Westfalia Tank Water Filler Key A plastic key for Westfalia tank water inlet filler. Only for the inlet with the key hole; not for inlets with the metal lock underneath a hinged flap. Some of the earlier models came with a plug style lock and key inside the filler hose. (This style filler plug and lock is no longer available.) However if you want to update the entire - we manufacture these as well. We can also assist you with installation as well as acquiring all the necessary parts you will need.