The standard physical chemistry and thermodynamics literature states that water expands upon freezing due to the crystalline structure of ice (hexagonal ice I_h), which occupies approximately 9% more volume than liquid water at the same mass. This expansion is treated as an intrinsic property of the water molecule's phase transition, independent of the container material.
As stated in typical references:
The density of liquid water at 0°C is approximately 999.8 kg/m³.
The density of ice...