Bentonite: A Natural Solution To Sealing Ponds

Do you own a fun and relaxing pond? Surrounded by beautiful plants and decorative stone-laden pathways, ponds can add life to your backyard or front lawn. It is most certainly a place wherein nature and homeowners/guests can coexist in peace. 

Although having your fish pond can be wonderful, it can easily turn into a migraine-inducing ordeal if it starts to spill or leak. If you find yourself constantly refilling your pond or notice that the surrounding area is soft, damp, or partially submerged, you likely leak your pond. 

Similarly, ponds can be a menace in case there is a leak in the pond made for the use of the community. The right sealant can be a godsend for all your pond leakage problems. 

Why Do Ponds Start To Leak? 

It is a common occurrence for your pond to lose water to evaporation in the summer season. Your pond’s water level might normally drop several centimeters daily during severe heat waves. It is also common for newly constructed ponds to have some amount of leakage. But if your pond loses copious amounts of water consistently, you must find the underlying cause. 

Here are some reasons why you have a leaky pond: 

  • Poor site selection
  • Erosion of the pond liner
  • Holes/cracks in the liner
  • Failure in pond repairs
  • Poor pond construction
  • Plumbing issues
  • Presence of the wrong plants
  • Damage from burrowing animals

Selecting a poor site is often the result of insufficient preliminary site checks and is an easily avoidable situation. You can avoid improper construction just as you can avoid the growth of trees and shrubs that develop root systems that undermine the dam.

Sometimes a poor site has to be used for ponds if there is no other choice and there is a dire need for water. If so, the original pond design must include plans for reducing seepage by sealing the pond bottom. 

To prevent excessive seepage, reduce the permeability of the soil to a point at which losses are insignificant or at least tolerable. The method depends largely on the proportions of coarse-grained sand and gravel and fine-grained clay and silt in the soil. Finding pond leakage issues can take time and effort. Many of these issues can be fixed, but it’s crucial to find all these issues before you can start reparation work. 

Why Is Pond Sealing So Important? 

Before we dive into the details, we must answer this important question: Why is pond sealing so important? Imagine filling a new pond with fresh water and then seeing it go dry within a few weeks. A pond that leaks again and again is super frustrating for the owner. Pond sealing is a science and if you are not following this it means you are going to waste your investment and pond. 

Pond sealing helps ensure that your pond stays impervious. It helps to put a stop to leaks, avoid water wastage, and keep the pond’s water level right. It can help to avoid damaging the delicate ecosystem of your pond, help conserve water resources, and avoid harming surrounding areas. 

The tedious and difficult job of sealing a pond can be time-consuming and expensive. There are different drawbacks to using common sealant for pond sealing. One of the key reasons why pond sealing is so important is water life security because the pond probably will be full of water and algae or plant growth which a leakage in the pond can harm. 

Why Use Bentonite For Pond Sealing? 

Sodium Bentonite is also known as “high-swell” clay. It possesses many remarkable qualities, because of which it becomes greatly useful in sealing ponds and withholding water for the longest period. 

Bentonite changes from a powder to a muddy gel when mixed with water. This gel fills the cracks and pores in the pond floor, creating a natural and very resistant barrier that will keep the water in the pond. 

You can use Bentonite for sealing dry or full ponds, even in ponds with plants and fish. It is volcanic ash that is a 100% natural earth material that does not involve other chemicals or hazardous substances. It does not contaminate the water. It is eco-friendly and safe for fish, plants, stock, and swimming. 

Bentonite pond sealer, a natural clay product, chemically attracts to itself and swells up to 12 times its dry size when moistened. It also makes an excellent liner for new pond construction. 

Sodium Bentonite can help your pond retain its water levels and reduce the rate of water seepage significantly. It has the property of quick adsorption. It is a cost-efficient pond sealing element. 

