How much water does your horse need to drink every day to stay healthy and how much do water requirements increase in hot conditions or when working?

Ensuring adequate water intake is important for the optimal health and well-being of all horses. Some horses are more susceptible to becoming dehydrated and have a higher need for water.

A typical, idle 500 kg horse requires at least 25 litres (6.6 US gallons) of water per day.

In hot weather, horses may require 55 litres (15 US gallons) per day and they may need anywhere from 40 – 70 litres (10 – 18 gallons) per day when exercising.

Even if you provide your horse with constant access to fresh clean water, horses will not always drink enough water to avoid dehydration.

In particular, water intake should be intentionally encouraged in exercising horses, lactating mares, horses with gastrointestinal issues, and during both hot and cold weather.

This article discusses why adequate water intake is important, factors that can affect water intake, how to assess dehydration, and how to encourage water consumption in horses.

Importance of Water Intake for Horses

Water is one of the most important nutrients your horse requires in its diet. Water is indirectly involved in all physiological processes essential for life.

This includes biochemical reactions that take place within the body, as well as the ability to maintain and regulate the body’s internal temperature.

The average adult horse’s body is composed of approximately 70% water. [3][4] This water is distributed within the cells of the horse’s body, in blood, as well as within organs that contain fluid, such as the stomach and the bladder.

Inadequate water consumption can negatively impact your horse’s health for a number of reasons and can contribute to diminished exercise performance and impaired cognitive function.

Common signs of dehydration include sunken eyes, general dullness and loss of skin elasticity. Prolonged dehydration can lead to more severe outcomes, such as impaction colic and even death in extreme cases.

Horses experiencing gastrointestinal issues such as diarrhea should be closely monitored for signs of dehydration due to excess fluid loss.

Performance horses also need their water intake closely monitored. Performance horses have a high water requirement because of their exercise demands, variations in husbandry, and potential exposure to hot and humid environments.

Water Requirements

Water requirements for horses vary depending on age, digestive health, diet composition, body condition, activity level, and perspiration rates.

Horses on pasture obtain more water from their forage and require less drinking water. Conversely, horses consuming hay and grain will need to drink more water to replenish hydration status.

The estimated water requirement for a horse at maintenance consuming hay is approximately 50 – 60 mL/kg body weight daily.

For the average 500 kg horse, this is 25 – 30 L (6.6 – 8 US gallons) of water per day. [1][2]

Below are general guidelines to consider:

Physiological State Water intake (L) Reference
Maintenance (Moderate Climate) 7 L per 100 kg BW [14]
Maintenance (Hot Climate) 12 L per 100 kg BW [14]
1 Hour Post-Exercise 12 – 28 L [24]
Moderate to Heavy Exercise up to 90 L per day [16]
Lactation up to 75 L per day [16]


These are estimates of intake based on available studies. The values above do not indicate the amount of water that should be provided to the horse.

Horses should always have free access to unlimited water wherever possible.

Careful formulation of the diet can also be beneficial for supporting water intake, particularly in moderate to very heavy exercising horses and lactating mares.

You can submit your horse’s diet for evaluation by our equine nutritionists to develop strategies to support adequate fluid intake.

Hydration Status

Horses that are regularly exercised and competing at a high level, lactating, and/or travelling are at an increased risk of becoming dehydrated.

Dehydration occurs when the amount of water lost through feces, urine, sweat, and respiration is greater than the amount consumed through feed and water consumption.

Mild dehydration occurs when there is a loss of 5% of total body water. For the average 500 kg horse, this would be approximately 18 L of water. [5]

Mild dehydration can negatively impact performance, impair mental focus and cause the horse to tire more quickly.

A water loss of greater than 15% total body water can be fatal to the horse. [5] This is equivalent to a loss of 95 L of water for an average 500 kg horse.

Electrolyte Balance

Inadequate water intake can throw off electrolyte balance in the blood and within cells.

Electrolytes are essential minerals including such as potassium, calcium and magnesium that play a role in proper muscle contraction and nerve function. [6]

Horses with low electrolyte levels may experience the following symptoms: [6]

  • Fatigue
  • Muscle cramps and spasms
  • Tying up
  • Rapid heart beat
  • Low blood pressure
  • Neurological issues

Gut Health

Water intake is important to support gut health and digestive function. Horses that do not consume enough water are at greater risk for impaction colic and constipation.

