How much water should my horse drink?

Short answer

Free-choice, clean, fresh water at all times — and more than most people think.

A 500 kg (1,100 lb) horse typically drinks 5–10 gallons (20–40 liters) per day, but intake can rise to 15+ gallons in heat, during work, or on dry hay (Merck Veterinary Manual; AAEP).

Water needs increase with sweat, lactation, heat, travel, and high-forage diets.

Real-Life Example

It’s winter. The trough looks full — but it’s ice-cold and partially frozen.

Your horse is eating dry hay and salt is being added to feed, but water intake quietly drops.

Less water + dry forage + salt = increased colic risk.

Checking water means more than “is it there?”
It means: Is it drinkable? Accessible? Palatable?

It Depends

Water needs change with:

• Temperature (hot or freezing conditions)
• Workload and sweat loss
• Salt intake
• Lactation
• Dry hay vs pasture
• Travel and stress

Some horses drink less if water is too cold, dirty, algae-filled, or unfamiliar (travel situations).

When to Seek Guidance

If you notice:

• Reduced manure output
• Dry, firm manure
• Lethargy
• Skin tenting (dehydration)
• Colic signs

Pause and contact your veterinarian.

If you’re unsure whether intake is adequate, monitor daily consumption for several days to establish a baseline.

Sources:
Merck Veterinary Manual – Water Requirements in Horses
American Association of Equine Practitioners (AAEP)
National Research Council (NRC)