Equine Hydration: How Much Water Do Horses Need?

How much water do horses need

We all know that horses need to have constant access to clean, fresh water but do we really know how much water they should be drinking every day? This is something that I didn’t know the answer to, so decided to research just how much they needed to drink every day. It took me a while to find the answer but I was surprised when I found out, not just how much they needed but how important it was.

As a general rule of thumb, a horse at rest needs to drink a gallon (4.5 liters) of water per 100 pounds of weight every day. This means that horses need to drink between 5 and 15 gallons (22.7 to 68.1 liters) of water every day, although this amount will increase if the weather gets hotter or your horse’s workload is high. 

As the weather starts to get warmer we all begin thinking out how much water our horses have which is no bad thing but it’s not something you should only think about in the warmer months. Yes, horses, just like us, will instinctively drink more when it’s hotter (and in fact horses are more likely to suffer from dehydration when the temperature is higher) but they often need more water during the winter than you might realize. During the spring and summer, the grass tends to have a lot more moisture which counts towards your horse’s water intake but during the winter the grass has lost this moisture, meaning that horses need to find the fluid elsewhere.

How much water do horses need?

The average horse, if there is such a thing, needs to drink between 5 and 15 gallons (22.7 and 68.1 liters) per day when at rest but this is only a rough guide and there are lots of independent factors that will play a role in how much an individual horse needs to drink. The climate, which is one of those factors, can affect how much a horse drinks as well as how much they need to drink. For example, if the weather is hot a horse will need more water, but if it’s cold (and the water temperature is cold too) then most horses will drink less, even though they’re likely to want more. 

While it stands to reason the harder a horse works the more they sweat and therefore the more water they need to drink but what you might not realize is that their fitness level will have an impact on how much water they need too. The reason for this is that the fitter a horse is the harder they work before they start to sweat.

Just as is the case with us, diet can play a role in how much water a horse drinks. If your horse is eating a lot of dry foodOpens in a new tab. (such as hay or grains) they’ll need to drink more water than if they were eating moisture-rich food (such as lush grass).

Make sure your horse always has access to water

Why is water so important to horses?

Horses are just the same as all other living creatures in that they need water to help them digest their food as well as for thermoregulation (the ability to regulate body temperature in part via sweating) and to support other essential life functions. 

Water plays an important part in the digestive system of any animal but because horses have a very delicate digestive system compared to most other animals, this role is even more important. Water, as well as other fluids, helps the food to travel smoothly through the horse’s stomach and intestines. This lowers the risk of impaction colic and helps to prevent other digestive ailments.

As well as helping to keep your horse’s digestive system healthy water is also crucial for a number of other body functions such as:

  • Blood flow – You might not realize it but 92% of blood is water (the rest is blood plasma) so it stands to reason that water is crucial for the proper function of the circulatory system.
  • Tears – While containing a certain amount of salt, tears are mainly water so without it, your horse won’t be able to produce tears, which are essential for keeping the eyes clean and free of debris.
  • Mucus – Like blood and tears, mucus is more than 90% water but while you might think your horse’s nose would be better off without it, it’s actually vital for your horse’s body function. It acts as a moisturizing and protective barrier that stops organs from drying out and bacteria from getting in. 
  • Waste – As part of the digestive system waste products (urine and manure) need to be removed from the body and water is vital for this role.
  • Sweating – If your horse doesn’t have enough water he can’t produce sweat when he needs to cool down, this means he’s prone to overheating which has its own set of problems.
Horse need to have constant access to water

How can you tell if a horse is dehydrated?

Dehydration can occur during strenuous exercise, in stressful situations, or even if a horse suffers from diarrhea, and if dehydration is left untreated can result in kidney failure so it’s important to recognize the signs as soon as possible.

The quickest way to tell if your horse is dehydrated or not is to perform what’s known as the ‘skin inch test’. The test or the capillary refill test. Both tests only take a few seconds and, although they’re not always accurate they can give you an idea of whether or not your horse needs more fluids.

Skin pinch test

Simply pinch a fold of skin then, after a couple of seconds release it, if the skin immediately regains its form your horse isn’t dehydrated but if it doesn’t then there’s a very good chance that he is. The longer it takes for his skin to return to normal the more dehydrated he is. If, after 10 to 15 seconds, the skin still hasn’t returned to normal you should call your veterinarian straight away, taking this long to regain its original form is an indication of severe dehydration.

Skin Return TimeFluid Level
Immediate Normal
2 – 4 secondsMildly dehydrated 
4 – 10 secondsModerately dehydrated
More than 10 secondsSeverely dehydrated

Capillary refill test

A healthy horse’s gums should be pink in color and moist to touch but if your horse is dehydrated they’ll lose color and often become more sticky to touch. You can easily test this by pressing your finger or thumb on your horse’s gum for a couple of seconds. Once you remove your finger the color should return within a second or two, if it takes longer then your horse may well be dehydrated.

