Water is one of the most consumed nutrients by dairy cows and yet it is often overlooked. Lactating dairy cows can drink anywhere from 20 to 40+ gallons a day depending on the weather and how much milk they are producing. Water access and quality directly impact milk production, health, and overall performance. The reason is simple enough when you look at the composition of milk itself. Typically, we focus on components like fat and protein because they drive milk price, but milk itself is about 85-90% water. Water is also helpful in promoting normal rumen function, helping with proper digestion and nutrient uptake, as well as temperature regulation. Given these important roles, water intake becomes a key management consideration.

Water Requirements

According to The University of Nebraska-Lincoln Extension guide on Water Quality and Requirements for Dairy Cattle, "Even a small limitation in water intake will decrease dry matter intake by 1-2 pounds daily, which could limit peak milk production by 2-5 pounds. Lactating dairy cows require 4.5-5 pounds of water per pound of milk produced. This equates to roughly one-half gallon of water for every pound of milk secreted. As an example, a cow producing 100 pounds of milk daily could consume as much as 50 gallons of water. Remember that daily water intake comes from both drinking and moisture (water) in the consumed ration. For example, if a ration contains 40 percent moisture, it contains 40 percent water. That means a cow eating 80 pounds of this ration daily would be consuming 32 pounds of water (80 pounds ?-- 40 percent moisture = 32 pounds of moisture, or water)."  They also published a very useful table on the expected daily water intake for the different classes of dairy cattle which I have included below.

 

Livestock class

Age or Production

Gallons/day2

Calves

1 month

1.3 to 2.0

2 months

1.5 to 2.4

3 months

2.1 to 2.8

4 months

3.0 to 3.5

Heifers

5 months

3.8 to 4.6

15 to 18 months

5.9 to 7.1

18 to 24 months

7.3 to 9.6

Holstein cows

Lactating

18.0 to 40.0

Dry cows

Pregnant, 6 to 9 months

9.0 to 13.0

 

 

 

Table 1. Drinking water requirements of dairy cattle.1

1. Table published by Kononoff & Clark, 2017. Water Quality and Requirements for Dairy Cattle. University of Nebraska Extension and adapted from: Swistock, B. 2016. Interpreting Drinking Water Tests for Dairy Cows. Pennsylvania State University. https://extensionpubs.unl.edu/publication/g2292/na/html/view

2. Higher levels of water intake apply for an all-hay ration (greater than or equal to 80 percent dry matter).

 

Water Availability & Access

As a dairy cow behavior enthusiast, I enjoy spending time observing cows and their routines. One pattern I frequently noticed was that cows often drank immediately after being milked, usually alongside feed intake. Fortunately, this observation isn't just something I noticed on my own and research in the dairy literature strongly supports it. These are important considerations when thinking about your watering infrastructure. Pennsylvania State Extension published the following infrastructure recommendations:

• 2 to 4 inches of perimeter space per cow
• Optimal water tank height ranges from 24 to 32 inches
• Water depth should be a minimum of 3 inches
• At least 2 watering locations per pen to prevent dominant cows from guarding the waterer
• Provide enough space at the waterer so that 20% of the cows in a group can drink at once
• Water tank located within 50 feet of the feed bunk or at every crossover in a freestall barn
• Water should be immediately accessible after returning from milking
• Heifers should have access to one appropriately sized water space per 20 animals

They emphasized that these recommendations also apply to cows on pasture, although there are additional considerations when it comes to water access in pasture systems.

Pasture Considerations

Water placement is incredibly important when you are grazing cows. Table 2 below shows how the distance cows have to travel for fresh water can have a dramatic impact on their forage consumption. Research from the University of Missouri Forage Systems Research Center states that the goal would be to have water access within 900 feet which can be difficult to achieve in a lot of systems. From my experience, many farmers have had success working with their local Soil and Water offices to get water to all parts of their pastures.

Table 2. How distance from water affects grazing.1

Distance from Water (Miles)

% of Forage Consumed

0-0.5

50

0.5-1

38

1-1.5

26

1.5-2

17

2-2.5

12

1. Table published in book "Managing Pasture" by Dale Stricker (2019) and adapted from: R. K. Lyons and R. V. Machen. "Livestock Grazing Distribution: Considerations and Management." Texas Agrilife Extension Bulletin L-5409 2001

 

Water Quality

              Cows are very sensitive to water contamination and will drink less if their water contains manure or even certain dissolved minerals. The Farmers Assuring Responsible Management (F.A.R.M.) 2023 Animal Care Standards Reference Manual states that, "water that is significantly soiled and/or contaminated with feces, dirt, mud, or manure, and/or has algae growing would be considered too dirty. For calves, milk contaminates fresh drinking water." These are the baseline welfare standards for farms participating in the F.A.R.M. program. While visibly dirty water is important to avoid, it is also important to be aware of water quality issues that are not visible to the human eye. University of Nebraska-Lincoln recommends testing your cow's water supply yearly for coliforms, pH, nitrate and nitrites, and total bacteria. They created a handy reference seen in Table 3 which can be helpful when interpreting your water test results.

 

Table 3: Analysis of water supplies1

Item

Average

Expected2

Possible Cattle Problems

pH

7.0

6.8-7.5

Under 5.5; over 9

(ppm)

(ppm)

Dissolved solids

368

500 or less

Over 3,000

Total alkalinity

141

0-400

Over 5,000

Sulfate

36

0-250

Over 2,000

Fluoride

0.23

0-1.2

Over 2.4

Calcium

60.4

0-43

Over 500

Magnesium

13.9

0-29

Over 125

Iron

0.8

0-0.3

Over 0.3 (taste)

Manganese

0.3

0-0.05

Over 0.5 (taste)

Copper

0.1

0-0.6

Over 0.6 to 1.0

Arsenic

—

0.05

Over 0.20

Cadmium

—

0-0.01

Over 0.05

Mercury

—

0-0.005

Over 0.01

Lead

—

0-0.05

Over 0.10

Nitrate as NO3

33.8

0-10

Over 100

1. Table published by Kononoff & Clark, 2017. Water Quality and Requirements for Dairy Cattle. University of Nebraska Extension and adapted from: Swistock, B. 2016. Interpreting Drinking Water Tests for Dairy Cows. Pennsylvania State University.

2. Based primarily on criteria for good water for human use.

 

To sum it up, good water management goes a long way. Make it a routine to clean waterers, check that they are refilling quickly, and test water quality from time to time. Keep an eye on your cows as well. It's not always easy to slow down when there's so much to do, but those moments when you can step away and just watch cows being cows are often the best ones, not only for the brief reprieve from the hustle and bustle of the day, but also because paying attention to these details can make a noticeable difference in cow health and milk production.

 

Resources:

https://extensionpubs.unl.edu/publication/g2292/na/html/view

https://extension.psu.edu/the-value-of-water

 "Managing Pasture" by Dale Stricker (2019)