L.S.
he is only one. Don't force him. We use sippy cups here and also the sippy cups with straws. My daughter is 19 months old now and can use a cup but prefers using straws. Don't make a big deal about this or it will become an issue. Just give him a sippy cup to play with and put some water or water/ juice in it and eventually he'll start taking sips from it. He is only a year!!
What is the big deal?? Also, you can stick him in the bathtub with clean water and see if he will drink the water from a cup in the bathtub, using the clean water from the spout. My daughter has been doing this for ages. It is fun for her and she drinks tons of water this way.