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How To Find A Leak In Your Pond In 2 Steps

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

A pond is a thing of beauty in any garden, creating natural landscaping and a place to relax.

A man made pond can also take a lot of work to build, laying the foundation, getting the soil just right and then adding fish or flora to the mix – so when a leak strikes it can be devastating if left untreated.

Often, a great loss of water can have deadly consequences for any wildlife in your pond and completely wreck the ecosystem you’ve worked so hard to create.

Fish and other wildlife need a steady water level maintained, so it is crucial that any leaks are found and repaired as soon as possible.

Thankfully there is a sure fire way to not only tell if your pond is leaking, but to repair and even help prevent any water leakage in the future!

So, whether you have a leak in your pond’s liner (see also ‘How To Repair Pond Liner That Is Leaking‘), concrete foundation or clay foundation, with the help of this article, you’ll be able to tell in just a few simple steps.

No need to leave it up to chance, with the handy guide in this article, just simply follow the steps below and get started!

Is My Pond Leaking?

Your pond may often seem as though it is losing water, ponds naturally lose water through the process of evaporation.

The amount of water that a pond will lose is down to a number of factors, including the climate conditions – high temperature with a lot of sunshine and a low humidity rate, will lead to more evaporation.

On the other hand, low temperatures with overcast conditions and high humidity will lead to a lower evaporation rate. 

Evaporation is the process by which water changes from a liquid to a gas and is a natural part of the water cycle.

You can, however, estimate what your local evaporation rate is through an evaporation guide found online or by getting in touch with local meteorological stations, who often have that information on record. 

There can still be a substantial amount of water lost through evaporation, so to avoid this, it might be worth installing an auto valve in your pond skimmer.

This will help to ensure your pond’s water levels remain at the desired level, without having to physically fill the pond back up yourself.

If your climate is not simpatico with evaporation, and you feel the amount of water lost is too significant to be due to evaporation, you may have a leak.

Luckily, in this article we will not only tell you how to identify if you have a leak but below you’ll find ways to repair different types of leaks and how to prevent any leakage in the future. 

How To Find The Leak

Once you have established there is a leak in your pond, you’ll need to deal with it quite quickly to avoid losing any fish or flora. Follow these simple steps;

1. Inspect The Edges For Overspill – Often, rather than a hole in the pond liner, the reason for dramatic water loss will be overspill along the edges of the pond.

Overspill is especially common if you have a water feature like a waterfall or stream (check out our guide on building a backyard stream). It is helpful to also look out for areas where your liner may have settled or any landscape rocks have shifted. 

So, you will need to firstly fill your pond up to the desired level and then inspect the edges for any water spilling over. A common place for overspill is any tight turns in streams or to the left or right of a waterfall.

Checking the outer spaces and perimeter of the pond can be helpful as any damp patches or water pooling can be an indicator of overspilling.

2. Shut Down The Pump –  If you’ve checked, and overspill definitely is not the cause, then it’s time to look at the pond itself and the surrounding equipment.

Shutting off the pond’s pump and turning off your auto fill valve (if you have one) is the most important step in telling you where the leak is. 

If your pump is turned off and the pond is still experiencing water loss, then the leak is probably in the liner or the actual foundation of the pond.

The water will leak out  until it hits the spot where the tear or crack is. 

If you’re still not able to find where the leak is, you can try using pond dye or even using the milk method to find the leak.

This method involves putting dye or milk into a squirt bottle and spraying it into the water, at the edges of the pond.

The dye/milk will cloud the water where there is no hole and flow towards the leak, if there is one. This is a particularly effective method and has the added bonus of being very affordable. 

However, if your pond still held water while the pump was off, then the cause of the leak is most likely in the equipment or plumbing.

This is why it’s so important to check any plumbing or external components, such as your skimmer box, external pond filter, waterfall box etc. 

Water leaks are usually found in the pipe’s fittings and components, so it is a good idea to start there.

