4. Determining Pond Liner Size

Measuring for Pond Liner

When is comes to pond design, it is important to ensure that your pond liner is the correct size before you begin construction. Without proper measurements, you may not end up with enough overhang. Following the steps below can keep you from having to do this step more than once with your pond design. Remember: measure twice, cut once!

How to determine size:

calculate liner size

Final Length = Length + 2 X Depth(“) + 2 X 12”
Final Width = Width + 2 X Depth(“) + 2 X 12”

1) Find the smallest square or rectangle your pond would fit in from a top view.
2) Draw two cross-sections of your pond. One representing distance A in the diagram the other representing distance B. List all measurements. Example: you would need the distance down to the first ledge, if there is more than one, then the distance across the ledge then the distance down to the next ledge and so on (see example). This would continue until all measurements were filled in on the diagram from one side to the other.
3) On each drawing, add 12 inches to each side for overhang
4) On each drawing, add another 6 inches to each side for a margin of error or any additional material your design calls for.

Firestone is the #1 manufacturer of pond liners in the USA. PONDGUARD is the best liner material available and has a 20-year membrane warranty. In addition, this is the only liner that is tested for toxicity and is “fish safe.” The liner thickness is 45 mil.

Tip! Whenever possible, plan your pond design to use only one liner. Piecing liners together can cause problems with separation and leaking. When joining waterfall liners to the main pond liner, be sure to allow enough length of the waterfall piece to give good overlap.

Don’t underestimate the width of liner required for a waterfall – allow enough extra width to build up dirt and support rock work along the edges to give the waterfall enough depth to contain the water and deliver it to the main pond. 

Protection Mat
5′ wide pond liner underlayment protects against puncture from roots and rocks. Sold per linear foot.

Underlay Felt for Pond Liners 10’x15′ Roll
Underlay Felt for Pond Liners 5’x15′ Roll

Liner Repair Tape
Perfect for seaming and patching holes in liner material. For best results use with a scrubbing pad and Tape Primer. Sold by the foot.
FP8545 3″ Double Sided Zip Splice Tape
FP8543 6″ Cured Repair & Seaming Tape

Black Foam Waterfall Sealant

Savio PUR Black Foam directs water flow over rocks by filling in cracks and voids. It can also be used to secure stone edging and contain gravel on bog shelves. The black color discretely blends with liner and rocks. PUR Black dries faster, lasts longer and is ready to trim in less than an hour.

For waterfall construction, PUR Black is easier and faster than using mortar. Mortar can alter the pH of the water, but PUR Black is inert and will not disrupt water quality.
Dries tack free in 20 minutes, cures in 24 hours.
Fish-safe once dried.

TO101 PUR Black NF Waterfall Foam 27.8oz for Foam Gun

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