So, each game consists of 28 minutes of playing time. Each team has timeouts that it can call if in possession of the ball. Substitutions may be made after a goal is scored, between periods, during timeouts, for an ejected player or during running time. For running time substitutions, players swim to their re-entry area and exiting the playing field. The substitute can enter as soon as the head of the exiting player breaks the surface of the water in the re-entry area.
Physical contact is common, as players maneuver for position.
The referee indicates fouls by blowing a whistle and using hand signals to point out the direction of the attack and where the ball is to be put in play. Unlike most sports that stop on a whistle, action in water polo is initiated by the whistle. As in basketball, two clocks are used to time a water polo game. One indicates the time remaining in the quarter. Starting Each period is started with the teams lined up on opposite goal lines.