RULES IN BRIEF Swimmers must not touch the bottom or sides of the pool but tread water or swim throughout the match Swimmers must not hold on to the goalposts for a rest Clenched fists are banned Only goalkeepers may touch the ball with two hands The ball must not be held underwater The attack must shoot at goal within 35 seconds If 35 seconds expire without a shot, the opposing team is awarded a free throw, or throw-in, to begin its own offence Impeding an opponent who does not have the ball or pushing off an opponent is a foul A foul inside the four-metre line results in a penalty throw There are three types of foul; ordinary, exclusion and penalty Exclusions last 20 seconds An offside rule applies; players must be behind the line of the ball before passing the two-metre line of the goal they are attacking Goalkeepers may catch, hold or throw the ball with both hands inside their four-metre lines and must never cross the halfway line Kicking is a foul that results in exclusion Bleeding players must immediately be substituted