Learn more about Pond Liner

  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 by Firestone 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! Firestone PondGard has a Limited Lifetime Warranty.

  1. 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.

  1. What does “FISH SAFE LINER” mean?

Firestone PondGard 45 mil EPDM 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 Firestone liner produced. In the history of Firestone brand pond liner no fish has EVER been determined to have died from exposure to PondGard liner.

  1. CAN I USE ROOFING Liner for my pond? / What is a toxic pond of death?

Sure you can……as long as you don’t mind dead fish! Roofing liner is very similar to PondGard pond liner. Unfortunately, roofing material is made of ingredients based upon current market prices. Sometimes it is made with ingredients the same as “fish safe liner” sometimes it is not. If you get a batch of material that is not made with “fish safe ingredients” you could end up with a toxic pond of death. Roofing material is often made with harsh ingredients such as arsenic that can sicken or kill your fish. If you install unsafe liner material in your pond you will soon see the fish moving around very lethargic and they will have a loss of apatite. At that point your fish will die and there is nothing that can be done about it.

  1. WHY DO I NEED UNDERLAYMENT? / Can I use newspaper or old carpet instead?

To answer those questions we need to know what exactly underlayment is and what it does. A proper underlayment is considered a “non woven Geotextile” That is a fancy term for saying it is a really tough material that is lightweight and easy to work with.

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!

  1. 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 Firestone PondGard 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 foot 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.


The Design it All online tool allows you to build out your custom water feature design and automatically calculate the necessary liner size, pump, and volume! Build your dream design today and take the guess work out of pond building!


  1. What sizes does Firestone PondGard liner come in?

Great question! Firestone Pond liner comes in lengths up to 100 foot in the following widths: 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 foot. This means the smallest size you could buy is a 5x5 and the largest size available is a 50x100.


  1. Is there a warranty on Firestone PondGard liner?

Yes there is. Firestone stands behind their product for Limited Lifetime Warranty. To obtain the warranty the liner must be installed to Firestone specifications which include the use of a protective Geotextile underlayment. At Graystone Creations we have learned a great deal about Firestone quality control in pond liner production. Each roll of liner is run through a laser that measures irregularities in material and seaming. Nothing gets out of the factory in less than premium condition. While obtaining certification to install Firestone brand Pond liner Graystone Creations has had the opportunity to learn about Firestone warranties and procedures. It was brought to our attention that only one section of Firestone liner has ever proven to be defective and that was on a seam where two rolls joined.

If you feel at any time your properly installed Firestone PondGard liner is defective Firestone will ask you to immediately send the questionable section to them. They will fully inspect the material right down to the microscopic level. They will work with you to determine how the liner was installed, if underlayment was used, if roots pushed through into the pond or if the liner was cut or punctured by any foreign object and much more. It is Firestones greatest pride to manufacturer a superior pond liner and every effort will be taken by teams of scientists to determine what caused the failure and how to prevent similar failures by proper installation.

Click to view Firestone's Limited Lifetime Warranty Guarantee

  1. How can I tell I am really getting Firestone PondGard liner?

Great question. Most rolls of Firestone liner leave the factory with periodic Firestone PondGard fish logos on them. It is possible to receive a small enough section of liner that you may miss one of the marks but if you ever have any doubt just ask. NOTE: Over the last couple years I have occasionally seen rolls arrive from the factory without the Firestone logo on them but that is pretty uncommon.

  1. 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!

  1. 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 Firestone liner.

  1. Why is Firestone Pond liner so expensive to ship?

Firestone 45 mil EPDM PondGard Pond 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.