If you still have a cold water tank and water pipes in your roof space, then any leak will cause serious damage to the ceilings, timbers, and lead to costly repairs.
Water tanks are likely to be made of metal, asbestos, fiberglass or plastic. If the tank is made of Lead or asbestos, then removal by a specialist company is likely to be required.
Replace asbestos and Lead water tanks with fiberglass or plastic tanks.
If you still have a cold water tank and water pipes in your roof space you should insulate around and over the tank to prevent freezing.
Pipes should either run under the insulation or be encased in proprietary foam pipe insulation.
If you still have a cold water tank and water pipes in your roof space and then introduce insulation, it is essential not to insulate under the tank.