Ordering the Best Pond Liner: What’s a Mil?

While you may have settled on the ideal material for your pond liner, you're not quite finished. Pond liners come in several different thicknesses, and you'll need to weigh long-term durability against ease of installation and price. Once you've settled there, it's time to measure your pond and order the correct amount. As you can see, there's a bit of work still to do!

What are mils?

First, a word about thickness: flexible liners are commonly offered in mils -- a reliable measurement no matter which type of liner you're using. Don't get mils confused with millimeters - although some online "experts" seem to use them interchangeably, they are not related. A mil refers to one thousandth (0.001) of an inch. A 20 mil liner, then, is two hundredths (0.02) of an inch or roughly one-half of a millimeter. Mixing the terms can lead to a lot of confusion, so it's best to make a policy of sticking with mils and asking the person you're speaking with to do the same.

How many mils do I need for my pond?

Most flexible pond liners such as PVC and RPE will start at about 18-20 mils. These thinnest liners are suitable for small, shallow backyard hobby ponds that won't face any particular challenges. Anything thinner than this (even RPE) is unlikely to have the strength or durability to last very long. HDPE liners can be sourced as low as 12 mils, but when combined with the cost of professional installation, it's difficult to imagine how this would be a cost-effective choice.

If a pond is built in a less-than-perfect location, 30 mils is an excellent choice. Small rocks in the soil, nearby tree roots, or a pond that's large enough to require occasional entry for maintenance are all circumstances that will benefit from a sturdier liner. EPDM is available starting at 30 mils, but EPDM always requires underlayment and is still vulnerable to damage during installation. On the other hand, most backyard ponds will last for decades with a 30 mil RPE liner, but if you're planning a swimming pond that will have lots of wear from human activity, for example, it may be worth considering 45 mil RPE. 45 mil RPE is probably a good idea, too, if your soil is very loose.

Keep in mind that these thicker pond liners are heavier, so shipping can get expensive, depending on how large your liner is. Fortunately, using RPE will cut your liner weight in half or better for the same thickness, and you may even be able to use a thinner product to get the same protection compared to any of the competitors.

If you're still not sure which option will suit your needs, contact us or give us a call at (541) 447-0712. Our expert team can quickly help you assess your situation and make specific recommendations.


Liners by BTL

AquaArmor Pond Liner

The most versatile liner on the market today, AquaArmor maximizes protection from harmful UV rays, tear resistance and punctures that cause leaks. Simply the best liner on the market.

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