Pump Sizing for Overflowing Fountains

A great rule of thumb for pump sizing for overflowing fountains:

Allow 10 - 20 GPH for active edge (edge where water is actively overflowing) for bubbling rocks, overflowing vases and basins.

Formula:  10 - 20 GPH X 3.14 x diameter (in inches)  


  • 400-800 gph for 12" fountain diameter
  • 600-1200 gph for 18" diameter
  • 800-1600 for 24" diameter
  • 1200-2400 for 36" diameter

*Rougher surfaces require greater flows but may splash more

 Use the calculator below by entering your fountain diameter.  Based on the flow rates calculated below, find a pump that has your desired flow rate at the head height needed.



  • Typical splash zones extend from the source as far out as the feature is tall. A feature 3' tall may splash out 3' in every direction, a 6' diameter splash zone.
  • For in-ground installations taller than 23” on an FB4600, or to capture splash from tall drops or excessively rough surfaces, consider creating a liner ‘skirt’ around the basin or reservoir.
  • If splash is caused by water impacting the surface of the basin or reservoir, place a Splash Mat on the horizontal surface where water is falling to capture and suppress any splash. Splash Mat CFSPMA2820 may be purchased in rolls of 28"W x 20'L.
  • With all Fountain Systems, the use of an Automatic Fill Valve AF1000 to compensate for splash and evaporation losses is strongly recommended. 

Source: Atlantic-Oase