“How to Build a Pond” is a vague statement. We are going to answer this question with two brief explanations: how to install a preformed pond and how to build a pond using a pond liner.



Installing a Preformed Pond



Installing a preformed pond can typically be done in an afternoon and within a few steps:



  • Put the Garden Pond on the selected site and use a shovel to mark its shape. This can easily be done by turning the pond upside down and tracing the outline with a shovel, or, laying a garden hose around the garden pond perimeter to mark the shape.

  • Excavate a hole 2” deeper than the pond to allow for a protective layer of sand.

  • Install and level your new garden pond. Add a little bit of water into the garden pond to stabilize it so it stays “within bubble” on the level.

  • Start to fill the pond while taking care that it stays level. Use dirt and sand to fill in any gaps around the sides.

Now you are ready to install a pond filter kit, or a water fountain, or waterfall or other water feature in your backyard pond. Check our pages on water quality and fish health before stocking your pond with Koi or other pond fish.

Preformed ponds are fairly simple to install. Digging a hole to fit the preformed pond can be next to impossible so it’s a good idea to over size the hole, insert the pond, and back-fill the hole around the inserted preformed pond.



There are many different filtering options for preformed ponds with regards to filter systems, water features, spitters, and fountains. There are submersible filters as well as pump and filter kits that often come with accessories like fountain heads. There are also “all-in-one” filter systems that have integrated UV clarifiers that are excellent for preformed ponds and even smaller ponds constructed from pond liner.



How to Build with Pond Liner


How to Select a Site for a Koi Pond, Water Garden, and Fish Pond

When building a pond, it’s important to locate the pond in an area that gets sunlight, does not collect water, and can be installed where runoff will not enter the pond.


How to Dig a Pond

Excavation of a pond equates to the foundation of a home or building. Ponds with bad excavations have problems down the road resulting in leaks and maintenance nightmares. Spending the time digging out the pond properly will help with a low maintenance pond.


When excavating the pond, we recommend excavating ledges for stone and/or pond plants. Excavating a pond in this manner allows for a natural looking finished koi pond where EPDM pond liner will not be seen once the project is complete. Dirt from the pond excavation can be used to level up the pond perimeter and it can be piled up for a waterfall.


The entire bottom of the pond should be sloped slightly towards the pond skimmer, or sloped towards the side of the pond where the pond pump or bottom drain will be located. This helps debris settle towards one side of the pond for easy removal, or, end up in the pond bottom drain where it can be pulled into the pond skimmer and then the pond filter system where it belongs.


How to Install a Pond Liner; How to Install an Underliner


To calculate what size EPDM pond liner is needed and the underliner needed, use our pond calculators, or the following formula:

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

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

Keep in mind, EPDM pond liner comes in widths and lengths divisible by 5. For example, 15 x 25 or 10 x 30, etc. Pond underliner comes in a wide variety of widths and lengths. Since underliner does not have to hold water, it does not have to be a single piece.

Pond liners are tasked with holding a lot of water and thousands of pounds of rock, stone, and gravel. Installing a pond underliner, or installing a pond underlayment increases the puncture resistance of EPDM pond liner by over 300%. Although EPDM pond liners are the liners of choice, especially 45mil EPDM pond liners, they are not completely indestructible.



EPDM pond liners should be installed so there is at least 1 1/2′ overhang all the way around the pond. This may seem excessive, but, remember that 3-5 years down the road the area around the pond, and areas within the pond, will settle and the extra pond liner will be needed to pull back up over the side.

PB07 Kicking Liner

When installing a pond liner. It is imperative that the pond liner, all of the pond liner in the pond, is laying on the ground and there are no air pockets or the liner is not stretched with an open void underneath the it. These two situations can weaken pond liner. Do not be afraid to get into the pond and walk over the liner to make sure the pond liner is placed into all the nooks and crannies of the pond.

The next step is to begin connecting the pond liner to any components that will be used, like a pond skimmer, a waterfall spillway for a waterfall filter, and/or a bottom drain.




Once the components that need to be connected to the pond liner are connected to the pond liner, the rock and stone can be installed into the pond and waterfall.

Installing stone and rock into a waterfall is an art and a science :). It’s kind of like putting a puzzle together without a picture for reference. We typically recommend rounded shaped stone for the pond perimeter and ledge stone for waterfalls. To finish everything off, a decorative gravel or creek gravel can be used to fill voids and give the pond a natural appearance.




In the event larger stones are being placed on the pond liner, it is a wise idea to place some pond underliner or rock mat on top of the pond liner so the rock does not puncture the pond liner. In some applications, such as the pond below, it may be wise to install a 60mil EPDM pond liner versus a 45mil EPDM pond liner.




At some point in time, the pond tubing or pond hose is installed from the pond pump to the pond filter. There are a a couple different types of pond hose or pond tubing that can be used in most installations. Kink free tubing is very popular and great for most do-it-yourself types of pond equipment. Flexible PVC is typically used by most professionals and comes with most pond kits on the market. Kink free tubing is very easy to install and clamps onto fittings that come with pond pumps and pond filters. Flexible PVC is typically sold with larger pumps and is made to glue into fittings. Flexible PVC is typically used with pond skimmers, check valve assemblies, and waterfall filters. Most pressurized pond filters are not accommodated to handle flexible PVC.


Flexible PVC for ponds is very durable and can tolerate freezing conditions. The only real drawback to flexible pond pvc is that the term “flexible” is relative. It is more flexible than rigid PVC, but, it does not have the ability to make abrupt 90 degree turns like kink free pond hose.


Determine the size of the pond pump and pond filter needed for your new garden pond using our formulas page and the pond calculator on the left of this page. Treat the water to eliminate chlorine/chloramines and adjust the pH to acceptable levels before adding pond plants and pond fish. Add beneficial bacteria to jump-start the pond filter.


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