Pond Liner Answers To The 6 Questions You Need To Ask

You Can Find Answers To Most Of The Pond Liner Questions You Have
Messing with pond liner to make it better

Pond liners are the safety net for your yard, anything living in your pond, and ultimately your wallet. It’s what keeps the water in your pond and without it, well, backyard ponds would be a lot different. This is why it’s important to get a quality liner and make sure it stays in good condition.

Here are the answers to pond liner questions pond owners (and future pond owners) are asking.

Pond What-Now?

“So, you’re telling me that koi ponds have to have one of these things?”

Brian is looking at Denise in surprise. She did just tell him that koi ponds are lined with something called a pond liner that helps keep all the water in it.

He just thought people dug a hole and put water and fish into it.

Man laying down in pond hole to show just how big it is

She goes on to tell him it’s one of the more important parts because it helps keep all the water in place. Without it you’ll end up having to use one of these 3 water drainage solutions or you’ll have a swamp for a yard. That’s why they, or whoever installs their pond, need to use a quality liner.

Brian doesn’t want either of them to have to deal with a bad liner. He decides to do some independent research on liners so he can tell the good from the bad.

Here’s what he finds.

Which Pond Liner Is Best?

Fish safe 45 mil EPDM (ethylene propylene diene monomer) is a popular pond liner choice for many reasons. It’s very flexible which makes it easy to lay down and forms better to the tight corners and shelves in the pond hole. It’s temperature resistant from -40 to 175 degrees Fahrenheit and it’s weather resistant.

Newer and bigger and safer pond liner

Brian raises his eyes in wonder at the temperature range. Looks like this stuff is the real deal so he needs to look into EPDM liners a bit more.

He also reads there are PVC and preformed liners, neither of which sound as good as the EPDM liners so far. They aren’t as flexible or durable so he doesn’t see a point in looking into them. Instead, he looks up more about EPDM and rubber liners.

What Is EPDM Pond Liner?

EPDM pond liner is made from M-class synthetic rubber. The M refers to its classification in ASTM standard D-1418; the M class includes rubbers having a saturated chain of the polymethylene type.

In other words, it keeps water in, won’t poison your pond or yard with toxins, and doesn’t damage easily.

Brian only understood the last sentence, which makes sense because he isn’t a liner expert. As long as it does a great job and doesn’t hurt anything that’s all he needs.

How Long Does It Last?

EPDM and rubber pond liners, in general, can last upwards of 30 years. Plus they aren’t too expensive to repair if they get torn by digging or tree roots. Other liners can last anywhere from 20 years to having a life-time guarantee.

Pond liner for small pond

Brian thinks 30 years is plenty of time, plus easy and not-too-expensive repairs sound great. Speaking of repairs, how do you fix it if a tear or hole happens?

How Do You Repair Liner?

Small holes can be patched with primer, liner adhesive, and a liner patch or piece of cover tape. Larger holes usually require you to get a new liner.

Laying down the liner for building a backyard stream

You can repair a pond liner by following these 5 steps:

  1. Empty your pond so the water level is 1 foot below the hole
  2. Clean 4 inches of liner around the hole
  3. Prime the hole
  4. Cut the patch so it’s round (corners fray and peel up)
  5. Apply patch

Brian nods to himself. He didn’t think it would this easy, he can probably do it himself. The cleaning part is interesting though, how does one clean it?

How Do You Clean Pond Liner?

The short answer is you don’t clean your pond liner because you don’t need to. Algae and bacteria grow on it and promote a mature, healthy ecosystem. If it starts looking bad then something else is wrong besides the liner being unclean.

Large pond with liner

Brian thinks this is good to know. He wouldn’t want to hurt his pond instead of helping it. Now he just needs to find out sizing.

What Size Pond Liner Do I Need?

Measure the longest length and width of your pond along with how deep the deepest part is. Then use these equations: max length + (2x depth) + 2 x 0.15 meters = total liner length and maximum width + (2x depth) + 2 x 0.15 meters = total liner width. Then multiply the two numbers to get how many meters of pond liner you need.

Brian’s a little confused by the math so he scrolls down for more details.

Large pond with liner
Photo by Koi Acres – creative commons license 3.0 unported

You’ll want to do two times the depth because the liner has to go down one side and back up the other. The .15 meters is for overlap because you always want some extra liner. 

Now To Start Looking For A Pond Contractor

Brian now knows about pond liners and he shares what he found with Denise. Together they decide to hire a pond contractor to install their koi pond. They’ll make sure to talk about the liner and get exactly what they want.