Would You Drink It?

Have you ever taken a really good look at all of your horse's water sources, whether he is drinking from a large tank, pond, or automatic waterer? Have you asked yourself, "Would I drink this water? Do I really expect my horse to drink it?" If you're looking at water that is full of debris, algae, insects, or water that has a weird color or odor, then most likely you wouldn't drink it. And your horse shouldn't be expected to drink it either. Supplying fresh, clean water to your horse all the time is one of the most important things you can do to help him stay healthy.


Many labs have a standard water quality test, which usually evaluates water for human consumption. This standard test, which generally includes testing for total dissolved solids (TDS) and bacterial counts, costs on average $10-$50.

"Water is the main nutrient that horses must have," says Bob Coleman, PhD, PAS, associate professor in the Department of Animal Sciences and equine extension specialist at the University of Kentucky. "It's the one nutrient that we take for granted, yet it should be the first one we should worry about."

It's important to remember that merely supplying the water might not be enough. Making sure the horse will drink it, and that the water is safe and free of toxins, is of utmost importance.

The Need for Water

The general rule of thumb is that for every 100 pounds of body weight, a horse should have one gallon of water per day, according to Coleman. However, several factors can increase water needs, and not every horse is the same. For instance, if a horse is sweating a lot due to exercise or because it's hot outside, then he would need to replace lost water and possibly electrolytes. The exercising horse's water needs can increase by 20-300%, says Kent Thompson, PhD, Buckeye Nutrition's Director of Equine Nutrition. In addition, a lactating mare or one in late gestation needs more water.

Forage can make a difference on water consumption, according to Ann Swinker, PhD, associate professor in animal science at Pennsylvania State University and an extension horse specialist. Horses on pasture will be meeting some of their water needs through the water in the grass. However, those fed primarily dry matter, such as hay, need to drink more. Coleman says horses being fed alfalfa hay, in particular, need more water to get rid of excess nitrogen consumed when fed this high-protein forage.

If a horse's water needs are not met, dehydration can occur. A horse can die in two to three days if he gets severely dehydrated, says Swinker. Signs of dehydration include an unjustifiable loss of body weight, fever, increased respiratory rate, slow capillary refill rate, lethargy, lack of appetite, dry mucous membranes, a sunken look to the eyes, and a decreased ability to perform. A simple test for dehydration is pinching the skin into a tent. If the skin doesn't snap back within two to three seconds, the horse is dehydrated.

When Water Becomes Unsafe

There is no 100% pure water source. All water contains a variety of minerals and other substances, but not all of these are dangerous. Drinking water can be compromised in a variety of ways, including damage to wells or pipes or disassembly of the water supply system, contamination of ponds or streams, flooding, etc. You should become suspicious of contaminated water if your horse suddenly stops eating or drinking; if there is a noticeable change in the water's color, odor, or taste; or if multiple animals or people drinking from the same source becomes sick. Humans are more susceptible to most toxins and contaminants than horses, says Swinker.

If you're using city water, most likely it is perfectly safe for your horses to drink since humans are drinking it. Monitoring for contaminants is not often necessary with city water, which is not usually susceptible to variations in mineral levels.

Following are some common contaminants found in problem water.

Total Dissolved Solids--Wells will occasionally need monitoring for bacteria counts and total dissolved solids (TDS), which are inorganic and organic solids dissolved in the water. According to Feeding and Care of the Horse by Lon D. Lewis, DVM, PhD, Dipl. ACVN, "The single most reliable indication of water quality is the amount of total dissolved solids in the water." Lewis states that 1,000-3,000 parts per million (ppm, or mg/liter) of TDS is satisfactory for all livestock and poultry. Water with 3,000-5,000 ppm TDS can cause temporary diarrhea or might be refused by animals not used to this amount of TDS. Water with 5,000-7,000 ppm TDS is considered reasonably safe for livestock, although caution is recommended for pregnant or lactating animals. Water with 7,000-10,000 ppm TDS contains a considerable risk for pregnant, lactating, or young animals, or those under heavy heat stress or water loss. Anything over 10,000 ppm TDS should not be used under any circumstances.

Minerals--High levels of certain minerals can be harmful, while other high levels of minerals might only affect palatability. While not toxic, water with high concentrations of sodium, potassium, calcium, magnesium, iron, chloride, or sulfate might not be as readily consumed by horses. Coleman says horses will usually learn to ignore the taste of chlorination in city water.

In other instances, high concentrations of certain minerals can affect absorption of other minerals in the diet. "There are some areas with high-sodium water," says Coleman. "This water will be very soft and have a high sodium content. You might notice that horses won't eat much salt, since they have met their sodium requirements out of the water. It's hard to predict how much of the minerals horses get from their water."

Thompson says that it's rare to find minerals at a high level. "It's a unique case when you find that water contributes to nutritional problems," he adds.

