Water

From UroWiki

As uromastyx come from a naturally dry part of the world, they normally require low humidity levels of less than 40%, although they can survive quite easily in levels up to 60% for a period of time. Studies of wild uromastyx populations have shown that the humidity level in a hide area can be as low as 10%, and generally around 20%. High levels of humidity (60% or more) around the uromastyx can cause respiratory infections and eventual death.

Water bowl

Do not provide a water bowl inside your enclosure, as this can raise humidity to dangerous levels. The uromastyx get all their required water intake from the fresh vegetables they eat, and have no need for (and have not been observed to drink) standing water. Misting is also not recommended.

Bathing

Some sources recommend bathing your lizard as a means to clean it and to assist shedding. However, you should never bathe your uromastyx, as the water temperature may be too low for your uromastyx' needs; additionally, water can get trapped between the spines of its tail, which can eventually cause tail rot, a thoroughly unpleasant condition.