If you want to be absolutely certain, read the list of items that your airline does not allow on board. They usually post this list on the airline website and also on your ticket/itinerary printout. However, as long as the bottle is empty when you go through the security checkpoint, I don't see why anyone would confiscate it. Just leave the top off, and carry the bottle upside down, so it's obvious that it doesn't contain any liquid. They might still want to look inside it, but if it's empty then no big deal.
I looked on the TSA website, but nothing was mentioned about stainless steel bottles. So I wrote to them, and this was their reply:
Thank you for your e-mail.
The Transportation Security Administration's current security screening procedures require all carry-on luggage and accessible property be screened before passengers take them onboard an aircraft. Regardless of whether an item is on the prohibited or permitted items list, the Transportation Security Officers (TSO's) have discretion to prohibit an individual from carrying an item through the screening checkpoint or onboard an aircraft if the item poses a security threat.
Therefore, TSA security screening personnel make the final decision on whether to permit items like this into the sterile area of the airport.
Please visit our website at http://www.tsa.gov for additional information about TSA. We continue to add new information and encourage you to check the website frequently for updated information.
We hope this information is helpful.
TSA Contact Center
So, I still don't know whether my stainless steel bottle will be allowed. I have seached several web sites, and some people have been allowed to take theirs, providing they are empty, while others have had theirs confiscated, even though they were empty (sigh)
Holy moly, that's expensive! I've noticed the airlines have started charging separately for a lot of the things that used to be part of the ticket. Last time I flew to Europe, I saw the airline was charging extra for seats in the emergency exit row - because it has a few extra inches of leg room. It's only a matter of time before they start charging for the air supply on board :-)
I decided to leave my stainless steel bottle at home. Instead I took two empty plastic bottles. I don't like using plastic, but I decided not to take the chance that my metal bottle would be taken from me.
The TSA staff were very polite, and made the experience through the line short, and not too scary.
Unfortunately, the whole hassle with the baggage has made me decide to vacation closer to home in the future so we can drive to our destination. If more families do this the airlines will, hopefully, stop charging for extra baggage. At some point, they are going to realize they need passengers to fly their "friendly skies."
Jet Blue doesn't charge either, don't get me started on charging for luggage! Anyway, I have been through airports all over the US and although the TSA is supposed to be a Federal I haven't found any standardization. I had a tube of toothpaste in my carry on, it made it through the Austin, Ft Lauderdale,Burbank,Boston,Dallas Airports but was confiscated in Phoenix. Glad you had a good vacation.