Building Liner Ponds
by Brett Fogle
Reprinted, with permission, from Pond Stuff, newsletter of
of Baton Rouge, Florida
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
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
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
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
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
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
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...
Brett Fogle is the owner of MacArthur Water Gardens and several
pond-related websites including macarthurwatergardens.com and pond-filters-online.com.
He also publishes a free monthly newsletter called PondStuff! with a reader circulation of
over 6,000 pond owners. To sign up for the free newsletter and receive a complimentary
'New Pond Owners Guide' for joining, just visit http://www.macarthurwatergardens.com
Specializing in pond filtration and clear water solutions since 1995