The ration is balanced down to the gram, forage is analyzed, and herd performance is monitored daily. But what about water? In a dairy operation, it sometimes takes a back seat, even though a lactating cow can drink several tens of liters every day.

The available quantity matters, of course. But water quality, taste, temperature, the flow rate of the troughs, and their accessibility can also play a role in the animals' consumption. So, can the water your cows drink really affect their milk production? The answer is more nuanced than a simple yes or no.

Why does a dairy cow drink so much water?

Water is an essential element of a dairy cow's ration. It is involved in digestion, nutrient transport, waste elimination, and body temperature regulation. It becomes particularly important during lactation, as milk itself is composed almost entirely of water.

Requirements are therefore not fixed. They depend on the animal's weight, milk production, the amount of dry matter ingested, the composition of the ration, and climatic conditions.

A review published in the Journal of Dairy Science reports that a lactating cow weighing 582 kg, consuming 18.3 kg of dry matter and producing 28 kg of milk per day, had an estimated free water intake of about 75 liters per day. High-producing cows can reach about 100 liters per day.

The link works both ways: the more milk a cow produces, the more its water needs increase. A meta-analysis cited in the same journal estimated a free water intake of about 2.7 liters per liter of milk produced in Holstein cows averaging 31 liters of milk per day.

These figures remain orders of magnitude and not universal goals. A cow does not necessarily have to drink exactly 75 or 100 liters to be correctly watered. A moist ration already covers part of its water requirements, while the outside temperature, salt, or protein in the ration can significantly alter its consumption.

What must be remembered is simpler: water is not a secondary element of a dairy cow's ration. When its availability or consumption changes, nutrition and performance can also be affected.

Water quality and milk production: is there really a link?

One must be cautious with this question. Observing a drop in production at the same time as a water issue is not enough to prove that the water is responsible. A variation in milk production can have many causes: ration, herd health, stage of lactation, heat stress, comfort, forage quality, or even management practices.

On the other hand, scientific literature clearly shows that access to water and water consumption are linked to the performance of dairy cattle.

A systematic review on drinking frequency analyzed 16 experiments conducted on dairy cows. In the majority of trials, access to water limited to one or two daily periods was associated with a decrease in water intake compared to free or almost free access. The authors also observed a more modest decrease in milk production.

This result does not mean that an additional liter of water mechanically produces a specific amount of milk. Rather, it shows that a cow must be able to drink enough and easily to express its feeding behavior and performance normally.

Water quality then intervenes indirectly. Water with an unusual taste or odor, high mineralization, or certain compounds in high concentrations can reduce its palatability. If the animals drink less, dry matter intake can also be affected in certain situations.

The question to ask is therefore not just “is my water potable?”, but rather: “do my cows have permanent access to suitable water that is sufficiently available and that they drink willingly?”

Which water parameters should be monitored in dairy farming?

Perfectly transparent water can have a very different composition from one borehole to another. Conversely, discoloration or sediment can sometimes immediately reveal a problem. Observation is useful, but it does not replace analysis.

Several parameters may deserve special attention in dairy farming:

• microbiological quality;
• total dissolved solids and salinity;
• sulfates and sulfur;
• nitrates and nitrites;
• iron and manganese;
• certain chemical contaminants depending on the farm's environment;
• the taste, odor, and temperature of the water.

Iron is a good example. A high concentration can alter the taste of the water and cause deposits in pipes and equipment. Manganese can also lead to characteristic deposits and affect palatability when present in significant quantities.

Sulfates, nitrates, and total dissolved solids must also be interpreted with care. Their impact depends on their concentration, the ration, the age of the animals, and other substances present. This is why an isolated analysis result must be interpreted within the global context of the farm.

Microbiology also deserves to be monitored, especially when the water comes from a borehole, well, or private source. But analysis at the source does not always tell the whole story. Water that is correct at the borehole can be degraded further along the line by poorly maintained storage, pipes, or soiled troughs.

To delve deeper into these various parameters beyond just dairy farming, our article Why is quality water important on a farm? reviews the main water-related issues in agriculture.

In hot weather, water becomes even more strategic

You have probably already noticed it on your farm: as soon as temperatures rise, animal behavior changes. Cows seek to dissipate more heat and their water needs increase.

A meta-analysis published in 2026 in the Journal of Dairy Science grouped 17 studies dedicated to the water consumption of lactating Holstein cows exposed to heat stress. On average, cows subjected to heat consumed about 10 liters more water per day compared to animals kept in thermoneutral conditions.

Researchers also observed a relationship between the temperature-humidity index, or THI, and consumption. In their analysis, each additional point of THI was associated with an average increase of about 1.5 liters of water consumed per day. The authors emphasize, however, a strong variability between studies: these values should therefore be used as trends and not as a rule applicable to every farm.

