World Aquatics Rules for Water Polo Goals
WP 2.1 Two goal posts and a crossbar, rigidly constructed, rectangular with a dimension of 0.075 metres facing the field of play and painted white shall be located on the goal lines at each end, equal distances from the sides and not less than 0.30 metres in front of the ends of the field of play.
WP 2.2 The inner sides of the goal posts shall be 3 metres apart. When the water is 1.50 metres or more in depth, the underside of the crossbar shall be 0.90 metres from the water surface. When the water is less than 1.50 metres in depth, the underside of the crossbar shall be 2.40 metres from the floor of the pool.
Link to Worlds Aquatics Water Polo Rules