Backyard waterfall overview: Project design
There are a thousand ways
to build a backyard waterfall.
But if you’re looking for
simplicity, you can’t beat
this approach. You basically
dig a hole in the
ground, line it with rubber
membrane and cover it
with a stack of rocks. The
backyard waterfall looks beautiful,
but the best part is the
sound. If you close your
eyes, it’s easy to imagine
yourself sitting next to a
gurgling creek in the middle
of the woods.
Once the materials were
in hand, the waterfall took
less than a day. We were a
little surprised at how
much digging there was,
considering the size of the
reservoir. But this was the
only tough part. Stacking
the stone was fun. We had
to rearrange the stones a
few times, but in the end
the water flowed nicely
over the edges and created
just the effect we wanted.
Step 1: Gather waterfall stones and other supplies
We’ve provided a Materials List in “Additional Information” below so
you’ll know what to shop for. Check local
landscape suppliers and home centers to
find the stone, pump and pond liner. You
can also order a pump online. One source
is discount-pumps.biz. A home center or
lumberyard will have the treated lumber,
rebar, hardware cloth and miscellaneous
hardware you’ll need. We spent about
$150 for 700 lbs. of bluestone and $125 on
the remaining items.
You’ll need a minivan or truck to haul this
much stone, or you’ll have to make several
trips with your car. At the stone yard, start
by finding a large, flat stone for the base.
Ours was about 24 in. across. Then stack
stones on top in an arrangement you like.
When you think you’ve got enough, add a
few more for good measure. Don’t forget to
pick up three or four 5-gallon buckets full
of crushed stone for the base. For this we
used gray stones that ranged from 2 to
2-1/2 inches in diameter.
Backyard waterfall details
Figure A: Backyard Waterfall Details
You can download and enlarge Figure A in “Additional Information” below. You’ll also find a complete Materials List, which you can download.
Buying the Pump
We made the mistake of starting off with
a pump that was too small and were
unhappy with the amount of water flowing.
We recommend a pump with a flow
rate of at least 300 gallons per hour and a
“lift” or “head” of at least 6 ft.
If you don’t have a GFCI outlet within
reach of the pump cord, consider buying a
low-voltage pump instead. It’ll cost a little
more because in addition to the pump
you have to purchase a transformer
(about $35), but that’s a small price to
pay to avoid digging a deep trench.
Buy low-voltage pumps online at
discount-pumps.biz, or ask at the local
landscape supplier. You can mount the
transformer near the outlet and run
low-voltage wire to the pump. Low-voltage
wire only needs to be buried a
few inches. Running new wiring for a
120-volt pump requires an electrical
permit and a much deeper trench.
Step 2: Dig the hole and build the frame
Using 2x8s like we did, you’ll need a hole
that’s about 8 in. deep. In our garden, stone
walls limited the size of our reservoir to
about 30 in. across, but if you have room,
make it bigger. The bigger the reservoir, the
less often you’ll have to fill it with water.
The first step is to cut the 2x8s to length
and nail or screw them together. Use stainless
steel or corrosion-resistant screws. Set
the frame in the hole and level it (Photo 1).
Then spread a 1-in. layer of sand over the
bottom. Cut a square of pond liner about
2 ft. wider and longer than the inside
dimensions of the frame and lay it in place.
Fold the pond liner to fit the inside corners
and let the extra drape down the outside
of the frame. From the leftover material,
cut a 20-in. square of pond liner and lay it
in the center as padding for the two concrete
blocks. Then set the two concrete
blocks into place and wiggle them into the
sand until the tops are level with the edges
of the frame. The blocks will support the
weight of the stones.
Step 3: Assemble the mesh support grid
Next cut pieces of 1/2-in. rebar to span
the reservoir. A hacksaw will work, but it’s
slow going. An angle grinder with a metal-cutting disc is a better option. Attach the
rebar with 1/2-in. copper plumbing straps
(Photo 2). When you’re done, cover the
rebar with galvanized 1/4-in. hardware
cloth. Bend the hardware cloth down
around the outside edges of the box to hold
it in place and hide sharp edges.
Cut an access hole in the hardware cloth
about 8 in. square and between two lengths
of rebar. Once again, fold the edges of the
hardware cloth down to hide sharp edges.
Use this hole to install the pump. Cut another
piece of hardware cloth to set over the hole
so you can cover it with gravel. You’ll use this
access hole to clean out the reservoir occasionally
and to remove the pump in the
winter if you live in a cold climate.
Step 4: Stack the stone
Now for the fun part—building the waterfall.
Spread the stone out near the reservoir
so you can choose the size and shape you
want. Start the stack with your large base
stone. Stack a few stones, then pour some
water over them to see how it flows (Photo
3). You can adjust the position of the stone,
or choose a different one, until you get a
flow pattern you like.
Back to Top
Step 5: Install the pump and watch the water flow
Connect the pump to a length of tubing
with a hose clamp. Allow enough tubing to
reach from the bottom of the reservoir to
the top center of the stone stack. Set the
pump in the reservoir and route the tubing
to the top in the least conspicuous place.
Photo C shows how we held the
tubing in place and directed the water to
the front of the waterfall with duct seal
putty. The duct seal putty also prevents the
tubing from being crushed by the top
Now for the moment of truth. Fill the
reservoir with water and plug in the pump.
It may take a few seconds at first for the
pump to start moving the water. When it
does, see how it flows and make final
adjustments by shimming the stones
Keep an eye on the waterfall for the
first day or two to get a feel for how often
you have to refill the reservoir. On hot,
windy days, it may run low quickly. In
cold climates, remember to bring the
pump inside in the winter so it isn’t damaged
Photo A: Cutting a drip groove using a diamond blade
Photo B: Shimming with small stones
Photo C: Reroute water with dams
Fine Tuning Techniques
If the water isn’t flowing the way you’d
like, here are a few tips to try. You can
cause the water to drip rather than follow
the underside of the stone by cutting a
drip groove (Photo A). If the water isn’t
running in the right direction, shim under
the stone to tilt it and redirect the water
flow (Photo B). You can also create a dam
with duct seal putty (Photo C) to block or
change the water flow.
A. Cut a drip groove for better flow
Create a better waterfall effect by
cutting a groove on the underside of
flat stones. The groove causes the
water to drip rather than flow back
along the underside of the stone.
B. Shim with small stones
Redirect the water by tilting the
stones with small shims. Just lift the
stone and wedge the shim
C. Reroute water with a dam
Make a dam out of duct seal putty to
prevent water from rolling off the
back of the waterfall. Here we also
used the putty to secure the tubing
between the top two stones.