he is not drinking

I have just moved Zenith to our new proporty yesterday.
And since then he has not had a drink...
Otherwise he seems to be eating ok (he hasnt stopped)
How do I know if there is a problem?

If you are in a "wet" area, he may be getting enough water on the grass. If not, then it may be he doesn't like the taste of the water where he now is. He will get used to it, but in the meantime can you put some apple cider vinegar in his water? I use 2 cups in 30 gallons. Sometimes it helps.

Make sure he is peeing ok, and watch the color of the pee, should be, well, yellowish. If it is brownish call the vet, his kidneys are having problems, and the vet might need to pour some water into him, either down his throat or with an IV.

To check him for dehydration, pinch a bit of skin on his neck (not hard, just to hold it pinched) then let go. If it stayes in a kind of pinch, he is dehydrated, if it goes back to normal, he is ok.

Thanx for that.
We have moved in to a much wetter area, although its only 20 min away from where he used to be, it rains more and is low lying ground.
Can you put molassis in the water? Because I don't know what apple cider vinegar is and I don't know where to get it

You can buy apple cider vinegar in any grocery store.

You could also put apple juice in the water. (If he likes apple flavor) I would say you could add molassass to the water, or a cheaper alternative, and it dissolves easier is maple syrup (which has molassass in it) Then I would add less and less of it daily to get him used to the water. Sometimes the stress of a move can get them not to drink for a day or two, and/or the "change" in water taste until they get used to it.

Yes, you can put molassas in some water. Most horses love it. Just put a dollop in the water and mix it around.
I use it at endurance rides to get horses to drink unfamiliar water and it works great!
Just don't make it permenant!!! To much molassas is not good! A bucket or two of molassas water is enough until he gets used to the water especially if the grass is very moist!
And like desertgal said check he's not dehydrated and is peeing ok! If not then call a vet!

You could also use Sprite; that's what we use when at shows. Sweetens the water just enough to entice them.

But I'd be inclined to think that your horse is getting plenty of water from the grass. There are times when I can go days without watering my stock if it's been raining here

I guess the consensus is "anything that horses might find yummy and masks the flavor of the water" :)

We used to use Gatorade (the powdered stuff).

Gatorade is very good for that sort of problem. It encourages the horse to drink, and also has electrolytes so it helps with dehydration. We used that for Jazz after he colicked and was reluctant to drink because his tummy was still tender.