Each game and period in Olympic water polo starts with a swim-off, which is a race for the ball in the center of the pool. Players from each team are lined up along their own goal lines and the first team to reach the ball has the first possession of the game. After each goal, the game is resumed by the team who conceded. 

A side has a maximum of 30 seconds to possess the ball before attempting a shot at the opponent’s goal. If the team with possession has not taken a shot before the 30 seconds is up, an ordinary foul is rewarded to the other team. 

There are four types of fouls in Olympic water polo: exclusion fouls, ordinary fouls, penalty foul and personal fouls. 

Exclusion fouls are a variety of offenses that are punished by awarding a free throw to the opposing team, with the addition of the player who committed the foul being excluded from gameplay for 20 seconds or until a goal is scored or until the player's own team regains possession. Examples of these fouls include: interfering with a free throw, intentionally splashing water in an opponent's face, kicking or striking an opponent, using foul language, showing disrespect for a referee or other official and committing an act of brutality. These fouls are sometimes called "major fouls." Players who receive an exclusion foul head to the designated exclusion area outside the field of play and wait to return to the game after their punishment is over.

Ordinary fouls are a variety of offenses that are punished by the opposing team earning a free throw from the point of the foul. If a defending player commits an ordinary foul within the 2-meter area, the free throw is taken from the 2-meter line. Examples of these fouls include: holding onto the goal posts, holding the entire ball underwater, hitting the ball with a clenched fist (the goalkeeper is allowed to do this within five meters of the goal), touching the ball with both hands at the same time (the goalkeeper is allowed to do this), impeding the free movement of an opponent who is not holding the ball, pushing an opponent and wasting time. These fouls are sometimes called "common fouls" and are responsible for approximately 90% of all whistle activity from the referees. 

Penalty fouls are a variety of fouls that are punished by the opposing team being awarded a penalty throw from behind the 5-meter line. Any member of the team that's awarded the penalty throw may take the shot. Examples of these fouls include: committing a foul within 5 meters of the goal a player is defending if the referee decides that the foul prevented a likely goal, an act of brutality committed within 5 meters of the goal and tipping the goal box to prevent what likely would have been a scoring shot. If a penalty throw rebounds off the goal or the goalkeeper, play resumes. 

Personal fouls are the most serious types of fouls. When a player has committed three personal fouls during a game, they have to be substituted out of the match and are not allowed to return. 

Teams may substitute on the fly from the re-entry area in Olympic water polo during actual play, which is located at the corner of the pool in front of the team's bench. Teams are also allowed to substitute players freely after a goal is scored, during a timeout or between periods.