Bentonite is the best pond sealer in the USA

The right solution to stop water seepage in ponds and lakes

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How bentonite helps seal your pond naturally

Sodium bentonite is a 100% natural mineral clay, formed millions of years ago from volcanic ash and transformed through many years into a clay with particular absorbent properties. It is now extracted and milled down to specific grain sizes, either powdered or granular bentonite and the powder is used as a pond sealer. Bentonite absorbs water, creating a sort of muddy substance that helps plug any holes. cracks or crevices in the ground.


The powdered or granular bentonite fills the crevices, gaps or cracks in the soil. Then it needs to be covered and compacted in order to expand inside an enclosed section. The expansion of the bentonite molecules will create a seal that prevents the leakage of water through the soil of the pond. It can be used to treat identified or isolated leaks (like holes dug by rodents or dam leakage) or to seal larger areas. It is one of the best options for larger ponds or lakes (1/4 acre plus).


Bentonite Sealer is easy to apply in either dry or wet ponds (ponds that can’t be drained). Fully safe for life, it is ideal to be used in ponds that have fish, any kind of plants and vegetation, or will be used as a source of water for livestock, wildlife or agricultural irrigation. A big advantage over rubber liners like EPDM or HDPE is that there is no puncture or tear risk involved.


clay liner

Using the correct method to apply the bentonite pond sealer is key for success. We can’t stress enough the importance of the correct product application. It is the difference between a full pond for years to come or headaches year after year.


When there isn’t a single identified area for the pond leaks, we recommend drying the pond, when possible. For dry ponds, there are 2 methods. The first one is the blanket method, which requires removing debris to create a surface as smooth as possible, removing about 6 inches of soil, applying the amount of sealant required in an even layer and then covering the layer of sealant with the soil that was previously removed. Then it is ready to slowly add the water in.


The mixed blanket method requires to rake or till 6 inches of soil and then apply the sealant as if you were seeding or fertilizing. Rake again to mix the bentonite into the ground and compact the ground. Remember to add the water in a steady flow to prevent disturbing the layer of product you just created.

Bentonite Clay Pond Sealer Application in a Retention Pond

Bentonite Pond Sealer vs Soilfloc

There are 2 categories of pond sealant products: active and passive. Bentonite is an active pond sealant, which means it interacts with the environment to create a watertight seal that prevents leakage. In the same category, we find polymeric pond sealants like Soilfloc, which makes them our best competition (yes, we respect them and we’re not afraid to talk about them).


Let’s start by explaining how polymeric sealant products work. The polymer molecule (which is called anionic polyacrylamide) is a man-made product derived from plants, that, as its name says, has negatively charged ions, giving the polymers ability to attract positively charged clay cations. So yes, they actually attract the existing clay in your pond for the sealing process! In combination with a man-made polymer. What do we think? Well, we think that if the clay alone can work for you, why use a man-made product? Of course, this depends on each particular case and while bentonite sealer might be best for some cases, soilfloc can beat us in other cases. It all depends on the customer’s project.

Polymer products were designed for wet applications, so bentonite pond sealer will always beat them if the pond is dry. If your pond has water, bentonite can still be a good pond sealer in several cases like when there are holes dug by rodents, for sealing dams or embankments and for identified isolated leaks.  Polymers usually come in parts, a format that requires you to apply part A and then, part B. With bentonite, you have a single application and that’s it. No parts, no complication.


Is there a better product choice between polymer sealants like soilfloc and bentonite pond sealer? We believe there is, but it will depend on your particular project needs and your personal interests. While polymer products may be required in some cases, if you are hesitant between these 2 types of pond sealant products give us a call. We will honestly tell you if bentonite is not the best choice for your project (yes, integrity is one of our core values).

bentonite pond sealer application
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Bentonite Pond Sealer can be used by:

  • Farm & Ranch Owners – For retention, fishing and recreational ponds.
  • Residential Developments – Retention and recreational ponds are part of residential construction since the 1970’s.
  • Municipalities & State Governments – Any requirements for retention, wildlife and fishing ponds can be served.
  • Golf Courses – Serving hotels & golf courses all over the country.
  • Businesses – Venues for social events can look idyllic all the time.
  • Homeowners – Suburban owners build and line their recreational ponds with bentonite.

