Some dog care experts recommend giving pet dogs filtered or bottled water but I give Gracie regular tap water. I am, however, a little obsessive about making sure she always has fresh, clean, cool water. I usually change Gracie's water at mealtimes and every time she drinks from her water bowl (that's not very often; maybe once or twice a day). I'm especially careful to change her water after she takes a drink after playing outside. That's when she slobbers into her bowl, so it would be gross not to change her water then.
I've always used a stainless steel water bowl (pictured above) since it's easy to clean and can be sanitized, in the dishwasher or with boiling water, if needed. More often I wash it by hand with hot water and dish soap (and rinse it thoroughly) just before feeding Gracie her breakfast and dinner. I wash Gracie's water bowl at least once each day.
I ALWAYS bring a filled water bowl outside when Gracie and I play --- even in the winter.