This increase in requirements changes the way equipment is approached. It is not enough for the total volume of water to be theoretically available over 24 hours. It is also necessary that several animals can drink at the moment they feel the need.

Cattle can drink quickly. A scientific review reports that Holsteins can occasionally reach a consumption flow rate of up to 24 liters per minute. An undersized trough, insufficient flow, or too much competition around the watering point can therefore become limiting when the entire herd tries to drink at the same time.

In summer, checking the flow rates, cleanliness, and accessibility of troughs becomes as important as monitoring the quantity of water available at the source.

How do I know if my farm's water is a problem?

There is no single symptom that allows one to immediately conclude that there is a water quality problem. A drop in milk production is certainly not enough.

On the other hand, several observations may justify taking a closer look at watering: water consumption that decreases without an obvious explanation, animals that hesitate in front of certain troughs, differences in traffic between watering points, or the appearance of unusual tastes, odors, coloration, or deposits.

Start with the installation itself. Are the troughs clean? Is their filling fast enough? Are they easily accessible to subordinate animals as well as dominant ones? Is the pressure identical in the different buildings? Do the pipes show signs of deposits?

Next, look at the resource. Municipal water, borehole water, and well water do not necessarily present the same risks or the same variability. With a private resource, a laboratory analysis makes it possible to know its composition precisely rather than relying on its appearance.

When possible, measuring the herd's actual consumption also provides valuable information. A dedicated meter allows you to track its evolution over time and more easily identify an unusual break. However, this data must always be put into perspective with temperature, ration, production, and herd size.

If an anomaly is detected, the goal is not to treat the water at random. You must first identify the parameter at fault. A microbiological issue, excess iron, or high mineralization do not necessarily require the same treatment.

How can I improve the quality of water distributed to cows?

The first step is often the simplest: maintain the watering system. Regular cleaning of tanks, checking pipes, monitoring flow rates, and removing areas that promote stagnation can already prevent water degradation between the source and the animal.

When analysis reveals a problem related to the resource itself, a treatment solution can then be considered. The choice imperatively depends on the identified parameters. There is no universal filter capable of optimally responding to all water compositions.

The FiltraLife Agricultural Solution has been developed for farms to treat water directly on-site. It operates without chemicals and reduces contaminants targeted by its filtration system as well as certain tastes and odors.

The goal is not to promise that filtration will automatically lead to an increase in milk production. Such a claim would ignore all the other factors that determine a herd's performance. The benefit is rather to master an additional parameter of the farm: the quality of the water distributed to the animals.

On a farm where ration, comfort, and health are already monitored with precision, analyzing water therefore helps complete the diagnosis. And when several tens of liters pass through each cow every day, this parameter at least deserves to be known.

Frequently Asked Questions

How many liters of water does a dairy cow drink per day?
Consumption varies greatly depending on milk production, ration, weight, and temperature. A lactating cow can drink around 75 liters per day under certain conditions, while high-producing animals can approach or exceed 100 liters.

Can bad water lower milk production?
Water that is unpalatable, available in insufficient quantity, or has certain problematic parameters can affect water intake and potentially performance. However, a drop in milk alone is never enough to conclude that water is the cause.

Should I analyze the water from a borehole used for cattle?
An analysis makes it possible to precisely know the composition of a private resource and to identify any parameters requiring special attention. The frequency and relevant analyses depend in particular on the resource and the context of the farm.

Why do my cows drink more in summer?
Water consumption increases when animals are exposed to heat. A meta-analysis published in 2026 estimates an average increase of about 10 liters per day in lactating Holsteins subjected to heat stress.

Does filtering water automatically increase milk production?
No. Production depends on many factors. Filtration can help act on certain water quality parameters, but it does not guarantee an increase in milk production on its own.

Water quality should therefore not be considered a miracle cure for producing more milk. It is part of a whole. But when a cow can drink several tens of liters per day and its needs increase further with its production and heat, checking what is actually reaching its troughs is far from a detail.

Sources

• Jensen M.B., Vestergaard M. – Invited review: Freedom from thirst—Do dairy cows and calves have sufficient access to drinking water? Journal of Dairy Science, 2021.
• Singh A.K., Bhakat C., Singh P. – A review on water intake in dairy cattle: associated factors, management practices, and corresponding effects. Tropical Animal Health and Production, 2022.
• Williams L.R. et al. – Drinking frequency effects on the performance of cattle: a systematic review. Journal of Animal Physiology and Animal Nutrition, 2017.
• Zoroaster A. et al. – Effects of heat stress on water intake in Holstein dairy cows: A systematic review and meta-analysis. Journal of Dairy Science, 2026.