The "hardness" or "softness" of water refers to the amount of calcium, magnesium, calcium carbonate, iron, zinc, strontium, and manganese in the water. The harder the water, the more minerals it contains, says Swinker. While hard water might not be toxic, palatability will be affected, which could affect water intake. In addition, corrosion and clogging of pipes is possible.

Alkalinity, or pH, is another characteristic of water affected by minerals. This is the sum of the concentrations of the alkali metals, which are primarily sodium and potassium, but can also include lithium, rubidium, cesium, and francium. Coleman says that pH is usually not a problem, although horses might not drink water measuring over 8.5. Thompson also notes that water that is too acidic (anything below 6.5) will not be readily consumed. In addition, acidic water can corrode pipes.

If mineral levels are unacceptable, a water conditioner can filter out some of the contaminants, says Thompson.

Bacteria--One serious form of water contamination involves fecal-borne bacteria, says Coleman. A total coliform test checks water levels for bacteria normally found in soil, surface water, and waste material. The most common are Salmonella, Cryptosporidium, and Giardia. Equine and wildlife feces can harbor these bacteria, which can contaminate water sources, especially natural water sources such as ponds and streams. Mature, healthy horses can usually withstand the effects of some bacteria, but Swinker recommends monitoring wildlife disease outbreaks in your area, or in an area in which you might be trail riding.

Chemical Contaminants--Pesticides, herbicides, and fertilizer can present a problem if they contaminate water sources. "Don't overfertilize," warns Thompson. "It all flows to something. Make sure it doesn't flow to a neighbor's pond or well. The same thing goes for pesticides and herbicides."

Swinker says some people think that if one dose of chemical will work, then double that amount will work better, but that attitude can be harmful when it comes to contaminating water supplies.

Coleman recommends limiting the use of chemicals. "That doesn't mean we don't use them," he says. "Don't spray right up to a pond. Consider other management practices." Coleman suggests that mowing or digging plants up by hand might be a feasible alternative to herbicides.

Swinker says, "These beautiful lawns come at an expense. Follow the label. It's on there for a reason." She says a county extension agent or local Environmental Protection Agency (EPA) office can also make recommendations on safe chemical handling and how much to use.

Manure--Manure piles that aren't well-situated can contaminate water sources, resulting in increased levels of nitrate. Coleman recommends controlling runoff from manure piles or from places horses congregate. "Contamination of water sources happens more frequently than people consider," he says.

Thompson advises that manure piles should not be placed within 500-1,000 feet of a water source. Swinker says you should know where leach fields and sewage systems are located on the property, and keep water sources as far away from them as possible. She recalls one person who unintentionally placed a manure pile right over the well head and could not understand where the contamination was coming from.

The Problem with Ponds

It is generally recommended that ponds, streams, and other natural water sources be fenced off from horses. These bodies of water are more susceptible to contamination, and horses which drink from them could be in danger of blue-green algae poisoning. As careful as you might be with your pesticides and fertilizers, sometimes it's not always possible to know what your neighbors are doing. In addition, if a horse is able to get into the pond or stream, he can contaminate the water with dirt, bacteria, and feces.

Coleman says there can be large fluctuations in what is in the water. The biggest problem in ponds is the formation of blue-green algae, which is very toxic to horses and can cause sudden death. Even though there are supplements for horses that contain blue-green algae and claim to be beneficial, Coleman says, "What a horse takes in when he drinks is much more than what he consumes from a small daily amount of supplement." Clinical signs of blue-green algae toxicity include photosensitivity, neurologic problems, bloody diarrhea, labored breathing, liver damage, and convulsions, although these might not be noticed before death occurs. Algae tends to grow during summer and fall in shallow water rich in organic nutrients. "Better to avoid the problem than find out the hard way," reiterates Coleman.

If a pond is used as a water source, Coleman recommends circulating the water with an aeration system to keep it from becoming stagnant. To find out more on aerating a pond, talk to your local extension agent. In addition, treating the water with chemicals such as copper sulfate can prevent or eliminate blue-green algae formation. He recommends checking the label on chemicals very carefully since some can be harmful to aquatic species.

If you want to treat a pond, contact your local EPA office, Army Corp of Engineers office, fish and game commission, or extension agent to find out local regulations.

Swinker says in some states, the Natural Resource Conservation District might provide financial assistance to fence off a natural source of water.

Water Testing

Water testing is fairly inexpensive. Many labs have a standard test, which usually evaluates water for human consumption. This standard test, which generally includes testing for TDS and bacterial counts, costs on average $10-$50. It is possible to test for contaminants beyond the standard test profile, but this will add to the cost. Coleman says if the water is used for human consumption, some health groups won't charge fees. Contact your local extension agent to find out which labs in your area perform water testing.

