Unless they're specially branded Keep Cups that reduce the likelihood of catering staff getting burned.
Irish Rail's image as a purveyor of clean, eco-friendly transportation has been somewhat sullied by a recent scandal over reusable cups. The company has changed its policy and said that passengers cannot use their own cups on board its trains anymore. The reason? It's a health and safety hazard. From the Guardian's report:
Various passengers watched in outrage as staff used a disposable cup to measure out the hot tea or coffee, dump into their reusable cup, and then toss the cup. On one occasion, an empty cup was tossed for no apparent reason at all, although it was clarified later that "catering staff tally the number of sales with the number of cups left" (via Irish Times).
"The reasons that we cannot permit [reusable cups] is because all sizes do not fit under the spout and also closing mechanisms can vary," the company tweeted on Monday. Different sized cups, it said, could lead to catering staff being burned.
The company claims to offer a happy medium: buy our branded Keep Cup and we'll fill it with no issues. But should a passenger show up with the same size, unbranded Keep Cup (or any other brand, for that matter), staff won't accept it. Too many unknowns with the closing mechanisms – but then why not just hand over to the owner to close, as they do at Starbucks and virtually every other coffee shop I've been to?
I'll be surprised if Irish Rail's stance holds up to public scrutiny. It seems so very backward for 2019. There are occasionally times when I encounter people unwilling to refill my water bottles and containers, but usually when I go a step higher along the chain of command, I get permission for a refill. No company wants to be associated with a reluctance to embrace reusables; it's such low-hanging fruit in the big picture. We'll see how this plays out.