The gastrointestinal tract functions as a reservoir for water during periods of exercise and when water is temporarily not available. [7]

If your horse does not have access to water for long periods of time, ingested food does not move through the intestines as quickly as it otherwise would. This is referred to as impaired gastrointestinal motility.

Research has found that a decrease in water consumption was the most commonly observed factor in horses preceding an episode of colic. [8] This is one of the reasons why sudden weather changes which affect water consumption can lead to adverse gastrointestinal conditions, including impaction colic.

Not drinking enough water can also contribute to gastric ulcers in horses. [9] The absence of water in the paddock has been identified as a factor that may increase the risk of ulcers.

Milk Production

Mares that are lactating require more water to support milk production. Lactating mares will increase their water consumption by 37 – 74% to ensure adequate hydration status. [5]

Mares that do not drink enough water may produce a lower volume of milk They may also produce milk that is of lower nutritional quality for the foal. [10]

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Assessing Dehydration in Your Horse

There are a number of ways to evaluate whether your horse is dehydrated including: [11][12]

  1. Monitoring the volume of water consumed
  2. Mucous membrane moisture, color, and capillary refill time (CRT)
  3. Manure consistency
  4. Skin pinch test
  5. Visual assessment (sunken eyes, dull appearance and/or drawn up flanks)
  6. Bloodwork

The best and most reliable method to assess adequate water consumption and hydration by the horse is to measure the volume of water consumed. [13]

This can be done manually by counting how many buckets of water the horse has consumed or by connecting the horse’s automatic watering bowl to an individual meter.

Mucous Membranes and CRT

Evaluating your horse’s mucous membranes and capillary refill time (CRT) is an easy way to assess hydration status.

The easiest mucous membranes to assess are the gums – you simply lift your horse’s upper lip to visualize the gums. To evaluate CRT, you’ll take your finger and blanch the gum surface. The capillary refill time is the time it takes for the gum color to return to normal.

Normally, the gums should be pink or light pink in color and moist to the touch. After blanching, color should return in <2 seconds.

When a horse is dehydrated, the gums will be pink or dark pink in color, but tacky or dry. The capillary refill time will also be prolonged, meaning it takes longer than 2 seconds for color to return to the blanched area.

Skin Pinch Test

The skin pinch test is another popular way to evaluate hydration status. However, this method is not the most reliable way to assess hydration status.

The method involves pinching the skin to form a tent at the base of the neck and releasing it. In a normal horse, the skin should return to its normal position immediately. If the skin remains tented, then the horse is presumed to be dehydrated.

However, time it takes for the skin to return to a normal position may also be affected by the site on the horse’s body where the test is performed, the moisture level of the horse’s coat, as well as the age of the horse. [13]

Factors that Affect Water Intake

The volume of water that a horse drinks is affected by a number of factors, including:

  • Water content of the diet: Horses consuming dry feeds such as hay will drink more water than those grazing on pasture which has a higher moisture content (up to 60-80%) [1][17]
  • Protein content of the diet: Excess protein in the diet results in excess nitrogen that needs to be excreted in urine which causes the horse to drink more water [18][19]
  • Season: Ambient temperature and pasture consumption changes throughout the year both affect water intake [20][21]
  • Water characteristics and availability: Water temperature, smell, taste as well as location and delivery method (bucket, trough or automatic drinker) can all affect intake [22][23][5]
  • Exercise level: Exercising horses require more water than those at maintenance to replenish fluids lost in sweat [24][25]
  • Size and body condition: Larger horses will require more water even under the same environmental and exercise conditions. [5] Overweight horses may require less water than a fit horse of the same weight because muscle contains more water than fat
  • Breed: Breed differences may affect water intake
  • Lifestage: Horses in lactation have a higher water requirement to support milk production [16]

These are all important factors to consider when trying to optimize water intake and delivery for your horse.

Tips for Encouraging Water Consumption

The following are eight simple and effective ways to encourage water consumption by your horse:

1) Increase your Horse’s Salt Intake

Salt intake is directly correlated with water consumption. Adding salt to a horse’s feed will increase its water intake by stimulating thirst.

