Hi Deanna. Hard plastic has a habit of freezing and getting brittle. Happens to PVC pipe also. I'm not sure what part you mean as most have a rubber hose with metal connectors. I've seen those plastic plugs that screw into the tank when you remove it for filling that will crack and break in the winter. If your kids are grown and gone then the only other culprits left are ghosts. Maybe your place is haunted.