→Important to Note: Results may not be seen straight away. It may take a day or two, so if you have fish in your pond, you will need to run a pond aerator (see also ‘Best Pond Air Pump & Aerator‘) while the pump is off, to ensure they get the oxygen they need in the meantime. It may also become necessary to remove the fish from the pond if the water level drops too low. 

How To Repair The Leak

How To Find A Leak In Your Pond In 2 Steps

A Liner Leak

There are a multitude of ways to fix a hole in your pond liner and stop water leakage. Of course, the method you use will depend on the exact size of the hole. If the hole is less than 5 inches, it is possible to use an underwater sealant or a patch kit. 

If you’re using an underwater sealant, it’s important to follow these steps;

  • Make sure the surface of the liner is thoroughly clean. 
  • Apply the sealer directly to the surface of the tear
  • Allow it to cure or harden for 24 hours minimum. 

Remember, you do not need to drain your pond in order to use the underwater sealant. I can still be applied and will cure in the water.

If You’ve decided to use a Patch Kit instead, you can use the steps below;

  • Make sure you clean and wipe the area where the tear is with a solvent wipe.
  • Scrub and dry the damaged area with a dry scrub brush.
  • Remove the release paper from the patch and apply it to the tear.
  • Using a seam roller, roll over the patch to ensure it’s tightly bonded.

A Concrete Pond Leak

If you have finally identified where the crack is in your concrete pond, you’ll need to seal it with a non toxic pond sealer. 

  • Prepare the surface where the crack is with the sealer as directed by the specific instructions for the sealer you are using. 
  • You may need to mix the sealer with a hardener as well. 
  • Apply the sealer carefully.
  • Let the sealer dry, this usually takes about 24 hours to fully harden or cure. 

A Clay Pond Leak

For ponds with soil or clay foundations, often found in farm ponds, it is recommended to use bentonite for sealing ponds. Sodium bentonite is a natural clay that expands up to 15 times its size when exposed to water. The expansion fills the cracks in the foundation of the pond and prevents any further water leakage in the pond. 

  • Read the manufacturer’s directions carefully. The pond may need to be fully drained to below the damaged area.
  • Apply the bentonite clay as per the stated directions. 
  • Refill your pond to the level you desire and check for any leaks to ensure the cracks are fully sealed.

How To Prevent A Leak

  • Using a high quality pond liner will almost always save you the hassle of repairing a leak as they are so sturdy you’re likely to never get one! 
  • Sealing your pond foundation with a layer of pact clay blanket can reinforce the bottom and help to prevent leakage.
  • Regularly checking for tree roots around the pond’s perimeter, to ensure that none are growing under the pond’s edge and causing overspill.

Frequently Asked Questions

Is It Normal For A Pond To Lose Water?

Yes, through evaporation, depending on the climate conditions, your pond can lose up to 1 to 2 inches of water per week.

This is completely normal and other factors, like location, time of year, pond size and weather can affect the rate of evaporation and therefore, how much water your pond loses. 

What Can Cause A Pond To Leak?

There can be many things that cause water leakage in ponds. These include, areas of sand or gravel that were not properly covered with soil during construction may eventually leak.

Leaks may also occur around the pond banks or on the pond dam due to tree roots or muskrat holes. 

Does Rainwater Affect Ponds?

Rainfall is generally a good thing for ponds as rainwater deposits certain nutrients in the pond and is excellent for any wildlife.

However, too much rainfall can deposit too many nutrients in the water and overload the system before it can filter through the nutrients.

It can also alter the pH level and the water hardness, which also has an effect on the pond’s wildlife. 

How Do I Maintain the Water Level In My Pond?

Turn the water on to a slow flow rate. Ponds lose water slowly by evaporation and a slow flow rate from a garden hose is enough to resupply any water lost and control the level in your pond.

Install the float valve in a stable location at the edge of your pond and adjust the valve to the desired water level

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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