Virginia Graeme Baker Pool and Spa Safety Act - Pub. L. 110-140
Sec. 1403. Definitions.
(7) UNBLOCKABLE DRAIN.-
The term `unblockable drain' means a drain of any size and shape that a human body cannot sufficiently block to create a suction entrapment hazard.
ANSI/APSP/ICC-7, 2013
Gravity flow systems are systems that incorporate a receptacle or container as part of a circulation system that is vented to atmosphere and receives water from the pool/spa or water feature by force of gravity, from which the pump draws its water supply. [from definition of vented reservoir]
vented reservoir: A receptacle or container incorporated as part of a circulation system that is vented to atmosphere and receives water from the pool/spa or water feature by force of gravity, from which the pump draws its water supply. Systems including vented reservoirs are commonly referred to as , , or . Vented reservoirs include but are not limited to the following: catch pools, surge tanks, collector tanks, skimmers open to the atmosphere, atmospheric vent, gutters, overflow gutters, or perimeter gutter systems.
N.H. Admin. Code Env, Env-Wq, ch. Env-Wq 1100, pt. Env-Wq 1116, app D