For dogs and cats, and probably all other animals, don't put water in a plastic dish or bowl.
I'm not sure why; it's not going to kill them or anything, but apparently it makes the water less palatable to them. And cats of course usually drink far less water than they need, thus leading to kidney and bladder problems (and resultant high veterinary bills). With cats, one wants to encourage them to dine on water as much as possible.
A big glass or stainless-steel bowl gotten from the nearest thrift store for a dime or something, is best.
When watering the cats here--who drink water like there's no tomorrow (and hence no high veterinary bills for kidney or bladder problems)--I always put in two drops of grapefruit-seed extract per gallon of water, or thereabouts. I'm not sure why, but apparently it's good for them.