Water Polo is considered by exercise physiologists to be the most physically demanding of all sports. Players cover up to 3 kilometers in the pool over the 1 hour 15 mins it takes to complete a game, as well as physical contact, both above and below the surface of the water.
Water polo rules are a combination of soccer, basketball, ice hockey and rugby. What is so different about Water Polo it is played in the water which makes it difficult for the two referees to see exactly what is going on.
It is played in a deep pool 30×20 meters, with a goal 3 meters (9 feet, 10 inches) wide and at least 0.9 meters (2 feet, 11 inches) above the water. The goal is marked by vertical posts, a crossbar, and nets, as in soccer and hockey.
For the men’s sport, the pool is 30 meters (98 feet) long and 20 meters (65 feet) wide.
Women play in a somewhat smaller pool, 25 by 17 meters (82 by 56 feet).
There are seven players per team, six swimmers and a goalie. The home team wears white caps, the visiting team blue caps, and goalies wear red caps with the number “1″ in white or blue.
A game begins with the ball in the center of the pool, and both teams sprint for it from their own goal lines. The ball can be advanced by passing with one hand or “dribbling,” swimming with the head above the water and the ball between the arms so it rides on the wave created by the swimmer’s head. No player except the goalie can hold the ball with both hands.
A game is divided into quarters ranging from 5 to 8 minutes in length, depending on the level of play. After a tie, there are two overtime periods of 3 minutes each. If the game is still tied after the overtime periods, teams continue to play 3-minute overtimes until there is a decision.
Water polo is a physical contact sport. The four rules which deal with this are:

-Impeding (swimming over someone)

-Pushing

-Holding (sinking and pulling back)

-Brutality

Impeding and pushing are considered minor or ordinary fouls. To hold, sink, or pull back an opponent not holding the ball’ is considered a major foul. With the exception of brutality, these rules do not apply when an opponent is holding the ball, i.e. they can be tackle
Major fouls are penalized by one minute in the penalty box, and a player is ejected after committing five personal fouls. A penalty shot, taken from the 4-meter line, is awarded for fouls near the goal that prevent scoring. For minor fouls, such as holding or punching the ball, a free throw is awarded from the spot of the foul. The player taking the free throw may pass the ball or drop it and begin dribbling. At least two players must touch the ball after a free throw before a goal can be scored.