Abstract: A pool unit including a pool shell, which has a wall, and a bracing structure bracing the wall to curve inwardly. The pool shell is fillable with water to straighten the wall to form a straight wall.

Abstract: A pool shell including a wall, a floor and a region of curvature running along a bottom of the wall and connecting the wall to the floor. A fastener-receiving formation, on an exterior of the region of curvature is for rigidly connecting the bottom to a support. Also discussed is a swimming pool including a pool shell, having a wall and two or more upright supports. The wall has a top, a bottom, a first elongate stiffening portion and an exterior. The upright supports are spaced along the exterior. The first elongate stiffening portion runs along the wall and is positioned more than 250 mm from each of the top and the bottom. Each of the upright supports are rigidly connected to the first elongate stiffening portion and at least one of the top and the bottom, and predominantly formed of elongate rigid members.

Abstract: A pool shell including a wall, a floor and a region of curvature running along a bottom of the wall and connecting the wall to the floor. A fastener-receiving formation, on an exterior of the region of curvature is for rigidly connecting the bottom to a support. Also discussed is a swimming pool including a pool shell, having a wall and two or more upright supports. The wall has a top, a bottom, a first elongate stiffening portion and an exterior. The upright supports are spaced along the exterior. The first elongate stiffening portion runs along the wall and is positioned more than 250 mm from each of the top and the bottom. Each of the upright supports are rigidly connected to the first elongate stiffening portion and at least one of the top and the bottom, and predominantly formed of elongate rigid members.

Abstract: A valve 10, for relieving ground water pressure on a swimming pool for containing pool water. A body 30 defines a flow path. An element 20 is mounted to be moved in a direction from a position, in which at least one feature 22 of the element co-operates with at least one feature 33 of the body to form a sealing arrangement to block the flow path to retain the pool water, to a position in which the flow path is open to allow ground water into the swimming pool. The sealing arrangement defines an effective area over which the ground water pressure acts to drive the element in the direction, and an effective area over which pool water pressure acts to drive the element opposite the direction. The co-operable features are configured such that a ratio, of the effective area over which the ground water pressure acts to the effective area over which pool water pressure acts, has a value of at least 0.9.

Abstract: A valve 10, for relieving ground water pressure on a swimming pool for containing pool water. A body 30 defines a flow path. An element 20 is mounted to be moved in a direction from a position, in which at least one feature 22 of the element co-operates with at least one feature 33 of the body to form a sealing arrangement to block the flow path to retain the pool water, to a position in which the flow path is open to allow ground water into the swimming pool. The sealing arrangement defines an effective area over which the ground water pressure acts to drive the element in the direction, and an effective area over which pool water pressure acts to drive the element opposite the direction. The co-operable features are configured such that a ratio, of the effective area over which the ground water pressure acts to the effective area over which pool water pressure acts, has a value of at least 0.9.