A Way To Test The Flow Needed For Your Waterfall

The following is a fairly simple and practical way to determine the water flow needed for your stream or pond waterfall. Once you've determined the desired flow, then it's relatively easy to select the right pond or waterfall pump for your particular application.

Place a hose into the stream or waterfall inlet, then screw the other end of the pipe into a water tap in your home. You can then adjust the water flowing through the hose by adjusting the tap.
Then, adjust the water flow using the tap until you are satisfied with the flowing water effect. Experiment to get different effects and flow rates.
Then, without closing the tap, fill a bucket of known volume from the hose. For example, a 5 gallon bucket all the way to the top.
Use a watch with a sweep second hand to measure how long it takes to fill the container all the way to the top.
Now you can calculate the flow rate by dividing the volume of the container by the time it took to fill up.
If one hose does not deliver sufficient water flow, then you can always use 2 hoses to achieve the proper flow.

A rule of thumb for estimating water flow for waterfall use:

For every inch of pond waterfall lip width, allow about 50 gallons per hour of water flow down the waterfall.

When deciding on the height of your garden waterfall, don't make it too high. For most garden ponds or small indoor waterfalls, a waterfall height of about 18" above the water surface is good enough.

Waterfall Pump Selection Table

1. Measure the vertical height of waterfall inlet above water surface of pond (NOT bottom of pond) as measured in feet. This is your pond pump head

2. Measure the width of the water overflow point of your waterfall ... if the overflow is a series of smaller overflows, then add them all together to get width in inches. This is needed to work out waterfall pump flow required.

Check where the height intersects the width in the table below. This is the flow your pump model must deliver.

		Waterfall Vertical Height measured from surface of pond ... (feet)
Width of Water Overflow (inches) See image above		1 ft	2 ft	3 ft	4 ft	5 ft	6 ft
	3"	350 gph	500 gph	500 gph	500 gph	700 gph	700 gph
	6"	700 gph	700 gph	700 gph	700 gph	1200 gph	1200 gph
	9"	1200 gph	1200 gph	1200 gph	1200 gph	1200 gph	1200 gph
	12"	1200 gph	1200 gph	1200 gph	1200 gph	1200 gph	1200 gph
	Example ... you have a waterfall 3 feet above pond surface and overflow is 9 inches wide. You need a pump that will deliver 1200 gph at a height of 3 feet. An example fo such a pump is Danner Supreme Mag Drive 1200 gph as colored yellow above. If you have a waterfall 24 inches wide and 3 feet high you would need 2 model 1200gph pumps TIP: always go for one size larger if in any doubt ... Pumps for small to medium sized ponds and waterfalls

For more on this topic read the pump head and pump pressure articles.

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