The Virginia Graeme Baker Act permits single main drains in commercial swimming pools and spas. However, our opinion is that the safest solution for preventing evisceration and entrapment of pool patrons is properly sized and installed multiple main drains or unblockable drains, and that single main drain configurations continue to present risk. The following is an overview of the risks and recommendations.    

Evisceration and Entrapment in Swimming Pool and Spas

Evisceration (disembowelment) and Entrapment have resulted in severe injuries and deaths in swimming pools. Evisceration is the removal of some or all of the organs of the gastrointestinal tract (the bowels). For this discussion we will use the term evisceration, referring to the bowels being completely or partially suctioned out of a person by a swimming pool or spa main drain. Entrapment in swimming pools is the trapping of a body to the main drain due to the suction of the main drain, thus holding the body underwater against the persons will, often resulting in drowning. 

It is important to note that the Virginia Graeme Baker (VGB) Pool and Spa Safety Act required all non-residential pools to install newly designed drain covers and to have 1.) multiple (at least two) main drains, or 2.) a single main drain with a device designed to prevent entrapment (secondary anti-entrapment system) such as a Safety Vacuum Release System (SVRS), automatic pump shut-off system, or suction-limiting vent system.  The VGB Act is aimed at preventing entrapment, which has resulted in drowning.  But the current law still leaves open the possibility of more tragedies, as we discuss below. 

Scenario 1.) Multiple Main Drains
A pool with multiple (at least two) main drains, sized and installed according industry standards and drain covers securely in place, is a very safe situation. As a matter of fact, we have not been able to find evidence of even one injury due to main drain suction in a pool with properly installed multiple main drains and main drain covers in place, even before the newly designed VGB compliant covers were required. The only maintenance required is to replace the drain covers every 7 years or so, as stamped on the cover.

Scenario 2.) Single Main Drains
Prior to the Virginia Graeme Baker Pool and Spa Safety Act there were locations in the United States where pools with single main drains, with no secondary anti-entrapment device, were allowed to operate. These pools were dangerous to the pool users, especially wading pools, spas and other shallow pools. Today, it is illegal for a commercial swimming pool or spa to operate with a single main drain and no secondary anti-entrapment device, unless the drain (including the sump) is so large that it qualifies as “Unblockable”, or the drain is conneted to a “Gravity Drainage System”.

Our concern is with pools with single main drains and secondary anti-entrapment devices.

First and foremost, if a secondary anti-entrapment device is not operating properly, then the result is the same as a pool with a single main drain with no secondary anti-entrapment device: A dangerous single main drain pool. Since these are mechanical devices, the likelihood exists that they will fail at some point. Most manufacturers recommend testing the devices once a month while the pool is open to swimmers. However, a device could break and need repair before it is tested again, in which case a pool may be unknowingly operating with a single main drain with no secondary anti-entrapment device until the next test. Note that if a test shows that the secondary anti-entrapment device is not working properly, the pool must be immediately closed and remain closed until the device is repaired or replaced.


Regarding evisceration, evidence suggests that with a single main drain there may be no way to protect against evisceration, because evisceration can occur in time as short as 0.25 to 1.86 seconds, depending on factors including the victim’s size, age and gender.1   In research conducted by The Pool Safety Council, Florida Tech professor Steven M. Jachec, Ph.D., P.E. performed an analysis to determine how quickly an SVRS can react. His trials showed times from 0.50 seconds to 4.0 seconds in eight trails.3  - longer than the time for injury from evisceration to occur. So, even with a perfectly working SVRS, injury from evisceration may occur in a single main drain pool or spa.

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In closing, while the VGB Act maintains single main drain pools as legal, we support converting all pools to multiple main drains to best decrease the risk of evisceration and entrapment in swimming pools and spas.


1 The Pool Safety Council
2 APSP INDUSTRY NEWS, Pool Safety Council Studies Raise Entrapment Questions, Rebecca Robledo, 10.7.2010
3 PSC pdf

The Pool Management Group evaluates research and information related to swimming pool patron safety to share with pool patrons and pool owners. We respectfully offer our opinion, based on our experience and knowledge in operating 750 commercial pools annually.