Important questions to ask include:

  • Are there any previous concerns with water quality in the area?
  • What laboratories perform water testing?
  • What should I test for?

The lab will need to know:

  • What type of source the water is coming from;
  • If the water source is a new or old source;
  • If you are experiencing any problems with the water; and
  • How the water is being supplied to livestock, i.e. hose, bucket, etc.

Once you've gathered the information on where to send your water and what to test for, simply fill up a glass jar with water, seal it, and send it off to the laboratory. For water from a faucet, let it run for several minutes to get a fresh sample once the water is flowing through the system. Also, run the cold water instead of the hot as some people think the mineral content can change when you take a sample of hot water.

Thompson recommends testing well water yearly. He suggests evaluating it at different times of the year, because what happens in the spring, during rainy weather, might be very different from what happens to the water during a dry summer.

Swinker says if there is a certain mineral problem in the area, water might need to be tested more often.

When testing your well, it's important to realize that just because your neighbor's test results came back fine doesn't mean yours will. Your well might be drawing water from a different aquifer (underground water source). Therefore, you still need to test your well, says Swinker.

If your water does test positive for contaminants, your local laboratory or extension agent can offer recommendations on how to improve water quality, such as water softeners, etc.

Containers for Water

There are a variety of ways to provide your horse with water...from water buckets to water tanks of all varieties (plastic, rubber, concrete, etc.), to automatic waterers. Whatever the container, the key is to keep it full of fresh, clean water.

Regarding water tanks, Thompson prefers plastic over metal because they are safer--they don't rust and are less likely to have sharp edges, which could hurt a horse. He says plastic is easy to clean, and it is less likely to produce electrical shocks from malfunctioning heaters than a metal tank.

Coleman recommends checking tanks weekly for insects, small animals, and debris, and they should be cleaned monthly, unless they become dirty sooner than that. Tanks should be scrubbed out and rinsed well. To disinfect, a small amount of bleach can be used then thoroughly rinsed out. "Don't get too carried away, or you might flavor the water," he says. "This would restrict intake and chemicals could build up on the tank."

As an extension specialist, Coleman visits a lot of farms. "People will say their horses aren't drinking or eating, and if you go over to the trough and the water is really disgusting, it's not hard to figure out why they're not drinking," he says.

Large concrete tanks are common in some areas of the country. Thompson cautions against filling one up and not paying attention to it. He recommends cleaning them with a chlorine-based cleaner or a copper sulfate-based product to kill algae. It's important to rinse tanks well if cleaning with chemicals.

Swinker cautions against using barrels or other containers as water tanks that might have once had toxic chemicals in them.

Watering Made Easy

Automatic waterers are a popular option. "They are good to have," says Thompson. "They help farm managers manage the business better. There is less time spent on filling tanks; however, there are down sides. There are always assumptions that waterers are working. You may not know for a day or two that the waterer has stopped working."

Coleman says the biggest disadvantage of automatic waterers is not knowing how much the horse is drinking. "Of course, a lot of people don't pay attention when using buckets," he comments. In addition, if something happens and the waterer leaks, you could find your horse standing in a large puddle the next morning.

Thompson and Coleman offer tips for those looking to buy automatic waterers:

  • Make sure the unit is safe to the horse with no sharp edges;
  • Check for ease of installation;
  • The waterer should be reliable, easy to clean, leak-proof, and should refill quickly;
  • If you live in a colder climate, heaters might be useful;
  • There should be no risk of electric shock;
  • Make sure the unit you buy has the right capacity for the number of horses using it; and
  • Always buy from a reputable company.

Droughts and Flood

If you live in an area prone to droughts or flooding, providing safe water might occasionally be a challenge. Swinker, who previously lived in Colorado, has known people who had to haul in water during a drought. "They work really hard to keep fresh water in front of their animals," she says. If a well is damaged, many well drilling companies will put livestock owners as a priority, since people can always drive to get water for human consumption.

One thing to consider during a drought, Thompson says, is that if the water level drops on a water source during a drought, this will change the composition of the water, concentrating any toxic component, and possibly creating a health challenge.

On the other hand, during a flood, Swinker says the main thing to worry about is the septic system or sewage system not functioning. Coleman says you should watch for changes in water color or odor. When considering whether the water source is still safe, think about pollutants that might have been carried into the source from the flood.

Take-Home Message

No matter what challenges you might face when trying to provide your horse with safe water, consider what might be in the water and whether it could harm your horse. Horses which drink unsafe water, or don't drink an adequate amount of water, could face disastrous results.


For more on water, see the Water/Electrolytes section under Nutrition/Supplements at TheHorse.com.

About the Author

Sarah Evers Conrad

Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.

Stay on top of the most recent Horse Health news with FREE weekly newsletters from TheHorse.com. Learn More