VGBA and Line Velocities
Pool Design article by Paolo Benedetti, SWD Master
Unless you have been living on a deserted island, you have heard of the Virginia Graeme Baker Act (VGBA). The VGBA applies to ALL swimming pools (residential and commercial) built in the U.S. after December 2008. It also required the retrofitting of all commercial pool drain covers, regardless of when they were built.
The ANSI/APSP-7 Residential Pool Standard used to address safe line velocities. In their “infinite wisdom” the folks on the standards board recently removed the line velocity standards from the ANSI-7 standard. But, you’re not safe to run amuck.
In order for an installed drain cover to remain compliant with VGBA, the line velocity through the cover must remain below 3 FPS. In fact, many of the drain cover manufacturers have specified line velocities of connected inlet pipes in their installation manuals (manuals?? You know, those things that you wipe the mud off of your boots with ?!). Just because a drain cover has XX GPM rating, does not mean you can move XX GPM through the cover exceeding 6 FPS.
VGBA compliant drain covers are also certified in the testing laboratories with “compliant sumps.” For field built sumps the minimum depth is 1.5 times the diameter of the inlet pipe (e.g. 2” pipe X 1.5 = 3” MIN. sump depth). To ensure that your sumps are in compliance, it is best off to use pre-fabricated sumps. This will ensure that you are in compliance and delivering a safe product, while pushing the product liability back onto the manufacturer.
Commercial pools have additional limits placed upon them by ANSI/APSP-1 Public Pool Standard, ANSI/APSP-11 Water Quality Standard, ANSI/APSP-14 International Pool /Spa Code and State & Local Health Departments. In fact, some State Health Codes (e.g. Texas) limit the line velocity at the suction inlets to 1.5 FPS.
The GENESIS® position on line velocities and hydraulics safety can be found at:
GENESIS® members should strive to deliver safe and energy efficient aquatic facilities that exceed the minimum industry standards…. Bigger and slower is always better!
Paolo Benedetti, SWD Master
Aquatic Technology Pool & Spa
PO Box 130
Morgan Hill, CA 95023
T (408) 776-8220