Hi,
The best thing to do is just hang on in there, my ds also hated the taste for some time - its a totally new thing for them after all. Just keep offering it to him and eventually he will start to take it.
The key is not to give up or force him in any way, if he's thirsty he will drink - just offer it with every meal and when he's a bit bigger and getting snacks instead of milk, with his snacks too.
Take water out with you too, and you can give him a sip between bottles if necessary.
Don't worry, he will eventually catch on. Theres nothing to worry about unless of course he is becoming constipated.