We have a friend travelling to India tomorrow for work. He’ll be there for 10 days, and I’m fairly sure this will be his first trip to a non-first world nation.
He’s in for a treat.
I’ve only been to India once, but I still think my advice is solid. If you want to avoid, or at least minimize, severe gastro, you need to a) go vegetarian (super easy to do in India, and also delicious), and when it comes to liquids, follow the three Bs. Everything you need to drink has to be either brewed, boiled, or bottled.
Masala Chai? Great. Pint of Kingfisher? Delicious. Can of Diet Coke? Tastes like home.
Glass of water in the hotel. Probably fine. Fruit juice made on the side of the road with ice? Your poor, defenceless western immune system is in for a tough 24 hours. Prawn curry in Hyderabad washed down with a cold glass of water deep within the slums? I’ll let your imagination fill in the rest.