While tap water is not generally recommended for consumption, ice is generally safe in Thailand and bottled water is ubiquitous and cheap.
If you are concerned, you can always stick with Thai beer, its nearly as cheap and the high alcohol content of Thai beer ensures that any germs aren’t likely to survive; Singha (pronounced “Sing”) and Chang (which means elephant) are the two most popular.
Fruit smoothies and fruit juice are both very popular: smoothies made with fresh fruit and sugar syrup are blended with ice that is generally safe to consume.
Coconut milk is another safe option as the coconut is simply cracked open from the top and served whole with a straw. Thai ice tea is served with condensed milk, which gives it a
Thai ice coffee (
Finally, red bull energy drink was invented in Thailand and can be procured at 7-11 and mom and pop minimarts for 10 baht. There are other local brands, but taste and potency vary widely.