Color Return TimeFluid Level
Up to 2 secondsNormal
More than 2 secondsDehydrated

All horses are different and two separate horses, both suffering from dehydration, may display varying symptoms which is why it’s crucial to know what your horse’s vital signsOpens in a new tab. are. Understanding these will give you a baseline to judge what is and what isn’t normal for your horse. This will then give you an idea of what to look out for. That said though typical symptoms of dehydration include:

  • Dull or sunken eyes
  • Red mucous membranes
  • Excessive thick saliva
  • Dark urine that’s often smelly
  • Dry skin
  • Loss of appetite
  • Dizziness
  • High fever
  • Lethargy
  • Depression
  • High heart rate
  • Excessive sweating/no sweating

As I say though the skin pinch test isn’t always accurate in diagnosing dehydration and if you’re not sure you should speak to your veterinarian for advice. They will be able to assess your horse and if necessary do a blood test to confirm if your horse is dehydrated or not.

What should you do if your horse is dehydrated?

Some people say that if your horse is showing signs of dehydration you should allow him to only drink a small amount of water at a time but this isn’t the case. Horses should always have access to as much water as they need.

If you even suspect your horse is dehydrated you shouldn’t hesitate and should act immediately, in part because most cases of dehydration can be fixed by simply offering your horse plenty of clean palatable water. You might want to add some electrolytes to your horse’s water too, these will help him to replenish the minerals that he’s lost.

If, however, your horse is more than 8 to 10% dehydrated (more than 10 seconds in the skin pinch test) you should immediately call your veterinarian who will probably give your horse fluids via an IV drip.

What can you do to ensure your horse drinks enough?

We’ve all heard the 12th century proverb ‘you can take a horse to water but you can’t make him drink’ but there can often be a lot more truth in this than you might realize. If your horse is a fussy drinker it can be worrying but there are a number of things you can do to encourage your horse to drink more.

In most cases making sure your horse always has access to clean, fresh and palatable water is enough, but you should also scrub the buckets or trough regularly. If the water is dirty it’s likely to smell which will, understandably, put your horse off of drinking it.

While you might not realize it, the temperature of the water can make a difference too, especially during the winter. Recent evidence has shown that when the weather is cold horses prefer their drinking water to be around 68°F (20°C). You can wrap bubble wrap and a blanket around buckets and troughs to keep the water warm or, if you have an automatic water bowl, make sure the pipes are buried underground or wrapped in insulation.

Horses prefer the water to be warmer in the winter

Salt is a crucial element of a horse’s diet and can play a bigger role in their intake of water than you might think. A correct salt (or sodium) balance helps to regulate a horse’s thirst response and therefore how much water they drink. This is why you should either give your horse a salt block designed for horses or add a salt supplement (or loose salt) to his feed. 

If your horse still seems reluctant to drink you can try soaking their hay for between 10 to 12 hours will help to increase their intake of water. You could also add wet food to their meal such as soaked sugar beet, if it’s been soaked for around 24 hours 80% of the sugar beet can be water, so that can be a lot of water.

It’s important to monitor how much your horse drinks but don’t scrutinize it, the reason I say this is because horses don’t always drink the same amount every day. It’s better to look for signs of dehydration rather than watching how much your horse drinks. After all, it’s recently been discovered that horses will only spend a total of five minutes drinking every day, and when you consider that they don’t do this in one go but throughout the whole day it’s not really practical to watch how much your horse drinks.

How do you keep a horse hydrated while traveling?

If you need to transport your horse over a long distance then it can be difficult to keep them hydrated during the journey. This is one of the reasons why it’s crucial to make regular stops, doing so every two to three hours will give your horse a chance to drink. It’ll also allow him to stretch his legs (and you to stretch yours) and make the whole journey much easier for you both.

Giving him access to soaked or compressed hay throughout the journey will also help to increase his fluid intake. If you’re traveling to an area that has strange tasting or smelling water (at least in your horse’s eyes) you can use soaked hay to disguise the taste and therefore keep his fluid levels up.

Make regular stops if you're traveling long distances with your horse

There are two things to consider when using the same bit for multiple horses, the fit of the bit and any health issues the horse has. When it comes to the fit, it’s crucial that it’s right for both horses and doesn’t pinch at all. That said though if one of the horses has a contagious health issue they will pass it on to other horses using the same mouthpiece. With this in mind, you can use the same bit but it’s not advisable.

How long can a horse last without water?

Water is so important to all living creatures and horses are no different and they can only survive for three to six days without it. That said though after three or four days they may refuse to drink water. If the horse doesn’t get fluids at this stage their organs will begin to shut down and suffer irreversible damage.

Do foals need water or do they get enough fluid from their mothers?

While foals get a lot of their daily fluids from their mother you might be surprised to know that, from as early as one week, they will choose to drink water on their own. At this stage, they can drink around a gallon of water a day and a further four gallons of milk from their mother.

Can horses drink too much water?

Some conditions such as Equine Cushing’s DiseaseOpens in a new tab. can cause polydipsia which is an ailment that causes horses to drink excessively. If nothing is done about this it can put undue stress on the kidneys as well as dilute electrolytes in the horse’s body which can make it harder to regulate body temperature. Generally, healthy horses don’t excessively drink.

Further reading

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