Over the many years that I have been installing ponds and
waterfalls, I have seen a lot of "attempts" by so-called professional
pond installers to build a waterfall. About a third of my work is
new pond installations and the two thirds is rebuilding ponds that
other "professionals" have put in. Just because someone knows
how to dig a hole and shows up with crap they bought at Menard's
doesn't mean they know anything about ponds. Know your
installer. I'm not saying you have to go with ME, but ask questions
and look at some of their work. It's your money, after all.
First, let me tell you that rocks do not set on a sloped surface for
very long, especially if that surface is covered with slick, rubber
pond liner. Second, excavated or loose dirt settles. I have seen a
"dirt pile" waterfall settle 2 1/2 feet over the course of a year,
sending the water from the pond in every direction except back
into the pond.
The secret to creating a beautiful waterfall is STEPS. Back in Step
5: Digging Your Pond, I said that you should be able to walk the
entire perimeter of your pond once it's dug. Let me restate: The
entire perimeter of your pond should be level with the proposed
finished water level of the pond. That includes where the
waterfall will enter the pond.
In addition to the reasons I listed above, waterfalls do not work on
a slope because we want the water to flow OVER the rocks and
create a sheeting action. This sheeting action will give you the
sound and look of a real waterfall. We will therefore be cutting
STEPS into the excavated dirt you piled up from the filter box
forward to the pond.
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I use standard 8" x 8" x 16" concrete block when it is necessary to elevate the filter box to the desired finished height, or on
rebuilds, when there is not enough dirt at the job site to build an effective waterfall. For the purpose of this section, all the
pictures shown here are of rebuilds, and therefore the use of concrete block was necessary to achieve the desired results.
Regardless of whether or not you use
concrete block in your waterfall
construction, the principal remains the
same: We are cutting in steps for the
water to flow over. Of course, in the
finished product, the water will flow
over rocks, and not the bare liner, so
you will want to have enough elevation
between your steps to accommodate
whatever size rocks you are using. The
thicker the rock, the bigger the step.
Once the concrete blocks are in place
and filled with dirt (or sand), backfill
against the entire structure.
Make your steps as much like real steps as possible. If they are out of level, or slope down to the next step, you will regret it
when you try to install the rock. Walking up and down the excavated dirt will stomp it in place, but stomp it in place on
purpose anyway. NOTE: The front edge of the filter box should be clear of dirt to at least 4" down to give you enough room to
attach the liner and the imitation rock lip.
When you are satisfied with your steps and the course you have chosen for your waterfall to run, lay down your waterfall
underlayment starting at the flat surface in front of the filter box and working your way down to the edge of the pond. The
underlayment needs to go UNDER the pond liner at the edge of the pond, not on top of it. Next, lay out your waterfall liner,
making sure you have enough at the top to attach it to the filter box straight across with no folds or wrinkles. Run a thick bead
of silicone around the front of your filter box opening and install the imitation rock lip using the screws, washers and nuts
provided. You should end up with one extra of each. Make sure the screws are tight. Otherwise water will seep out the space
between the edge of the filter box opening and the liner, and it will be a tough leak to find!
Once you have the lip of the waterfall installed and all the screws
tightened down, use a utility knife to cut away the liner from the
INSIDE of the waterfall opening.
Working your liner into place from the waterfall lip, down, first,
make SURE you put a fold (about 2" total) of liner directly under
the lip of the waterfall. Even if you are utilizing concrete block in
your construction, the dirt along the front edge of the waterfall
may settle, and if you don't have some extra liner here, the weight
of the rock will pull the liner away from the front of the waterfall
causing it to leak.
As you work your liner into place down the waterfall, set your flat
rocks in place. The flat rocks should be LEVEL. Place them so the
front edge of the rock hangs slightly over the edge of each step.
You should have enough liner on either side (the outside edge) of
the flat rock to lap it over the rock at least 2" - 3".
If you aren't using concrete blocks in your waterfall
construction, just use your shovel to cut the dirt into steps
between the front edge of the filter box and the pond edge.
Take your foam sealant and seal under each flat rock,
lifting the front edge up and running a line of foam all the
way across the step below the rock, then set the rock
back in place. Next, foam seal along the outside edge of
each flat rock. This will cause the water to flow over the
Start with large rocks first, and finish covering the liner
with smaller rocks later once the waterfall is up and
running. Save two of your largest rocks for the pond
edge of the waterfall.
Any sharp turns in your waterfall will cause you to have
extra liner in that area. You will have to fold the liner
there so the water doesn't spill over once the waterfall is
up and running.
The bottom waterfall rock is your most important rock. Not only
will it be the focal point of your waterfall, but if it is not installed
correctly, it will give you years of grief. Before you set this rock,
the liner and underlayment should be placed in THIS order:
1. Pond underlayment first.
2. Waterfall underlayment on top of that.
3. Pond liner on top of the waterfall underlayment.
4. And finally, waterfall liner on top of pond liner.
5. Set your bottom waterfall rock.
It is also extremely important that the POND liner that is under the
WATERFALL liner laps up to the lip of the first waterfall step.
Fire up your pump and see where the water goes. If it doesn't flow over the flat rocks evenly, you can use smaller rocks to
redirect the flow. Now fill in everywhere you see liner with smaller rocks until all the liner is covered and you are satisfied with
The reason for this is because we will be sealing under the bottom and around the outside edges of the bottom waterfall rock
with foam sealant in order to make all the water go over the top of the rock. This will cause the water to "pool" behind the
rock, and if the pond liner doesn't go up high enough at the back, water will seep out over the pond liner that is under and
behind the waterfall liner, and it will be a headache to fix. So make sure your pond liner laps up to the first step up in your
waterfall to prevent seepage.