How much water should I bring hiking with a dog?

Working from roughly 250 to 500 ml per hour of active hiking for a medium dog, a planned three hour hike suggests bringing at least 750 ml to 1.5 liters just for the dog, on top of whatever water you are carrying for yourself. A larger dog, a particularly hot day, or a route with significant elevation gain all push toward the higher end of that range, sometimes beyond it.

Hot weather, high humidity, and challenging terrain that increases a dog's exertion level all raise water needs considerably above a baseline calculation done for mild, easy conditions, sometimes doubling the amount needed compared to a cool, flat, easy route of the same duration. Checking the weather forecast and elevation profile before the hike helps set a more accurate water target than a single fixed number applied to every trip.

Hikes commonly run longer than planned due to a wrong turn, a scenic detour, or simply moving slower than expected, and running out of water on the trail with no reliable source nearby is a genuinely risky situation, especially in hot weather, so treating the calculated amount as a minimum rather than an exact target and adding a real buffer matters more here than for most other travel scenarios.

A collapsible bowl that packs down small, or a specific dog hydration pack with a built-in bladder and drinking attachment, both work well for offering water during regular short breaks rather than waiting until a dog shows obvious thirst. Offering water every 30 to 45 minutes during active hiking, rather than only at longer rest stops, keeps hydration steadier through the day.