For sports enthusiasts who are looking to learn a new sport, the basic rules of water polo are easy to learn. To play, you must have at least 14 people, with each team having 7 members. This means that there will be 6 field players and 1goalie for each team.
Each game lasts about 45 minutes, with the game consisting of 4 seven-minute quarters. If a stop clock is used then these quarters will generally last around 12 minutes. However, most games use running time, which makes the quarters significantly shorter.
Scoring is extremely easy. For every goal, the team receives one point. Usually a team will only make 6-15 goals per game, but there are usually more shots taken than that. The skill level of the goalie can make or break a team and determine whether or not the game will be exciting because there were will be plenty of shots taken but very few will make it into the goal. Field players can only use one hand to move and shoot the ball.
A water polo field of play is a 30 meter x 20 meter pool, if going by FINA rules. High school rules have the field of play as 25m x 20m. If the pool that you use is half-deep, players should try and avoid touching the bottom and instead tread water. Penalties occur if a member places their feet on the bottom of the pool.
Fouls are extremely frequent in this game. If an ordinary foul is committed, a whistle will be blown and the ball will be rewarded to the opposing team. After a foul, the other team is allowed a free throw. Any offensive member has a 3 second window to put the ball in play. An ordinary foul is generally any type of contact that is considered unreasonable. These types of situations include grabbing, sinking, reaching over the shoulder, splashing water in the face, kicking, touching the ball with two hands (except the goalie), placing feet on the bottom of the floor, and pushing the ball underneath when another player is attacking.
Major fouls are much more serious and will result in a 20-second ejection. If a player has three major fouls then they are taken out of the game entirely. A major foul includes aggressive fouls committed away from the action of the game, field player blocking with two hands, illegal substitution, disrespecting the referee, aggressive defending and reaching over the head.
When a team receives the opportunity to have a penalty shot, the shot is taken 5 meters away from the goal. However, penalty shots are generally only awarded when someone is in a strong scoring position. If a goalie pushes the ball underwater while being attacked or if a field player, when blocking, uses two hands then a penalty shot will also be awarded.
These are just the basic rules of water polo. There are other technicalities that exist that should be researched and understood prior to playing. Usawaterpolo.org is a great resource to use if looking for an in-depth look at water polo.