Metal pipes used to carry water sometimes burst in the winter. This is because

Metal pipes burst in winter primarily because water exhibits anomalous expansion upon freezing. Unlike most substances that contract when cooling, water expands by approximately 9% to 10% of its volume as it transitions from a liquid to a solid state [1][t1][t3]. This expansion occurs due to the formation of a crystalline hexagonal structure in ice that occupies more space than liquid water [t1][t2]. When water is confined within a metal pipe and freezes, this increase in volume exerts a tremendous bursting pressure—up to 140 kg per square cm—against the internal walls of the pipe [c1][c4]. While the metal pipe itself typically contracts slightly due to the cold, the internal pressure from the expanding ice exceeds the tensile strength or ductility of the pipe material, leading to ruptures at joints or weak spots [t1][t3][t7].

Sources

1. [1] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > PHYSICAL OR MECHANICAL WEATHERING > p. 39