A study found that doubling the salt in feed from 50 mg/kg body weight to 100 mg/kg body weight increased water consumption by 53%. [5]

The average horse should receive at least one ounce (30 g / 2 tablespoons) of loose salt in their daily feed. Larger horses and horses undergoing moderate or heavy work should receive a higher quantity of loose salt.

Free choice, loose salt should also be provided to your horse at all times. Loose salt is preferable over salt blocks as horses simply cannot meet their sodium requirement from a salt block.

2) Provide Electrolyte Supplements

Providing your horse with salt and water is typically adequate to replenish fluid loss for most horses at maintenance or those in light recreational exercise.

However, for horses undergoing more intense and frequent exercise, supplementing electrolytes is recommended to replenish the electrolyte minerals lost in sweat.

Horses at maintenance may also require electrolytes when temperatures are very hot and humid or in other situations when it is necessary to encourage greater water intake.

One study found that horses that ran 60 km on a treadmill drank more water when an electrolyte was added to their water (24 – 26 L) compared to providing water alone (12.2 L). Water intake was slightly higher when the electrolyte contained added sugar. [24]

A good electrolyte supplement should provide the minerals lost in sweat (sodium, potassium, chloride) in the correct ratio. Electrolytes should also contain some sweetener and/or flavouring for taste. [24]

Electrolytes should be supplemented in water; however, they can be top-dressed onto feed or syringed as a paste if water is freely available.

Horses may require training in order to drink water flavoured with electrolytes. To help your horse adapt, slowly add an increasing quantity of electrolytes to their water over 1 to 2 weeks.

Mad Barn’s Performance XL: Electrolytes supplement offers a convenient and effective way to re-establish electrolyte balance and prevent dehydration.

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3) Provide warm water during cold weather

When outdoor temperatures are cold, it is important to provide your horse with room-temperature water to encourage hydration.

Research shows that in cold weather, horses will drink more warm water (~ 20°C or 68°F) compared to icy, cold water (0°C or 32°F). [22]

Exercising horses also drink more water or electrolyte solution when it is warm in temperature compared to cold. [23]

In warmer weather, water consumption is similar regardless of whether the water is warm or cold.

4) Ensure clean fresh water is always easily accessible

Water should be freely available and accessible to the horse when stabled and outside in the paddock.

Water troughs in the paddock should be located in a way that allows for the maximum number of horses to drink at one time.

Horses that have to walk further to access water will drink less compared to horses that have water freely available nearby. [5]

The water provided should be clean to minimize adverse tastes and smells that can discourage consumption. Common smells that may negatively impact water intake by the horse are: [5]

  • Sulfates
  • Manure
  • Algae
  • Microbial by-products
  • Rotting vegetation

Water buckets and automatic watering bowls should be cleaned on a daily basis. Automatic watering systems should also be checked daily to ensure that they are working properly.

Outdoor water troughs should be cleaned at least every couple of weeks to remove debris.

5) Use Light-Coloured Water Buckets

Automated watering systems provide horse owners with convenience; however, horses appear to prefer drinking out of a bucket versus an automatic watering bowl. [27]

Research shows that among horses adapted to both systems, horses drank more water from a bucket (24 L per day) as compared to an automatic system (17 L per day). [15]

The colour of the bucket can also impact water intake. Horses drink more from light-coloured buckets (turquoise, light blue and light green) compared to dark-coloured buckets (green, yellow and red). [34]

Water consumption is greatest with turquoise buckets. [34]

Of the automatic watering bowls available, horses appear to prefer those with a float valve compared to those with a pressure valve. They also appear to prefer larger bowls to smaller ones. [28]

Flow rate in automatic waterers can also affect the volume of water consumed by the horse. A study found that horses drank the most when water was refilled at a rate of 8 L / min, as compared to a slow rate (3 L / min) or a fast rate (16 L / min). [27]

6) Allow access to pasture

Good-quality pasture can contain up to 80% water, with some variation depending on the type of grass and the season. [29][30]

When horses are out grazing on pasture, a large percentage of their water requirement is met by the water they are consuming in the grass.

A horse on pasture will require significantly less drinking water than a horse on hay, grains or a complete feed. [1][17] These feeds contain a higher percentage of dry matter compared to pasture grasses.

