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The pond liner is the foundation of your pond and the selection of the liner and the correct installation are crucial to having a long lasting leak free pond. Customers with earthen ponds often use Pond Seal for both the liner as well as for stopping leaks. Concrete ponds can be sealed permanently with Pond Amor/Pond Shield.

Ponds wishing to utilize a "rubber liner" system are the most common type of installation for consumers. The use of Firestone 45 Mil EPDM pond liner is a terrific way to get your pond off to a great start. Using the protective underlayment is ALWAYS recommended as it increases the puncture resistance of the pond liner by 400% and is required for the Limited Lifetime Manufacturers Warranty.

Pond Liner, Underlayment, Pond Shield & Pond Seal


Pond Installation Tools



Pond Liner Information and Step by Step Installation Videos



Fish friendly - Pondgard is based on EPDM synthetic rubber, a highly flexible stable material that's not only long-lasting and easy to work with, but safe for fish and plant life.

Highly flexible - stays flexible in a variety of temperatures- from -40 degrees F to 175 degrees F- enabling it to be installed year-round. And unlike some other liner materials, Pondgard contains no plasticizers which can embrittle with age and cause cracks or splits in the material threatening fish and animal life.

Design versatility - can easily be shaped to fit the unique contours of your pond giving you much more design creativity. Multiple membrane panels can be quickly and securely seamed to accommodate larger pond lining applications and unique design elements such as waterfalls.

Weather resistant - shows outstanding resistance to the harmful effects of ultraviolet radiation (UV), ozone, and other environmental conditions- important characteristics, especially along the water line of the pond where the liner can be exposed.

Extreme durability and high elongation - EPDM has a characteristic that enables it to conform to objects in the subgrade. Pondgard will stretch over exposed rocks and tree roots.

Look for the Firestone Pondgard name, it is a mark of quality and confidence for a durable, beautiful, fish-friendly pond.

View Liner INSTALLATION VIDEOS to see 22 different Videos of liner installation and techniques.

Learn more about PondLiner

1. What does EPDM mean and why should I care?

EPDM is an abbreviation for Ethylene Propylene Diene Monomer. If you are a chemist you are probably thinking “WOW! I wish I would have thought of that”. For the rest of us it simply means this is some really high quality liner that is meant to last for years. In fact, testing has shown this liner to degrade only ½ mil per year when exposed to direct sunlight. This means that on average a 45 mil liner will still be around nearly 90 years from now!

2. What is 45 mil liner?

45 mil stands for the thickness of the liner material. It is 45/1000 of an inch thick. That may not sound like a lot but this super sturdy liner is the choice of professional pond installers and consumers all over the world. To give you an idea of the outstanding strength of this liner consider that 3.2 square foot of 45 mil liner will weigh 1 full pound.

3. Why is EPDM liner better than a cheap PVC liner?

Excellent question and one that is not asked enough! Lets talk about PVC liner first. PVC liner is super cheap and really easy to work with since it is so thin. PVC liner is lightweight compared to heavy duty EPDM and often costs much less to ship. Sounds good right? Now the downside. Liners containing PVC are made with plasticizers to keep them flexible. Over time, or when exposed to the sun these plasticizers leach out of the liner leaving it brittle. In as little as one year a pvc liner can be brittle enough to split open under the weight of your pond water and one day you look out to find an empty pond. It is possible to cover the PVC liner with enough rocks and dirt to prevent the sun from reaching it and this will give you a few more years of use.

The question you should be asking yourself is whether you wish to make the cheapest pond possible or whether you wish to build a pond that will last and be enjoyed for years to come. Building your pond with the cheapest liner possible is like building a house with foundations made of sand. It may look nice for a while but in the end you will come to deeply regret spending the few extra dollars to do the job right.

4. What does “FISH SAFE LINER” mean?

This 45 mil EPDM pond liner is manufactured to be fish safe. That means that the ingredients used in making the liner are perfectly safe for your fish. The same ingredients are used with EACH AND EVERY batch of liner produced.

Roofing liners SOMETIMES use ingredients that are fish safe, and SOMETIMES they do not. Apparently the market price of these ingredients changes quite a bit. Sometimes you get the good stuff, sometimes you don’t. It is your choice which pond liner you choose but if you stock your pond with a few hundred dollars worth of fancy goldfish or a few thousand dollars of imported Koi I think you will agree bargain pond liner may not be such a bargain after all.


Underlayment has only one job and that is to protect your pond liner. 45 mil Pond liner is very strong and puncture resistant but it does have its limits. Using a 7oz thickness of underlayment can improve the PUNTURE RESISTANCE of your pond liner by 400%. Strangely, using a thicker underlayment will not significantly increase the protection to the liner but using a thinner one will greatly reduce your protection.

