Go to this page and read EVERYTHING! This is the most extensive Water dRagon page currently on the net. (although the cage reccomendations are too small. )
http://www.icomm.ca/dragon/
Absolute Basics:
6 foot tall x 4 foot wide x 2.5 foot deep MINIMUM CAGE DIMENSIONS. (Babies can be kept in a 75 gallon. minumum but will outgrow it within 3-5 months.) A cage this size in IMPERATIVE for the dragon to thrive. Should not be kept in pairs, but does ak in trios of 1:3. Add on 1.5 foot MINIMUM to the cage for each additional dragon.
Too small of a cage results in snout rub (Look at almost ANY water dragon pic on the net and you will see snout rub.) and stunted limbs. (These lizards NEED to climb and get a lot of excersize.)
Requires UV lights! 84 F- 88 day temps with a basking spot of 91. and a cool end of 75.
Needs daily feeding, diet of mice, feeder fish, crickets, superworms, silkworms, butterworms, earthworms, mealworms, VARIETY IS THE KEY! Some dragons will take small amounts of fruit. An adult dragon will cost you $2-$5 a day to properly feed it if you buy from a pet store. Starting your own mice/insect colonies is a better idea economically. You will also need a calcium supplement 2-4 times a week and vitamin supplement once a week.
Another note: buy captive bred!!!!!!!! I have spoken with 100's of water draogn owners and 99% of wild caught water dragons have or will get a serious health complication.
Expect to spend $1000-$3000 for permanent housing set-up.
They are a time and space demanding lizard, but if you can provide all they need they are AWESOME pets.