pushed past the seals.  O-rings and gaskets also need to be replaced periodically or they can allow water to escape the system.  If you are able to check the hoses you should do so, since some types of tubing can become brittle and crack after a few years.

Assuming the plumbing checks out, next check along the edges of the water feature.  Occasionally liner can sag down and allow water to flow out.  Especially check spots where there are folds in the liner along the edge.  Just a little bit of dry soil in a spot where water is wicking up between folds will allow the soil to suck the water up like a straw.  A waterfall that is mortared into place may have cracks in the mortar just beneath or around the rocks, since some types of rocks will deteriorate at a different rate than the mortar, and many will expand and contract during cold and warm weather differently than the mortar.  Look for areas in concrete that have obvious cracks, and look for fine tree roots that could be starting to force their way through.  A loose boulder in the waterfall or stream that wasn’t loose before is a dead giveaway for a nearby problem.

If you just can’t find the leak in a waterfall you can try running a hose from your pump to the bottom of the waterfall, then checking to see if the pond is losing water.  Continue moving the hose up the waterfall by a foot or so, until the pond starts to lose water.  Once you notice water loss then you have a pretty good idea of where the leak is.  Two more reasons you could have a leak, and something to watch out for is:  a)bamboo is nasty stuff, and is the only plant that I have seen that is able to penetrate liner.  The new shoots come up out of the ground like sharp spears.  So if you have bamboo near the pond,  check there.  b)  Pack rats will eat holes in epdm liner.  I have not seen them do it in the pond itself (although I have seen muskrats do it), but I have dealt with several large holes in waterfalls.

4)  Fix that leak

4a.  A Liner Pond

If you have the hole in the liner, then the hard part is done.  A preformed, hard plastic liner pond or a polyethylene liner pond can really only be patched using a peel-&-stick universal repair tape.  Simply clean and dry the area around the hole in the liner, peal and apply the tape and then go over the tape with a roller to make sure any possible gaps between the repair tape and the liner are removed.

An EPDM liner is only slightly more difficult.  The only difference being that an EPDM liner requires a specific type of primer to be painted onto the liner where the repair tape is going to be adhered, and it uses a different type of repair tape.  A larger hole can be patched in the same way using a small scrap of liner taped over the hole using the same primer and repair tape combo.

4b.  A Concrete Pond

Concrete ponds are much more difficult to permanently repair.  Most often concrete will continue to crack once it has begun.  Patches and coating can slow down the process and give you at least short term fixes, however.  A minor crack can be sealed using a masonry crack sealer, which usually comes in a tube or bottle, or by using a hydraulic cement.  The hydraulic cement usually comes in a powder (I usually us FastPlug by UGL) and will mostly dry after about ten minutes, but will finish curing even underwater.

A more extensively deteriorating concrete pond can be coated with any number of products, and most contractors will have their favorite.  Generally they are going to be either rubberized coatings (Herco Products, CIM, etc), epoxy coatings (Pond Armor), or plaster based coatings (Sider-Crete).  With any of these products you will need to thoroughly prep the old concrete, including cleaning, filling in any pits or cracks, acid washing, and often using a primer.

So that is basically all there is to it.  Sound like fun? Probably not, but finding and repairing a leaking pond is something that many pond owners have to put up with in order to enjoy the lovely sounds of moving water.

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