I do use water dishes in my communal dwarf tarantula cages. But.... You live in Vancouver, I live in the Arizona desert. Yours can probably get all the moisture they need from their food, down here they need a little help with that. I do, however, use shallow water dishes (petri dishes), and boost the humidity but spilling more water into the substrate than in the dishes.I never use water dishes as they get water from their food and when I mist the tank.