When seasonally available, and depending on the condition and health of the horse, you can increase your horse’s water intake by giving them the opportunity to graze frequently.

Note that pasture access should be limited or avoided for horses that are over-conditioned, have metabolic concerns such as Equine Metabolic Syndrome or Cushing’s disease with insulin resistance, or are at risk of developing laminitis.

7) Soak or Steam Hay

Soaking or steaming your horse’s hay can help to increase water consumption by boosting the moisture content of the forage. [31] Soaking hay increases moisture levels by a factor of 5 while steaming increases levels by a factor of 2.

Soaking lowers the sugar content of hay which has additional benefits for horses that need to lose weight or those with metabolic issues.

However, it can also decrease the mineral content of hay. It is generally recommended to soak hay for no longer than 30 minutes in warm water or 60 minutes in cold water. [31]

Steaming hay helps to reduce airborne particulates and allergens that can cause issues for horses with respiratory problems. However, steaming hay is labour intensive and requires the purchase of an expensive steamer.

8) Train horses to drink flavored water if travel is anticipated

Differences in the taste of water may negatively impact your horse’s intake and hydration status. This is particularly problematic for horses that are travelling.

It is recommended to get your horse used to drinking flavoured water prior to transport. This will help to offset any differences in the taste of the water they are used to and the potential novel water source at their destination.

Water can be flavoured with apple juice, Gatorade, commercial flavouring, an electrolyte product, or sugar. The flavour should slowly be added to the water in increasing quantity for 1 – 2 weeks prior to transport. [5]

Horses appear to prefer sweet flavours to other tastes. [32][33] However, high quantities of sugar are not suitable for all horses.

If you have a metabolic horse, speak with a nutritionist to learn about appropriate flavouring solutions and safe quantities of sugar.


We’ve all heard the famous saying: “You can lead a horse to water, but you can’t make them drink“.

However, there are certain factors that can both negatively and positively impact water consumption in the horse.

Ensuring that your horse is well-hydrated is of utmost importance for maintaining optimal physical performance and health; especially if they are undergoing moderate or heavy exercise or live in hot and humid conditions.

Giving your horse free access to clean fresh water and providing additional salt and electrolytes are the simplest ways to encourage adequate water intake.

