I just read three different articles on this subject and it's not clear if disposable plastic bottles (bottles, not cups) are also banned. I'd argue this is one of the bigger problems as displayed by some of the images used in the articles, and personal experiences of travelling india and seeing miles of train tracks littered with plastic bottles.
The reason I mention this is that it may be directing action to local vendors, but not necessarily regional/national drink vendors.
- skip to point #23 on page 63 for the thing about banning plastic:
"We further direct that the use of disposable plastic glasses is prohibited in entire NCT, Delhi at hotels, restaurants and public as well as private functions. The NCT, Delhi shall take appropriate steps against storage, sale and use of such plastic material at above places and it shall stand prohibited w.e.f. 01st of January, 2017."
Note that this still mentions more about plastic cups, not bottles.
Also the title says "literally all disposable plastic" then in the article it says applies to cups, bags, cutlery.