It is naturally erosion-resistant and lasts for an extended period. With re-swelling nature and re-hydration, particles are easily dispersed in water and obtain high absorbency. The bentonite pond sealing should be applied evenly across the soil using a seed or fertilizer spreader. 

How To Use Bentonite For Pond Sealing? 

There are 3 different methods of using bentonite for pond sealing. They are as follows: 

  • The Blanket Method: 

This is probably one of the most successful and popular methods. But for this method to be applied, the pond must be still under construction and be unfilled. In the case of using this method on an already constructed pond, it has to be emptied and dried out. 

The next step is to remove any rocks, vegetation, and trash from the bottom of the pond. Then remove 4 to 6 inches of the soil from the pond bottom. In the next step, find any holes or crevices and fill them with a mix of five parts soil to one part Bentonite. Then the area needs to be smoothed by using a roller. 

The required amount of Sodium Bentonite is then evenly spread on the area while ensuring that there are no thin or bare spots. This ensures complete coverage and proper sealing. After this, carefully spread the 4 to 6 inches of soil removed earlier over the bentonite layer while ensuring not to disturb the bentonite layer. Finally, the soil is compacted by using a roller or temping plate. 

You can wait for some days for the bentonite to swell before filling the pond with water again. But you can fill it out immediately if you want to. Just ensure you are using a gentle water flow to avoid erosion of the soil and bentonite layers. 

  • The Mixed Blanket Method: 

The mixed blanket method is similar to the blanket method. The key difference here is a layer of a mix of Bentonite and soil is used instead of using only Bentonite. The first step is to make sure the pond is empty and sufficiently dried out. 

The next step is to remove all debris, vegetation, and rocks from the pond bottom. Check the pond bottom for any holes, cracks, or crevices and fill them with a mixture of one part Bentonite to 5 parts soil. 

Next plow, till, or disc the top 4 to 12 inches of soil. Then apply the required amount of Sodium Bentonite to the soil in an even layer by using a fertilizer or seed spreader. Mix the Bentonite with the top 4 to 6 inches of soil by discing, tilling, or hand raking while ensuring that no bald spots are left. Multiple passes over the area are recommended. 

Finally, using a roller compact this mix of bentonite and soil. Adding some water might be needed to ensure complete compaction if the soil is too dry. Be careful when adding water back to the pond. Use gentle water flow to prevent disturbing the bentonite-soil mix. 

  • The Sprinkle Method: 

In the following scenarios, the sprinkle method can be used for pond sealing: 

  • Emptying or draining a pond completely is not possible or not feasible.
  • Leaks are relatively smaller and are isolated from each other. 
  • Leaks need to be fixed quickly. 

This method is not as efficient as the blanket method or mixed blanket method. This is due to difficulties in uniform and accurate placement of the bentonite and the pond bottom may include debris such as trash, vegetation, logs, rocks, etc., which may prevent sufficient coverage. 

Start by clearing out the pond bottom of any logs, vegetation, or rocks to increase the chances of success of the sprinkler method. Then sprinkle the required amount of Sodium Bentonite on the surface of the pond water and let it fall to the bottom of the pond. 

The bentonite particles will reach the bottom and then swell to fix the leaks. You will require more quantity of Sodium Bentonite than the other two methods. Sodium Bentonite will cause cloudiness in the pond water, but it will be cleared within a few days. 

Why Use CMS SEAL? 

At CMS, we bring you top-quality bentonite material in a quantity to suit your needs. The following are a variety of characteristics that make this such a great solution to all your leaky pool issues:

  • Eco-friendly
  • Quick adsorption
  • Cost-efficient
  • Reduction of water pollution
  • Strong, impermeable layer that prevents leaks
  • Purifies water
  • Safe for aquatic animals and vegetation
  • Seals the lower bed of the soil to reduce seepage
  • Convenient to mix because of its dispersed nature

To learn more about how sodium bentonite can help with your leaking pond, visit us at or fill out this form stating your needs to get an instant quote. 

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