housing arangments.

Can i house a juvenile ball python and a juvenile chinese water dragon together?

Absolutely NOT.
   
Never house different species in the same enclosure, and never house multiple snakes together. (Garter and ribbon are exceptions to this rule, as baby garters do best in groups).
   
First, your ball python requires an environment of 80F, with a 90F basking spot--which is similar to the water dragons, but the ball python needs 60% humidity, and the dragon needs 80%.
   
Water dragons love water, and will get it everywhere. Ball pythons readily develop skin infections when exposed to wet bedding.
   
Water dragons will instinctively fear snakes, and your dragon is likely to viciously attack the snake when it realizes it cannot escape from it.
   
While ball pythons have a reputation for being picky, they are still predatory snakes, and a water dragon just might be an acceptable meal one day.
   
On top of that, they might transmit parasites or bacteria that may make the other sick, because they come from different parts of the world.