Depth of Pool Water

• Before discussing the required barriers, it's important to know which pools require barriers. Under most state laws, pools with more than 18 inches of water require a barrier to prevent drowning. This means that anything larger than a children’s pool must have a permanent barrier surrounding it. According to all state laws, this includes both above-ground and in-ground pools.
  
  

Gates

• The most important and standard access barrier is a gate. Gates in most states must be at least 5 feet high. A pool gate must open outward and have springs that cause it to close on its own. Finally, gates must have a locking mechanism. In fact, some states go so far as to recommend a combination or key lock for a pool gate.
  
  

Door Latches

• A more modern precaution for those with smaller backyards that cannot facilitate a gate is to use a door latch on any doors or gates that have access to the pool. For sliding glass doors in particular, a locking handle must be placed at the top of the door, out of reach of young children. The door must be self closing and more difficult to open than standard sliding glass doors.
  
  

Alarms

• A final precaution required in states such as California is a set of alarms in doors and windows where pool access is possible. The alarms go off every time the door or window is opened, alerting people inside that someone went into the yard.