Pond Doc's Pond Construction Education Center - Figure the Liner Size of the Pond You Are Building

Figure the Exact Size of the Pond for Purchasing the Liner

Waste Not, Want Not!
If you are planning to use a liner in your pond - please pay close attention. It will save you a lot of headaches later on. One of the most important things to consider when determining the exact size of your pond is knowing in what sizes the liner is available. You normally can get liner cut to the length you need but it only comes in a few widths. The normal widths that 45 mil EPDM rubber liner (the kind of liner that we recommend) is available are 5.5 ft. (for waterfalls or streams), 10 ft. (for wider waterfalls and streams or small water features), 15 ft., 20 ft., 25 ft., 30 ft. and 35 ft. It is often hard to find 35 ft. widths but they are available. Anything larger must be custom ordered and can take a long time to come in.

The reason you need to know what widths are available is that you certainly should not waste any money on liner you don't need. It is charged by the square foot. Let's say that the size liner you will need for your pond is 27' x 26'. You would be forced to buy a 30' x 26' piece. That's 780 square ft. The piece you need should only be 702 square feet. Now, let's say the price is .75 per sq. ft. You would waste 78 square feet of liner which would equate to $58.50 you didn't need to spend. I would bring one of the dimensions in to make it 25 ft. That means you would order a 27' x 25' piece of liner which is only 675 square feet and has no waste. You can easily see why it's better to figure this now during the designing step of your project and not after the hole is dug!

Here's how to decide the exact size of your pond-to-be. Make yourself a diagram of the cross section of your pond like the one I've made for our learning project. It should be representative of the widest section of the pond. For the sake of getting the most out of the liner you simply CANNOT say that your pond is 22 feet wide. You must consider that the liner will need to go up and down and over all the shelves then you will need 1 1/2 feet on each side as overlap. You do not want to short-sheet yourself on the liner!

The three measurements that are most important for sizing the liner are the width of the pond, the depth of the pond and the overlap.

Our Project Pond

The above illustration is a cross section of the widest LENGTH of our project pond. It is 22 ft. wide and 4 ft. deep (including depth of the rock shelves). To get the width of the liner I need I would add the total width of the pond (22 ft.) plus the depth (4 ft.) x 2 for each side = 8 ft. plus the overlap of 1 1/2' on each side = 3 ft. So - 22 ft. + 8 ft. + 3 ft. = 33 feet total. I can get a liner cut to 33 ft. in length but I need a width of no more than 30 feet when I figure the maximum WIDTH of my pond or I will be forced to purchase a 35 foot width which is hard to find and there would be a waste factor. So I'm going to limit the size of the WIDTH of my pond to 19 feet so I can purchase a 30x33 foot piece of liner.

I have officially determined the size of our project pond...

The WIDEST part of our project pond is 19 feet and the longest part is 22 feet. The total depth is 4 feet. The liner I need is a 30x33 piece. But wait! What about the waterfall? It MUST have liner under it as well. There are two things we can do. We can increase the length of our liner piece or order a separate piece just for the waterfall. Since our project pond's waterfall is only about half the size of the width of the pond we don't want to waste that much liner so we'll order a separate piece. Lining waterfalls can be tricky. You almost have to have the waterfall built up before you can get a true measurement. We can get liner rather easily and quickly so we'll wait until we get the waterfall built up before we actually size the liner for it.

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