Unfortunately pond leaks are a common problem
Their are many causes of water loss and some loss is a natural occurrence
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Water is in a constant state of flux. The terms infiltration, percolation, precipitation, evaporation and transpiration all apply. This essentially means you can't expect your pond to stay full of water without some top up from time to time
Of course there are many variables but I generally set a cap of about 2 inches per week of water loss for the typical pond with waterfall in the heat of Summer |
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We are all familiar with evaporation. Water turns into a gas and rises out of the pond. In some ponds this mode of loss can be significant. Emergent plants also contribute to this water loss by transpiration which occurs through the leaves
The type of rock you have in your pond also plays a role. Rock of greater porosity will absorb water and evaporate it more readily. The picture on the right illustrates how this rock has absorbed water well above the waterline
A pond in full sun you will lose more water than one in a shady spot. If your pond is in the open, subject to winds, you will lose more water than in a sheltered location. Waterfalls are also major contributors of water loss as water can splash out of the pond very easily. Geosynthetic underlayment is another problem if installed incorrectly. It can act like a wick and remove a tremendous amount of water if one end of it is in the water while the other makes contact with the soil |
Ponds lose water. Expect at least an inch a week in hot weather, possibly more if you have a waterfall and a lot of plants
If you are losing 2-3 inches a week of water you probably have a leak, but it is likely not significant one and prove difficult to find. It may or may not be prudent to attempt to fix the problem as the hole will be tiny with this small amount of water loss. It is likely better to set up an automatic refill or just top up your pond 1-2x per week. As most hobbyists would advocate a 10% water change per week, your tiny leak is forcing you to do this. Of course that is the optimistic viewpoint. You do have to make sure that the water loss is not structurally damaging and I would pay special attention to leaking ponds with large stone that do not have a] geosynthetic underlayment and b] a concrete collar for support
Also of merit is the fact that you may do more damage looking for an inconsequential leak ergo, it's sometimes it's better to just leave it alone
Remember, a small hole can be accountable for a large amount of water loss in the course of a week's time. These small holes can plug themselves over time. The bottom line is if you are losing a little bit of water and are unable to locate the leak, don't agonize over it |
Every season we fix quite a few leaks and most of them are pretty simple to spot. Don't panic if you are losing a lot of water, it will likely be much easier to find the leak if that is the case. Of course sometimes there is more than 1 leak ! Here are the troubleshooting steps we use to locate leaks:
Step #1 - Turn off your Equipment
Turn off any waterfalls, water features - all the pumps. Of course care must be given to the fish in terms of extra aeration and water quality. It is very important to mark your level and take notes in regards to the water loss. Date, weather, amount of water lost etc. will all be helpful down the road
The easiest way to mark you level is to hang a nut or other weighted object on a string from a perimeter rock. Have it just barely touching the surface. On the next day observe its location in reference to the surface. Because the pumps are all off, if no water is lost then you can conclude something is awry with the waterfall or other pump related feature(s). This is a very common scenario. You will have to closely scrutinize the waterfall setup and I often use a regular plant moisture meter to locate areas that are wet. If your pond is still losing water after shutting down the pumps, fountains etc. go to step 2
Step #2 - Let the Pond Drain until it Stops
You have eliminated the waterfall as the culprit. You must now let the pond drain to a point where it stops leaking . This could take a day, days, or even a week or two, dependant on what rate the pond is leaking and how far down the leak is. But the water should eventually cease to drop or show negligible loss from one day to the next. Again, you must take measurements and notes on a daily basis as you can easily forget and lose track of what is actually occurring. Now that the water has stopped dropping, scan the water line at the liner. Is there a skimmer along the waterline ? Some other perforation in the liner such as a jet ? 9 times out of 10 that is your problem. Examine and replace and/or repair as necessary. If you have examined the water line and there is nothing obvious, proceed to step 3
If the leak occurs on the rockline then you have entered a worst case scenario. In this circumstance a rock has likely cut the liner. At the stabilized level, you will need to locate the rock(s) that appear to be right on the water surface plane. If some rocks are above or below water, these are not the problem. Rocks whose bottom is just barely wet need to be removed and the liner underneath checked. You can also dig sump holes every 3-4 feet. 8" diameter and 1.5 feet deep, they will collect water if the pond is leaking close by. This narrows down your search quite drastically. Still haven't found the problem read on...
