How to Size a Pond Liner

This step by step guide will teach you how to confidently size a pond liner to save you money, hassle and your valuable time. Get it right the first time to prevent any headaches during your pond liner installation.

"HOW DO I SIZE A POND LINER?"

The answer depends on whether the pond has already been dug, or if all you have is a design. First, let's discuss sizing a pond liner on a pond that's already dug out. This is the most accurate way to get a size for the liner. It is also possible to size a liner based on a design only. We'll tackle that in the next section called Sizing a Pond Liner Pre-Excavation.

Sizing a Pond Liner Post-Excavation

Step 1. Determine the longest and widest points

On an excavated pond, which means you already have a hole dug in the ground, you have to take a flat piece of liner and bend it into the 3-dimensional hole. In order to do this, we must add extra length and width to the liner to account for the depth. The liner has to go down the slope, across the bottom and back up the other side. As a result, the liner will be larger than the finished horizontal dimensions of the pond. The first step is to determine the longest and widest point of the pond. To determine the longest and widest points, visualize placing a rectangle on top of the pond so that it covers the pond entirely. Once placed in the most efficient way possible, take note of the longest and widest point.

Step 2. Measure down the slope, across the bottom and back up

Next, take your measuring device and measure EXACTLY where the liner will run at the longest and widest points. Start at the edge of the pond, measure down the slope, across the bottom and then back up to the top. You can measure the distance with a measuring wheel, a measuring tape, a string, or by marking every few feet with spray paint and then adding up the distance from the number of marks.

Step 3. Add extra liner for anchoring

After you have your liner size measured from the edge of the pond, you need to think about how you will anchor the liner. Most people will add an extra 2 to 4 feet around the entire perimeter of the liner. This extra liner can be put into an anchor trench around the outside, or it can simply be laid out over the edge of the pond with landscaping material placed on top. Please see our video on “How to Anchor a Pond Liner” for more details. In addition to adding on extra length and width for anchoring the liner, we also recommend adding 5% extra to account for margin of error. Note: Please be aware that adding an extra 2 feet around the perimeter of the liner will actually increase the liner size by 4 feet. This is because 2 feet needs to be added to both ends.

Ready to order your liner? Visit our liners page!

How to Calculate Liner Size

Sizing a Pond Liner Pre-Excavation

Are you still in the planning stages of your pond build? Are you planning to dig out the pond after you order your liner? If so, you might ask:

"HOW DO I SIZE A LINER BEFORE I START DIGGING?"

As we covered before, this is not the most accurate way to size a liner since measuring is always better than estimating. However, we can still get a fairly accurate estimation if the right steps are followed. We can do this using our Liner Size Calculator.

1. Choose pond style

Does your pond have vertical walls, 45-degree walls with a flat bottom, or maybe gradually sloping walls that meet in the center of the pond? Select the option that best suits your style. If you have a tiered pond with shelves and vertical drops, use the vertical wall option.

Why does the style of pond matter for sizing a liner? The rule of thumb is that the steeper the walls are, the more liner you will use.

2. Enter the max length, width & depth

Step 2 is to input the max length, max-width and max depth of your pond. Sometimes, measuring these dimensions can get confusing if you have an irregular shaped pond. The easiest way to find the max length and width is to visualize placing a rectangle on top of the pond. You can rotate it and move it around until the rectangle completely covers the pond. The max length and width of the pond will be the length and width of this rectangle. Once you have your max length and width, input the dimensions into the calculator to get your estimated liner size. Now you have your liner size! Step 1 to purchasing your pond liner is complete.

Length (ft) Width (ft) Depth (ft)

3. Order liner

Ready to order your liner? Visit our liners page!

Hold on, we aren't done yet. What about your waterfall? How will you like it? See the next section to learn more!

How to Size a Waterfall Pond Liner

Do you have a waterfall? There are two options for lining your waterfall. You can:

A) Extend the main pond liner to cover the waterfall

B) Get a separate liner for the waterfall

The easiest way to line a waterfall is to simply extend the main pond liner to cover the waterfall. However, depending on the size and shape of the pond, this might result in waste. However, if your pond dimensions work for it, using a single liner is likely better since it will ensure that all splashing water is contained. This is the safest way to ensure there is minimal water loss from the waterfall.

Waterfall Liner Length

Step 1. Measure the horizontal distance from the pond to the back of the waterfall

Find the furthest back point of the waterfall. This is usually behind a waterfall filter or spillway. Waterfall spillways, such as the Aquascape Waterfall Spillway actually require you to attach the liner at the back of the unit. Once you have determined the furthest point back, measure the horizontal distance from that point to the pond, record this number.

Step 2. Measure the vertical height of the waterfall

The next step is to record the height of your waterfall off the pond surface. This is the vertical distance from the water to the very top of the waterfall unit. If your waterfall is 3' up from the surface, then record 3.

Step 3. Add on a couple of extra feet

Add the height of the waterfall that you found in step 2 with the length you found in step 1, then add on a couple of extra feet for margin of error and securing the liner to the waterfall. Please see the diagram for clarification.

Waterfall Liner Width

Take the width of your waterfall or stream and add on a few extra feet per side to account for depth and to capture any splashing. When in doubt add extra liner. For example, if you have a 3 foot wide stream or waterfall, add at least 3 feet per side to the liner. So:

3' extra on the side + 3' wide stream + 3' extra on the other side = 9 feet wide.

If you have a particularly splashy waterfall then add on even more liner to the width to ensure all water is contained within the liner.

A waterfall is a common place for water loss due to splashing, so be sure to add enough liner to properly contain the splashing!

At this point, you may be wondering how to attach the waterfall liner to your pond, and that is quite simple!

Attaching the Waterfall Liner to the Main Pond

Simply “shingle” or overlap the waterfall liner, on a vertical drop over the main pond liner. See the image above for details.

Next: Choosing a Pond Liner

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