Are these new bottles safe to fill up half...
Are these new bottles safe to fill up half way and put in the freezer overnight?
The Nalgene Tritan bottles can withstand temperatures from -40 to 212 degrees Fahrenheit. I would allow a little room for expansion like you mentioned.
I do this all the time and you can fill it up about 3/4 of the way and have plenty of room for expansion as Jeff noted.