In difficult economic times, dairy producers look for ways to do more with less. In the case of clean drinking water, however, the rule is to do more with more. Water intake may be the bottleneck preventing more efficient production on your dairy.

Seymour will
Ruminant Technical Manager / Novus International

Water is the most essential nutrient, yet its role in dairy cattle nutrition, physiology and health is often taken for granted. Efficient production of milkfat, protein and solids depends directly on adequate intake of water which is the other 87.5 pounds in 100 pounds of milk. A cow cannot make milk without plenty of clean, fresh water.

The average 1,500-pound cow’s body contains about 1,000 pounds (or 120 gallons of water). With an average total water intake of 35 gallons per day, this pool of water is turning over once every four days. Water output comes in the form of milk (33 percent), manure (33 percent), urine (20 percent) and the combination of perspiration and expiration from the lungs or panting (15 percent).

These outputs correspond to the essential processes of digestion, metabolism, milk synthesis and regulation of body temperature and electrolyte balance.

About 3 pounds of water are required to make a pound of milk. A 1,000-cow dairy producing 85 pounds per cow with a goal of shipping 90 pounds per cow will need to supply an additional 1,800 gallons of drinking water per day to reach this goal. Water intake is, not surprisingly, highly correlated with dry matter intake.


Cows drink most of their water during daylight hours, and the majority of this occurs in the first hour after milking. Therefore, peak demand for water can be a bottleneck on the dairy depending on water space, tank capacities and the flow or refill rate of waterers. In general, one or more of these criteria typically seem to be lacking.

Poor location of water troughs is a common problem. Cows exhibit dominant-subordinate behavior around water just as they do at the feedbunk, in stalls and in the milking parlor (see Photos). Water access is limited by water tanks located in narrow crossover alleys or other restricted areas.

Water bottle neck

Kansas State researchers have shown that cows prefer water stations located closer to feed and return alleys and those areas with greater space and freedom of movement. (Table 1)

Percentage of water consumed at various locations within pen on a dary with two water troughs per crossove ralley

Hot weather and heat stress increase water requirements by up to 50 percent compared to thermoneutral conditions. The water molecule is uniquely able to absorb and transfer heat from both inside and outside the body and is critical for heat stress relief. A cow producing 100 pounds of milk requires 4 to 5 gallons more drinking water per day at 80ºF than at 60ºF. Part of the summer slump on milk yield may be due to limited water supply.

Many dairies today are overstocked relative to designed capacity. Overstocking applies to water supply as much as it does to stalls, feedbunks and holding areas. Hot weather only intensifies any shortfall in water supply.

The simplest remedy is to add water space and access; in the holding area, the return alley or elsewhere in the pens, preferably within 50 feet of the feedbunk. This assumes adequate water pressure and flow to keep the water tanks replenished during peak use and adequate space around the water troughs to allow cows to drink comfortably.

Benchmark RegionA study of commercial dairy farms in Ontario found that an increase in 1 inch of linear water space per cow was associated with 2 pounds more milk production.

Additionally, water intake is affected by diet moisture content and by intake of certain minerals, principally the electrolytes: sodium, potassium and chloride. Fresh cows and cows in early lactation are especially sensitive to the supply of these ions. These ions must be kept in balance with each other relative to requirements.

In milking rations, especially those high in corn silage, the supply of dietary potassium may be limiting milk production, especially during hot weather. Research has shown that supplemental potassium with adequate access to salt supports better performance under heat stress conditions. Water intake likely plays a role in this response. Many nutritionists now balance lactating cow diets for a positive dietary cation-anion difference balance (higher potassium and sodium relative to chloride), especially during hot weather.

Water quality is a concern, and a yearly water test is a worthwhile investment. Several forage testing labs offer complete water quality testing services, including proper sampling containers and reference ranges for water constituents. Michigan State researchers report that excess levels of free iron, sulfates, chlorides and total dissolved solids are among the most common water quality issues observed.

In some instances, nitrates and/or coliform bacterial counts may be above concern levels. In these cases, the well may need to be sanitized or changes made in drainage around the wellhead to prevent contamination.

The most common water quality problem observed on dairies is cleanliness (or lack thereof) of water tanks, troughs, bowls or stations. Clean water tanks are the first and most important quality issue. Problems can be easily and cheaply remedied with a combination of bleach and elbow grease.

Guidelines for water space and supply in freestall dairies

1. Water space

  • 3 1/2 inches per cow with 3- to 6-inch water depth

  • One water tank or station per 15 to 20 cows

  • Provide two-thirds of a square foot of water surface area per cow.

  • Cows preferred water in tanks 24 inches versus 12 inches in height.

2. Water location

  • Locate water near milking parlor exit and feed

  • Locate water in shade

  • Locate water in nonrestricted areas, i.e., wider crossovers, return alley

3. Water flow capacity

  • 3 to 5 gallons per minute at the water tank or station

  • Flow may be restricted by pipe diameter, condition, pump or well capacity

  • Cows prefer cool to warm drinking water (65ºF to 80ºF).