The correct reservoir size for a Pondless Waterfall depends on the volume of water in the stream. The reservoir should have enough water storage capacity to hold at least twice the stream's water volume.
How to calculate reservoir size
Calculate stream volume:
Length (ft) × Width (ft) × Average Water Depth (ft) × 7.48 = Stream Volume (US gal)
For a typical stream, use an average water depth of 3 in. (7.6 cm), or 0.25 ft.
Calculate minimum reservoir capacity:
Stream Volume × 2 = Minimum Reservoir Capacity (US gal)
Example
For a stream measuring 20 ft (6.1 m) long × 3 ft (0.91 m) wide × 3 in. (7.6 cm) deep:
- Stream volume: 20 × 3 × 0.25 × 7.48 = 112 US gal (424 L)
- Minimum reservoir capacity: 112 × 2 = 224 US gal (848 L)
The reservoir must provide at least 224 US gal (848 L) of actual water storage capacity.
Important considerations
- AquaBlox: Increases available water storage capacity.
- Rocks and gravel: Reduce the amount of water the reservoir can hold.
- Pump operation: Maintain enough water to keep the pump submerged while operating.
- Reservoir sizing: Use actual water storage capacity, not total excavation volume.