“I want to use newspapers for an underlayment.” Great, go right ahead. Just make sure you test the thickness that you need by stacking enough WET newspapers over a sharp rock that it does not poke thru when you put 20,000 lbs on top of it! The average 2 foot deep pond that is 11x16 foot will have enough water in it to exceed 10 TONS. That’s over 20,000 pounds of water in your pond. If you use newspapers as your underlayment you better stack them about 1 foot thick. That’s a lot of Sunday papers folks!

“I want to use sand for an underlayment” SEE ABOVE. Unless you OWN the beach you are getting the sand from it is a BAD and expensive idea to try and put enough sand down to protect your pond liner from rocks hidden under the surface. These rocks will emerge over time as the HUGE weight of your pond presses down on it.

“I want to use old carpet for an underlayment” Got allergies? No, well you soon will have. Yes, then stay away from your pond all together as it will soon make you sick. Look folks, saving money is my favorite past time but doing so at the risk of my health has never been high on my list. Carpets are NASTY, DIRTY, BACTERIA FILLED MOLD ATTRACTORS! And that’s when they are dry in your home. Now take this same filthy used rag and put it under your pond liner where it will sit wet and moldy for the next 10-20 years. In this case your fish will be fine but as far as the people around the pond, their health is in your hands.

Save money when it makes sense and spend money to ensure your family and friends enjoy your new pond without the need for allergy shots!

6. How much liner do I need?

Liner calculations are not as hard as they seem. There are lots of handy formulas around to help you determine the exact amount you need but with most ponds a the following guide should be most useful.
  1. Take the max length of your pond and write it down. “lets say 9 foot”
  2. Take the max depth (not the average depth) and double that. “2 foot deep would be 4 foot” If the liner goes down into the pond it must come back up! That is why you double the depth.
  3. Add 2 foot to the total (one foot overhand on each end to anchor the liner)

This gives you a required length of liner as 9+4+2=15

Use the same calculations for the width. Example: 7 foot wide (use the same depth) would give you a required width of 7+4+2=13

YOUR REQUIRED SIZE would then be 15x14. As liners are sold in 5 foot increments you would purchase a liner that was 15x15

Special Liner Sizing Notes:

  1. When attaching a waterfall filter that will be elevated above the pond, you will need additional liner. If you have a 4 feet tall waterfall then you will need an additional 4 foot of liner on that side.
  2. When constructing a larger pond, you may need to use additional liner on each side to anchor the pond. For large ponds consider using 2 foot of liner on each side and for extremely large pond you should call for assistance.

7. What sizes does EPDM Pond liner come in?

Great question! Pond liner comes in lengths up to 100 foot in the following widths: 5, 10, 15, 20, 25, 30, 40, and 50 foot. This means the smallest size you could buy is a 5x5 and the largest size available is a 50x10.

8. Do you have other Liner Accessories for sale?

Yes we do. From seaming tape, to pipe boots, repair kits and primer, Graystone Creations has a full line of the products you need to install and maintain your pond liner.

9. My liner has footprints on it. What happened?

We walked on it! The size of the liner ordered will depend upon which roll we cut your order from. Very large liner sizes require both unrolling of the liner in our warehouse and the cutting and refolding of the liner so we can ship it. Sometimes it takes several workers to fold and roll large sections of this very heavy liner and it gets stepped on. Yes the size 13 print is my own!

10. There are some dried silver looking specs on part of my liner. Is that paint?

Nope! Occasionally the curing / drying process will leave some silver colored spots on the liner. This discoloration is minor and in no way effects the use or quality of the liner.

11. Why is Pond liner so expensive to ship?

45 mil EPDM liner weighs about .30 pounds per square foot. This means a 20x25 foot (500 square foot) liner will weigh 150 lbs. There is no cheap way to ship this liner. Liners over 150 lbs ship by freight and require a signature upon delivery. Freight orders will require 2 or more people to unload and transport the liner to its location. VERY large liners may require as many as 8-10 people to move into position in your pond.
Graystone Industries ships most pond liner from a warehouse in Franklin NC. Walk in customers are welcome Tuesday thru Friday. Pond liner orders to the west coast generally take 5-6 business days to arrive.

12. I see what appear to be seams in my pond liner. Did you seam multiple sections together?

Nope! Manufacturers add a factory reinforcement seam every 5-10 foot depending upon the manufacturer. This reinforcement is the strongest part of the pond liner and designed to ensure the liner does not fail under the incredible pressure of the weight of the water pressing down on it.

Thanks for your interest in the liner and we wish you the very best on your pond or water feature project. Graystone carries over 3000 pond supply items so please let us know if we may assist you in saving you money with a complete package or combined shipping!

Written by: John Olson Owner & CEO of GraystoneCreations.com


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