Water pipes are made from rigid, unplasticized PVC. It's only flexible PVC (e.g. cable insulation) that contains plasticizers.
The most common water pipe in new construction is cross linked polyethylene. XLPE. It is stable, inert, and contains no plasticizers. PVC is often used for sewage drain pipes. Like the parent said it is the rigid crystalline kind typically containing minimal plasticizers tightly bound within the crystal matrix.