25 litres... of water!

25 litres... of water!

Water is an important nutriment for equines, for example, crucial to digestion and thermoregulation.
A number of factors can provoke a “lack” of water in horses. It can lead to a decline in performance, a drop in the consumption of the feed ration, dehydration, and finally death...

Horses should have permanent access to fresh, clean, good quality water.

The horse’s body is constituted from nearly 65 % water. This signifies that a 600kg horse is composed from nearly 400 litres of water!

Did you know that the biggest fluid loss in the horse occurs through his droppings?
Then, in lesser quantities, through urines, evaporation, the respiratory system, sweating, and lactation.

Although daily maintenance requirements in water are estimated as being 50 ml/kg of bodyweight with a wide margin, horses of similar weight, fed a similar ration, may consume very different amounts of water.

What are the daily requirements in water for a 500kg horse?
For a 500kg horse at rest = 25 LITRES a day.

What are the other factors which influence water requirements?


The total amount of feed consumed and its composition modifies the horse’s total intake of water. A study has shown that ponies will drink 12 to 61 % extra water when they are fed uniquely hay than when they are fed forage mixed with cereals. Then, the salt and protein level of the ration has a direct positive correlation with water intake.
This confirms the importance of easy access to clean fresh water.


Horses adapt to outside temperatures and changes in the amount of water drunk are part of this adaptation process.
It has been noted that when the temperature is less than -8°C the drop in water consumed could be close to -14%, without a drop in the intake of the ration. In contrast, during high temperatures water intake can increase by 50%.
The temperature of the water also has its importance: a study demonstrated that at an outside temperature of 25°C horses preferred a water at 20°C to water at 10°C or 30°C.


Pregnancy doesn’t seem to impose an increase in intake above that for ordinary requirements per kg of bodyweight.

Lactating mares can drink 150 à 200 % more than the amount of water observed being consumed during pregnancy. We estimate that water intake considerably increases above ordinary requirements owing to the loss of fluid (milk) and the increase in feed consumed due to lactation.

However, lactating mares are generally fed more cereals/concentrate feed than when they are pregnant, this can attenuate the increase in water intake previewed because of lactation due to the lower water/feed ratio of cereals.


It has been observed that one month old foals are able to drink 3.9 kg of water daily in addition to more than 17.4 kg of milk and that they continue to increase their intake of water (5.5 kg a day) at 2 months of age without simultaneously reducing milk intake.

It’s therefore of primordial importance to facilitate access to water for the mare and her foal.


Whilst travelling, fluid loss in the horse is considerable. Providing water with a bucket must be envisaged for every horse being transported and must be carried out frequently (at least every 2 to 4 hours) depending on the meteorological conditions whist travelling.


The water requirements of horses working or competing are affected by a certain number of variables which have an influence over fluid loss due to transpiration and respiration.

The requirements in water for a horse in work vary between 36-92 litres a day depending on the working and climatic conditions.

Water alone can compensate for fluid loss in the majority of horses undertaking light or moderate efforts.


Horses who are working intensely not only suffer loss of fluids, but also a large loss of electrolytes. In this case, the horse should be supplemented in electrolytes in order to cover his losses.
The aim of supplementing in electrolytes is to encourage water intake and to partially restore electrolyte imbalance. (Refer to the notice on electrolyte packaging for information on their appropriate use).

Increasing water intake: How?

Researchers have demonstrated that a good number of measures can be applied to stimulate water intake: Opt for water buckets/water troughs over automatic water bowls.

if automatic water bowls are used, take the care to check the water flow rate: less than 7-8 litres/minute is insufficient. Indeed, a lower flow rate can favour the onset of colics, ulcers, myositis, etc.

Horses prefer temperate water (around 20 °C) rather than a cool or cold water.

Then, if the water comes from a spring or a well, it’s essential to carry out a chemical/microbiological analysis twice a year in order to determine if the water is potable.

In short…

    • A horse should have permanent access to fresh, clean, good quality drinking water.
    • Water requirements of a horse at rest: 25 litres a day
    • Water requirements of horses in work: a minimum of 40 litres a day (an increase of 50-100% compared to basic requirements)
    • Automatic water bowls: Check the flow. Ideally around 8L/min.
    • Cold temperatures: Pay careful attention, horses drink less: onset of colics, myositis, etc. Ideal water temperature : around 20°C
    • Water from wells: Carry out 2 analysis a year, or opt for mains water
    • Travelling: It’s imperative to offer water in a bucket every 2-4 hours.
    • Electrolytes: To be used during efforts leading to sweating, or during transportation

Pôle Santé Reverdy, Département Recherche & Développement, Juvigny-les-Vallées, France