Isn't it the same plastic as water bottles? Isn't PVC soft?

These two questions seem to be fairly popular when anyone comes across UPVC doors and windows.

Lets start with what is actually PVC?

We wont go deep into Chemistry of polymers. If you are into that kind of fun, here is a great source to get in-depth info about PVC: Raw PVC. More to the topic of PVC in a window aspect.

Standard PVC products are made from raw materials present in salt, petroleum and natural gas. uPVC products use the same ingredients but do not have chemicals, known as plasticizers, added to them during the construction process.

Short answer: No, it is not the same plastic as used in water bottles. it is a completely different polymer.

Isn't PVC flexible? PVC is. uPVC isnt.

PVC in its pure form is not suitable for use in windows. Additives and stabilizers need to be added to the raw ingredients to stabilize the ingredients, making it possible to use the substance to manufacture uPVC windows and doors. The type of and quantity of stabilizers added varies depending on the window manufacturer. uPVC Windows are rigid and do not flex or bend.