7 month old won't drink water

[randdom]

My little boy is 7 and a half months old. He is formula fed and I started weaning him at 6 months with a combination of purees and finger food. He is having 3 meals a day and doing reasonably well. As his food intake has gone up his formula milk intake has decreased which makes sense.

However the big issue is getting him to drink. He isn't getting as much fluid from formula and I have tried everything I can think of to get him to drink water. I have tried non-sip cups, free flow cups, doidy cups, normal plastic open top cups and bottles with no luck. Today he went from about midday until 6pm with only a few sips of water and maybe 30mls of formula which doesn't seem enough. I am offering regularly with no luck.

Does anyone have any suggestions?

Just stick with it! He will drink if he is thirsty. My DS didn't start properly drinking water until he was about 9mo I think. He simply wasn't interested. But as he became more capable of crawling for and using a cup by himself he seemed to become more accepting of water!
We tried a few cups to start with - doidy and several varieties of sippy cups. He is happy using anything now, but I do think those ones that have a "straw" are good, after all they are used to sucking a bottle so why not a straw? They seemed to be aimed at toddlers though so we didn't try those until after he was one. We have a Nuby one and one of those ones with his name on from Debenhams.