Why purchase Bentonite Pond Sealer with Lonestar Minerals

Using the expertise of more than 50 years in the field, Lonestar Minerals has developed its own “formula” for pond sealer, using sodium bentonite as the only ingredient. We use a mix of different grain sizes, milled and packed at our ISO-9001 processing plant. We test each and every batch leaving our plant to guarantee its quality.


The mix of bentonite particles and granular bentonite allows us to take advantage of the properties of both grain sizes, helping reduce the amount of bentonite required per square foot* (*compared to other sources of bentonite clay for ponds).


We work with an extensive delivery network and can reach most states of the United States within 1-2 days. We have availability from a single 5 gallon bucket with 50 lbs of bentonite pond sealer up to full truckloads of bentonite for pond construction, delivered in paper bags or 3,000 pounds super sacks.


We pride ourselves in conducting our business with Integrity, providing truthful consultation services (yes, we will honestly tell you if bentonite is not the best solution for you) and operating under laws, legislation and policies. We value People, rather than things. Our main goal is to aid our customer’s success and to know our staff is proud to be working with us. Learn more about Lonestar Minerals in our About page.


Need help applying bentonite pond sealer?

We provide full service to fix leaky ponds and lakes. We’ll supply the necessary equipment, operators, and mineral to seal your pond and offer you a turnkey job.



[email protected]



[email protected]


Lone Star GTC, LLC

Texas Wholesaler Supplier for Bentonite Mineral
17595 Blanco Rd. Suite 200, San Antonio, TX 78232


What are the benefits of using bentonite as a pond sealer?

Sealing leaks or full ponds with bentonite is cost effective, non toxic, environmentally friendly and long lasting. It is quite easy to apply, although it is important to get it right in order for the seal to be effective.

How much pond sealer is needed for a 1 acre pond?

The short answer is between 30 and 80 tons of bentonite, to line the whole pond. That said, this is based on a pond that has measurements of 208 feet x 208 feet and 8 feet depth. It is quite a large pond, and the exact amount of sealant will depend on the type of soil of the pond bottom the more porous it is, the more product will be required to create an effective and long lasting seal. The pond sealer itself it’s an inexpensive material, so don’t be afraid to Request a Free Quote.

How much bentonite pond sealer I needed to seal a pond?

As an interesting fact, this is one of the most complicated questions to answer for our clients. The amount depends on several factors, like the type of soil, the size of the pond, the depth, the quality of the sodium bentonite, the purpose of the pond and the wildlife around the area.
Below you will find a small reference table depending on the type of soil and based on a maximum 8 ft depth. If the pond is deeper, you’ll have to add more bentonite per sqaure foot.
You can also visit our online Bentonite Calculator for a quick reference calculation.

Soil condition → Pond sealant amount per square foot
Rock or gravel → 3.0 to 3.5 lbs / sq ft
Clean Sand → 2.5 to 3.5 lbs /sq ft
Silty Sand → 2.0 to 2.5 lbs / sq ft
Sandy Silt 20% Clay Min → 1.5 to 2.0 lbs / sq ft
Clay Soil → 1.0 to 1.5 lbs / sq ft

Where to buy bentonite clay for ponds?

Important fact: verify when you’re buying that you purchase pure crushed SODIUM Bentonite, as there is also calcium bentonite and potassium bentonite and those don’t share the absorbant properties that make sodium bentonite a great pond sealant. Buy bentonite clay for ponds with Lonestar Minerals, your Wholesale Bentonite Supplier. Nationwide delivery at a great price per ton, ISO-9001 certified processing plant, ensuring great quality bentonite. Special mix-mesh formula that helps you use less amount of bentonite per square foot. Contact Us to get a free quote.

How is the bentonite pond sealer delivered?

We offer bentonite pond sealant by the full truckload, less than a truckload, by the pallet, bag, or by the ton.
We offer our products delivered at any of our warehouses. (Inventory always available). Our main warehouse is in Laredo, TX. We have a secondary warehouse in Wyoming, where sodium bentonite is mined. We also have warehouses in Eagle Pass and Bulverde, TX (11 miles north of San Antonio, TX.)
We can coordinate logistics delivery nationwide at a very competitive rate. We can ship directly from our Wyoming mines depending on your location and the logistics cost. We can coordinate delivery from LTL –  less than a full truckload order to an FTL full truckload order. Contact Us to get a landed price quote.
Our headquarters office is in San Antonio, TX.