4yo wont drink water

We have been dealing with this for a little while, but now the dayhome is mentioning it as well. Our son refuses to drink water, and he will often pretend to drink from his water bottle to make it look like he's drinking. We have been doing the big boy cup for 2 years now, but only at the dinner table. I now only give him water in the big boy cup, both trying to encourage, and so he can't fake it. It semi works, because I'm a bit more stern about it than mom, but that one small kiddie glass of water will take him 3 hours to drink.We used to give him a juice box a week as a treat, but we ended that 2 weeks ago. He also loves milk, but we have cut that down to just in the morning.Now he will go all day without drinking a drop and it's getting frustrating and worrying. I don't want to use scare tactics, but a friend of ours recommend telling him if he doesn't drink up we will take him to the doctor. If he doesn't start drinking soon, start packing up as if your going tot he doctor, even so far as putting him in the car and driving.ideas? via /r/Parenting http://ift.tt/2fM589q