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  1. Sweeting, M.P. et al. Social Facilitation of Feeding and Time Budgets in Stabled Ponies. J Anim Sci. 1985. View Summary
  2. Groenendyk, S. et al. External Balance of Water and Electrolytes in the Horse. Equine Vet J. 1988. View Summary
  3. Julian, L.M. et al. Blood Volume, Body Water and Body Fat of the Horse. J Appl Physiol. 1956.View Summary
  4. Forro, M. et al. Total Body Water and ECFV Measured Using Bioelectrical Impedance Analysis and Indicator Dilution in Horses. J Appl Physiol. 2000. View Summary
  5. Cymbaluk, N.F. Water. In Equine Applied and Clinical Nutrition. 2013.
  6. Flaminio, M.J.B.F. and Rush, B.R. Fluid and Electrolyte Balance in Endurance Horses. Vet Clin North Am Equine Pract. 1998. View Summary
  7. Sneddon, J.C. and Argenzio, R.A. Feeding Strategy and Water Homeostasis in Equids: The Role of the Hind Gut. J Arid Environ. 1998.
  8. Kaya, G. et al. Risk Factors of Colic in Horses in Austria. J Anim Physiol Anim Nutr. 2009. View Summary
  9. Luthersson, N. et al. Risk Factors Associated with Equine Gastric Ulceration Syndrome (EGUS) in 201 Horses in Denmark. Equine Vet J. 2009.View Summary
  10. Alamer, M. Effect of Water Restriction on Lactation Performance of Aardi Goats Under Heat Stress Conditions. Small Rumin Res. 2009.
  11. Freeman, D.A. et al. Clinical, Biochemical, and Hygiene Assessment of Stabled Horses Provided Continuous or Intermittent Access to Drinking Water. Am J Vet Res. 1999.View Summary
  12. Pritchard, J.C. et al. Validity of a Behavioural Measure of Heat Stress and a Skin Tent Test for Dehydration in Working Horses and Donkeys. Equine Vet J. 2006. View Summary
  13. Pritchard, J.C. et al. Validity of Indicators of Dehydration in Working Horses: A Longitudinal Study of Changes in Skin Tent Duration, Mucous Membrane Dryness and Drinking Behaviou Equine Vet J. 2008.View Summary
  14. Pagan, J. Water most overlooked nutrient in horses. Feedstuffs. 2008.
  15. Nyman, S. et al. Water Intake and Fluid Shifts in Horses: Effects of Hydration Status During Two Exercise Tests. Equine Vet J. 2002.
  16. NRC, 2007 Nutrient Requirements of Horses, Chapter 7: Water and Water Quality. NRC. 2007.
  17. Scheibe, K.M. et al. Water Consumption and Watering Behaviour of Przewalski Horses (Equus ferus przewalskii) in a Semireserve. Zoo Biol. 1998.
  18. Ragnarsson, S. and Lindberg, J.E. Nutritional Value of Timothy Haylage in Icelandic Horses. Livest Sci. 2008.
  19. Hyslop, JJ. Relationship Between Crude Protein Intake and Water Intake in Forage Based Equine Diets. BSAP Occas Publ. 2004.
  20. Cymbaluk, N.F. Cold Housing Effects on Growth and Nutrient Demand of Young Horses. J Anim Sci. 1990. View Summary
  21. Geor, R.J. et al. Adaptations to Daily Exercise in Hot and Humid Ambient Conditions in Trained Thoroughbred Horses. Equine Vet J. 1996. View Summary
  22. Kristula, M.A. and McDonnell, S.M. Drinking Water Temperature Affects Consumption of Water During Cold Weather in Ponies. Appl Anim Behav Sci. 1994.
  23. Butudom, P. et al. Rehydration Fluid Temperature Affects Voluntary Drinking in Horses Dehydrated by Furosemide Administration and Endurance Exercise. Vet J. 2004. View Summary
  24. Lindinger, M.I. Sweating, Dehydration and Electrolyte Supplementation: Challenges for the Performance Horse. In: Proceedings of the 4th European Equine Nutrition and Health Congress. 2008.
  25. Kingston, J.K. et al. Use of Dew-Point Hygrometry, Direct Sweat Collection, and Measurement of Body Water Losses to Determine Sweating Rates in Exercising Horses. Am J Vet Res. 1997. View Summary
  26. Dusterdieck, K.F. et al. Electrolyte and Glycerol Supplementation Improve Water Intake by Horses Performing a Simulated 60 km Endurance Ride. Equine Vet J. 1999. View Summary
  27. Nyman, S. and Dahlborn, K. Effect of Water Supply Method and Flow Rate on Drinking Behaviour and Fluid Balance in Horses. Physiol Behav. 2001.
  28. Krawczel, P.D. et al. A Note on the Preference of Naïve Horses for Different Water Bowls. Appl Anim Behav Sci. 2006.
  29. McMillen, W.N. et al. Chemical Composition, Grazing Value and Vegetative Changes of Herbage in a Typical Plains Pasture. J Anim Sci. 1943.
  30. Meissner, H.H. and Paulsmeier, D.V. Plant Compositional Constituents Affecting Between-Plant and Animal Species Prediction of Forage Intake. J Anim Sci. 1995.
  31. Bochnia, M. et al. Effect of Hay Soaking Duration on Metabolizable Energy, Total and Prececal Digestible Crude Protein and Amino Acids, Non-Starch Carbohydrates, Macronutrients and Trace Elements. J Equine Vet Sci. 2021.
  32. Danel, J. and Merkies, K. Discrimination and selection by horses of sucrose solution. J Equine Vet Sci. 2009.
  33. Randall, R.P. et al. Response of horses to sweet, salty, sour and bitter solutions. J Anim Sci. 1978. View Summary
  34. Yildirim, F., and A. Yildiz. Water bucket colour preferences in horses. Australia Journal of Veterinary Sciences 52(2). 2020.
  35. Moore-Colyer, Meriel Jean Scott. The Effect of Five Different Wetting Treatments on the Nutrient Content and Microbial Concentration in Hay for Horses. PLoS One. 2014; 9(11): e114079. View Summary