There are a few companies that will import "hot water urns" from England or Austrialia.
The real thing is that the restaurant business in the US just doesn't need hot water urns. Very few people drink hot tea, and coffee makers are designed to brew coffee, not just heat up water. Typically, the coffee vendor will take responsiblity for placing the coffee maker, keeping it working, and providing coffee for it.
It's unfortunate, because those hot water urns seem like they would make a handy HLT.