Barriers include forgetting or being inconvenient to bring a bottle out, favorite drink already being filled in a bottle for sale, shops refusing to sell their drinks in our own bottle (for food safety reason), lazy to wash the water bottle, more than 1 people drinking (cannot share bottle or cannot bring too many bottles out).
Suggestion for making reusable bottle-using a permanent habit: Source for collapsible cups and bottles to save space and add more convenience in bring out. Put multiple reusable bottles at different locations, e.g. at office desk, inside different bags. Increase taxes for bottled water.