AskPatty's Tips for Driving with Dogs -- Tip #10
DO: Bring a complete traveling kit, including water.
In addition to travel papers, food, spill-proof water bowl, leash, a waste scoop, plastic bags, grooming supplies, medication, and a pet first-aid kit, pack a favorite toy or pillow to give your pet a sense of familiarity. Hollow toys you can stuff with food are ideal for quiet time in the car, campsite, or hotel.
When it comes to water, the ASPCA suggests you bring your own: Opt for bottled water or tap water stored in plastic jugs. Drinking water from an area he's not used to could result in tummy upset for your pet.