Building Liner Ponds

Surprisingly enough, it is usually in mid-summer that many

gardeners begin to think about installing a small pond or

water garden. Ponds don’t need to be weeded or watered, and

they can supply exuberant color in the form of water lilies

and bog plants.

The sound of a splashing fountain or waterfall is more

appealing than weeding a flower bed or mowing that section of

lawn. Best of all, no matter how hot or wet it gets, the pond

just keeps on blooming!

At this point you may start to think about the expense and

labor of installing a concrete pond, and our 95 degree days

are just about enough to stop this pond daydream in its

tracks.

However, with the advent of newer pond liners and pre-formed

pools, the misery associated with concrete mixing and

finishing is a thing of the past. Heavy duty pool liners with

10 year guarantees are now common, and can sell for as little

as $1.00 a square foot.

Preformed ponds in many different shapes and sizes are also an

alternative method to create a quick pond at less cost than

using concrete. Using these materials, the average gardener

can install a decent size pond in less than one day, and have

it stocked with plants, fish and fountain by the following

morning.

The simplest kind of pond to build is an above-the-ground

pond. Since no digging is required, it usually takes much

longer to fill this pond with water than it does to build it!

There are many variations on this theme, but as an example,

one can use treated lumber planks which are at least 2 inches

thick by 12 inches wide, nail them together to form a

rectangular shape of the desired dimensions, and place the

form where the pond is desired.

This bottomless “box” can be placed directly on the grass,

concrete, a deck, etc., and then the bottom is covered with

some kind of padding or cushioning material. Most books say to

use sand, but I think the perfect material is roofing felt. It

is cheap, convenient, lies flat, makes a barrier to weeds, and

provides a good cushion for the pool liner.

Once the roofing felt is in place, the pool liner can be

dropped into the form and you begin filling the pond with

water. A few staples on the outside of the pond form may be

needed to keep the liner from blowing into the pond, but be

sure to use just a few, and place them at the edge of the

liner.

As the pond fills, the weight of the water will do a good job

in smoothing out wrinkles, but if you are a perfectionist, you

can help smooth them out by hand before there is more than one

inch of water in the bottom of the pond. While the pond is

beginning to fill, you can check the level of the form, and if

it needs to be raised a little on one or two sides, this can

be done by carefully inserting some shims to raise the forms

where needed.

If you prefer the pond to overflow on a certain side (like,

into the flower bed, rather than onto the deck!) then you may

want to leave the overflow side a quarter inch lower than the

rest of the pond.

You should wait until the pond is completely filled before

cutting any excess liner or doing any permanent stapling. This

will give the water pressure enough time to pull the liner

into every nook and cranny where it needs to go; some of those

few holding staples which you used to hold the liner in place

may actually tear loose as the pond fills, but if you stapled

the liner on the outside of the form, near the edges, then no

harm is done… you will be trimming some of that excess liner

off, anyway.

It really does take longer to fill this kind of pond than it

does to build it. I once built a twenty-by-thirty foot pond in

two hours but it took all night for it to fill with water.

I think an ideal depth for an above ground pond is about 14

inches, but it can be deeper or more shallow than that,

depending on what materials you are using for the form.

Railroad ties, landscape timbers, concrete blocks, etc. are

all possible materials for pond building.

Remember that any kind of wood must be pressure treated if you

want it to last more than a year! Although I mentioned

rectangular shape, if you have some carpentry skills, you can

also do triangles, pentagons, ponds within ponds, etc.

Ponds built with treated lumber planks do not need any side

support if they are less than 8 feet or 10 feet long; if you

are building larger than that, you will want to drive a stake

into the ground where the planks are to be nailed together, so

the water pressure won’t make the planks bow outward. So, if

you know how to use twelve nails to nail four planks together,

then you can build a pond. If you are feeling lazy, have the

lumber yard cut the planks to size you need. Borrow your

neighbor’s staple gun, find those scissors buried in the

kitchen drawer, and you are in business!

Pond liners can also be used to make an in the ground pond.

The advantage is that you can make any shape pond you want,

and the ground itself supports the sides of the liner.

It is a good idea to use a flexible garden hose to lay out the

pool shape you want. Once everyone agrees that it is a

pleasant shape, and it is large enough, you can dig a trench

along side the hose, and start digging.

Remember, the pool does not have to be more than 12 to 16

inches deep, so don’t get carried away. If you want a

waterfall, some of the excavated soil can be mounded up near

the pond for later waterfall construction. In some cases, it

may be useful to use some of the soil for a berm around the

pond, so that is another way to dispose of excavated soil.

Once the pond is excavated, check the level, decide which side

you want excess rainfall to flow from, and then you are ready

to line the hole with roofing felt, running it across the

pond, up the sides onto the edges of the pond. Drop the liner

in, weigh it down lightly with some rocks around the edges,

and start filling.

Again, do not trim any excess liner until the pond is

completely filled. Some pond books say you should create a

shallow shelf in the pond before putting in the liner, but

they don’t have our river sand and rainfall to deal with. I

think it is better to build the pond to a depth of 14-16

inches, and just use bricks to prop up those bog plants that

don’t want to sit too deep in water. This gives greater

flexibility in rearranging the pond plants as you wish, and

avoids the calamity of a shelf suddenly slumping into the

pool. When using pool liners, whether in the ground or above

the ground, it is important to conceal the edges from

sunlight, since that is what eventually breaks down most

liners.

Using stones or lumber planks to finish off the edge of your

pond will make it more appealing, and enable the liner to live

up to its ten year guarantee. Even the heavier, preformed

plastic ponds should have their edges covered by sod or some

paving material, so the sun can’t reach it. Some final

pointers: if possible, locate your pond away from trees, in a

place that gets at least five hours of direct sun daily. This

will allow you to grow a wide variety of pond plants.

Be sure to use a dechlorinating product when you first fill

the ponds… the new chemicals in our drinking water do not

dissipate quickly and they will kill your fish and damage your

plants, even ten days after you have filled the pond!

Be sure you are pleased with the size and shape of your pond

before you start – so you won’t say “I should have made it

bigger, or longer, or rounder, etc.”, within two hours of

filling it!

Rule number one in pond building is that no matter how big

your pond is, you always want a bigger one.

Last, but not least, if you decide to do an in-the-ground

pond, why not serve refreshments and get some friends to help

. . . friends will have all kinds of useful ideas on how you

should do it … which is fine, as long as they keep

digging…