Rabbit urine vary in color from light yellow to brown, with all hues of orange and even red in between. It’s normal and not an observandum. The color comes from plant pigments, for example carotenoids. Some buns have more colored urine than other buns on the same diet. It’s not known why.
Here’s some good information on rabbit urine: http://rabbit.org/journal/3-1/red-urine.html
A rabbit should consume 100 ml water per day and kilogram body weight. A substantial amount comes from greens, so don’t expect them to drink this much if they are getting greens. It’s good you give them water in bowls, that encourages drinking.
It’s great that they are lots of hay! Hay is so important for buns it can’t be stressed enough. If their poop is good they are most likely well enough hydrated, the poop should not be desert-dry and crumble as soon as you touch it, it should hold together in round “pelleted” shape. Dehydration can cause a slowdown of the gut, so it’s good to keep an eye on size, shape, consistency, color and amount of poop.
If it’s very warm where you are you can check out our cooling-tips: https://binkybunny.com/BUNNYINFO/tabid/53/CategoryID/23/PID/940/Default.aspx