Building Our Waterfall Part 3: Sizing The Waterfall

With the catch basin correctly sized, 

the next step is more interesting: 
determining the flow of water 

over the waterfall.

The components of a disappearing waterfall include the waterfall catch basin as the source of the water, a submerged pump in the catch basin that circulates water through tubing up to the head of the waterfall where it empties into a weir (this is just a box which diffuses the water to create a natural appearing waterfall) before spilling over the lip of the weir and cascading down to the rocks below. Gravity then encourages the water down the stream-bed if you have one, where it collects in the catch basin, ready for the return trip up the tubing.

In order to size the pump, 
you need to decide how much water you want to flow over a waterfall. 

Half-inch deep waterfalls are common for residential water features, which really is plenty to give you a sound that you will enjoy. The Waterfall Flow Calculator will reveal that wider waterfalls and deeper flows come with a cost—the need for a bigger pump. Note that the resulting recommendation of the calculator (in gallons per hour, or gph) is how much flow you need at the top of the waterfall. 

Calculating the Pump Size

If the recommended flow at the top of the waterfall is 1,200gph, you will need a pump rated at more than 1,200gph, since you will need to factor in the amount of force needed to push the water to the top of the waterfall. This force (also known as head pressure) is influenced by the height of the waterfall, the length of the tubing you are using, and the fittings used to connect the tubing. Pumps are rated at being able to deliver a quantity of gallons per hour depending on the head height, which really means the calculated head pressure—not simply the height of the waterfall. This Head Pressure Calculator will tell you the height of your waterfall as perceived by the pump.

For example, if your waterfall is 3 feet high, and you have one 90 degree fitting, 15 feet of pipe, and two other fittings, this would be equivalent of lifting the water 8.5 feet high. When shopping for pumps, you will need to find one that delivers 1,200gph at 9 feet head height, not 3 feet.

Once we knew the correct head pressure for our waterfall,

we could then select the right pump.

After researching our choices, 

we purchased a 1200gph Atlantic TidalWave2 hybrid pump 

from our local sprinkler supply store that proved very capable.

♦  ♦  ♦

The waterfall and stream begin at the waterfall weir. 

Here’s a good picture of a weir. 

As you can see, they can be expensive. 

Next post I’ll show you how to build one for much less.

Building Our Waterfall Part Two: The Catch Basin

Water features can be designed to fit almost anywhere in the home garden. 

We determined early on that we would forgo the pond of standing water, 

opting simply for a disappearing waterfall. 

Previous experience with a pond convinced us that pond upkeep was more than we cared for, and besides, it was the sound of falling water that we were seeking.

Eastward view of the Stream

There are a myriad of design choices for a disappearing waterfall.
We had enough space in our garden corner to install 

both a waterfall and a short stream, 

but you can omit the stream if your space is limited 

and just build the waterfall right on top of the catch basin. 

The end of the Stream... where does the water go?

Once you've determined where you want the head of your waterfall, 

and where you can locate a sunken waterfall basin, 

your next step is to calculate 

how much water your waterfall catch basin will need to hold.  

For assistance here, we visited a very helpful website.  The waterfall basin calculator takes into account the projected length, width and water depth of the waterfall and of the stream, and calculates the volume of the waterfall basin in gallons. You will need a basin that can hold all of the water in your system when you turn off the pump as all the water will flow down into this basin. This site does the calculations for you to determine the size of your catch basin.

Once you have determined the size of the basin, you could, of course, purchase a waterfall  kit that includes the basin, but we found the kits to be rather pricey and as we are always on the lookout to complete a project with the least amount of money, we went on a hunt to find just the right basin. 

We found a very suitable and sturdy basin at the local farm supply store for a fraction of the cost—a 40 gallon Rubbermaid horse watering trough. This was just the right size and shape for our waterfall.

Be sure your basin is level

 Now we could place the trough in the desired location... 

at the end of where our stream would be.

Can you see the path where our stream will lay?

Monday's post will include information 

on how to select the right pump for your waterfall.

This is a series of posts on how we built our waterfall.

If you've missed any, view the  previous posts below...

Building Our Waterfall Part One: Preparing the Foundation

 Anything I can dream... my Honeyman can build.
 

And this is what he built for me... (and he let me help.)

We have a beautiful Patio (read our story here) built in 2009,

that we especially enjoy on warm Summer nights.

  The adjacent landscape is striking...
 but something was missing.

 My heart yearned to hear the refreshing sound of water splashing

in my gardens 
at the end of a Summer's day.
(Anything I can dream?)

And so we began... 

It was April of 2011 
and our sleepy gardens were just beginning to awake.

Remember this is Utah 
where all but the bones of the gardens 
die back and all but disappear from the cold Winter months. 
 (One of the reasons I love the month of April ... watching as the barren landscape SPRINGS to life.)

We had dug out the bushes from the existing landscape in the Fall, 
so we began by transplanting the emerging plants, 
rerouting the sprinkler pipes 
and scraping the garden soil down to the clay base...
but only where the waterfall and stream would be.
After all... this was my perennial garden and I didn't
want to disturb the emerging plants and slumbering seeds.

 We stock-piled the scraped off garden soil 
to later place around the waterfall and stream at project's end.

The head of the waterfall would be up near the house, 
so we prepared a gentle slope down to the rocks already in place 
that lined the perennial bed. 

These were the river rocks that were gathered from our soil 
when we first landscaped our property,
and we planned to incorporate them into the design of our stream.

The foundation of the waterfall head 

was laid in place with cinder blocks.

We packed our clay soil firmly in and around the blocks 
to provide a solid base for the waterfall.

We'll further build this up with large river rock... 
but wait, I'm getting ahead of myself, 
that will be another day's post.

Surely growing weary of hearing my repeated cautions  
to not step on my precious emerging peonies, 

my Honeyman covered several of them with pots 
to assure their safety in the construction zone. 

What a guy. 
Would contractors ever step so lightly?

♦  ♦  ♦ 

Our next post will include the engineering side of our project.

Did you know that the height of the waterfall

and the length and width of the stream are all determining factors 

of how large the holding basin must be at the base of the stream?

Then there is the issue of the pump...

what size is right for your project?

The answers to these questions will be discussed in our next post.

Stay tuned!