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20 Mil LLDPE Pond Liner

20 mil LLDPE Pond Liner (Linear Low-Density Polyethylene)

  • Economical liner with excellent durability, high impact strength and puncture resistance. Pliable and flexible; conforms to a variety of irregular surfaces
  • Excellent choice for projects like water gardens, fish ponds and backyard waterfalls. Attaches easily to waterfalls and skimmers; fits into corners and follows contours along the sides and bottom of your pond
  • Resists stress cracking and UV deterioration. Completely safe for fish, wildlife and plants. Standard 10-year warranty when exposed to direct UV radiation; lasts indefinitely when covered by earth, rock or water
  • Standard 10-year warranty when exposed to direct UV radiation; 40 plus year non-exposed life expectancy when covered by earth, rock or water.
Add underlayment to your liner to add extra stability and puncture resistance to your feature

If you have questions about LLDPE Pond Liner, please visit the FAQ


We have paired the closest size Geotextile Underliner we make to go with your LLDPE Liner. Simply select size from the chart to purchase your liner and add geo to it in the shopping cart!
6 x 5 12 x 10 18 x 15 25 x 15 37.5 x 20 50 x 30 62 x 30
6 x 10 12 x 15 18 x 20 25 x 20 37.5 x 30 50 x 45 62 x 40
6 x 15 12 x 20 18 x 30 25 x 25 37.5 x 35 50 x 50 62 x 45
6 x 20 12 x 25 18 x 35 25 x 30 37.5 x 40 50 x 70 62 x 50
6 x 25 12 x 30 18 x 40 25 x 35 37.5 x 45 50 x 80 62 x 60
6 x 30 12 x 35 18 x 45 25 x 40 37.5 x 50 50 x 90 62 x 70
6 x 35 12 x 40 18 x 50 25 x 45 37.5 x 75 50 x 100 62 x 80
6 x 40 12 x 45 18 x 75 25 x 50 37.5 x 100 50 x 200 62 x 90
6 x 45 12 x 50 18 x 100 25 x 75 37.5 x 200
62 x 100
6 x 60 12 x 75 25 x 100 62 x 200
6 x 100 12 x 100








Frequently Asked Questions

1. What is LLDPE?
Linear low-density polyethylene (LLDPE) is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins. Linear low-density polyethylene differs structurally from conventional low-density polyethylene (LDPE) because of the absence of long chain branching.

The linearity of LLDPE results from the different manufacturing processes of LLDPE and LDPE. In general, LLDPE is produced at lower temperatures and pressures by copolymerization of ethylene and such higher alpha-olefins as butene, hexene, or octene. The copolymerization process produces an LLDPE polymer that has a narrower molecular weight distribution than conventional LDPE and in combination with the linear structure, significantly different rheological properties.
2. What size liner do I need?

The formula for sizing a pond liner is:

(Pond Length') + (2 x Pond Depth') + (2') = Liner Length'

(Pond Width') + (2 x Pond Depth') + (2') = Liner Width'

So... if you want a finished pond that is 12' long, 7' wide, and 3' deep; then using the formula above, the liner size you need is:

(12') + (2 x 3') + (2') = 20' Long

(7') + (2 x 3') + (2') = 15' Wide

This basic formula will work for ALL pond shapes.

3. How many gallons of water is in my pond?

The formula for determining the number of gallons of water in a pond is simple.

(Pond Length') + (2 x Pond Depth') + (2') = Liner Length'

For Square and Rectangular Ponds:

(Pond Length') x (Pond Width') x (Pond Depth') x 7.5 = Gallon Size

For example, if you want a finished pond that is rectangular in shape, and is 12' long, 7' wide, and 3' deep; then using the formula above, the gallon size of your pond is:

(12') x (7') x (3') x 7.485 = 1,890 Gallons

For Oval Ponds:

(Radius1') x (Radius2') x Pi(3.14) x (Average Depth') x (7.485) = Gallon Size

For example, if you want a finished pond that is oval in shape, and is 12' at the widest length accross, 7' at the shortist length accross, with a 3' average depth; then using the formula above, the gallon size of your pond is:

(6') x (3.5') x (3.14) x (3') x 7.485 = 1,480 Gallons

4. How deep should I make my water feature?

For fish ponds, a depth of at least 18", or deeper is recommended. Healthy fish LOVE to move up and down, as well as side to side!

For water gardens, the water feature should have a depth of at least 12", or deeper.

Check your local fence requirements (building codes) and freeze line depth.