Step #3 - Examine the Liner
You now have to get in your pond. Carefully move around the perimeter taking a very close look at the liner. Your face needs to be 6 inches from the liner to really examine it. Remember, it does not take a very large hole to loose a lot water over time. If you can't find anything then the next step is to raise the water about 1 inch, again making notes of the levels. You can now perform a milk or ink test
This test involves using an eye dropper or syringe full of milk or ink or even potassium permanganate if you like. These liquids have different densities to water and will form clouds. Squirt a small amount out just below the surface and right into the liner and observe the clouds. Move around the perimeter and if you have a leak, you will notice the clouds of your chosen substance moving in little jets or streams out of your pond
Step #4 - Electronic Leak Detection
Although electronic Leak detection is not foolproof, it can work in certain situations. A current is introduced into the pond (harmless to fish) and a ground is placed outside of the pond. A detection wand is used and locates with a tone where the current leaves the pond (making its way to the ground in the soil)
Step #5
A fresh set of eyes
Sometimes a fresh pair is what is required to locate the leak - it is very easy to get focused on a red herring. Experience is also a huge factor. I had a client who had searched and given up on finding his leak. When I arrived I asked all the preliminary questions. It took me less than 10 seconds to find the leak once I actually started looking - it was under the very first rock I moved. That was a refreshing and amusing change - its usually just not that easy
Final Comments
Finding a leak can be a long process. Be patient. Take accurate notes as to what troubleshooting was done and what conclusions are drawn. Did it rain? How much? Most of this preliminary process needs to be completed by the homeowner before we arrive
case study
Sometimes troubleshooting these problems can be very very tricky. As just one example, I visited a small pond that was losing water. I asked them to let the water level stabilize and then I would stop by. When it did, the water level was just below the skimmer - a red flag. Very compelling evidence was the fact that their was sunken ground behind the skimmer. I also noticed that the weir door of the skimmer was incorrectly installed as it was upside down. It seemed obvious the skimmer was leaking - or so I thought
After removing and reinstalling the skimmer flange and weir I was confident the problem was resolved. But surprisingly, it was not. The pond continued to leak. After a couple more visits and much observation by the clients, the ultimate problem was a hole in the liner behind the waterfall and/or water deflection by the waterfall out of the pond. I had checked for deflection using a flashlight behind the liner and falls but could find none. Only after I ripped out the waterfall rock, glued the very small hole and let the waterfall run with no rock (so that it dropped right into the pond) did it stop leaking. The moral of the story - it is easy to be fooled if you don't have your wits about you
Overall, if you think logically and use the process of elimination, you should find any leaks
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Once you locate a leak, you still need to fix it properly or the problem will persist.
We often arrive at a site to find patches in place that are not properly affixed or of the wrong material. The key is to spend the time cleaning, sanding and drying the leak area before you apply the proper rubber patch. Preparation is everything, sticking the patch on is the easy part
We also carry with us and advocate the use of a hair dryer to make the liner dry, supple and warm. Expect to spend at least 20 minutes repairing a small, single patch hole. If not, you will likely revisit the problem |
1) Thoroughly clean and dry the area around the hole
2) If you have it, liner prep can be sprayed on
3) Apply liner glue brushing until it becomes tacky
4) Evenly press a piece of liner tape over the leak
* double patching is a good idea
5) Roll the patch with a steel roller
6) Liner Caulk can be applied around the edge of the patch
See the liner taping page for more detail - the process is the same
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