York County Cooperative Extension -

Water plays an important role in milk production, temperature control, and body functions for dairy cattle. Cows may consume 4.5 to 5 pounds of water, from drinking and feed, per pound of milk produced (NDPC-30, 1990). Providing the opportunity for dairy cows to consume a relatively large quantity of clean, fresh water is essential. Body functions of water include: transport of nutrients and other compounds to and from body cells; aid in digestion and metabolism of nutrients; elimination of waste materials (urine, feces, and respiration) and excess heat (perspiration) from the body; maintaining a proper fluid and ion balance in the body; and provide the developing fetus with a fluid environment (Linn, 1991). Water also makes up approximately 87 percent of the milk secreted by the cow (Grant, 1993).

Drinking water satisfies 80 to 90 percent of the dairy cow’s total water needs (Ishler, 1998). Therefore, it is logical to assume that plenty good quality drinking water be conveniently located in areas where cows spend most of their time, and offered from a watering units that allow the cows to drink water easily. The water system must be designed to deliver water to each station at the proper rate and keep up with peak demand. Each water station should also be easy to clean and cleaned regularly.

This paper will investigate the drinking water requirements of lactating dairy cows, desirable water station design features in freestall and tie stall shelters, and drinking water supply design considerations.

Each day dairy cows drink large quantities of water. How much they drink depends on milk production, average dry matter content of the feed, stage of lactation, and ambient temperature (CIGR, 1994). A number of equations have been developed to estimate how much water lactating dairy cows consume. In most equations dry matter intake and milk production play a dominant role in estimating water intake.

The modified Kertz Equation (Adams, et al., 1995) estimates total water intake for as follows:

The previous equation determines total water intake from feed and drinking water. Drinking water intake is determined by subtracting the ration water intake from the total water intake as follows:

The equation, developed by Murphy et al. (1983), considers the affect of sodium intake and ambient temperature, as well as milk production and dry matter intake, on drinking water requirements.

Example: Using the given described equations, find the estimated drinking water intake for a 1,400 lb (636 kg) Holstein dairy cow, producing 80 lb (36.4 kg) of milk per day (3.7% fat), consuming 53 lb (24 kg) of dry matter in feed with a moisture content of 55%. Sodium intake is approximately 74 g. The average minimum temperature is 60^oF (15.6^oC).

Temperature and humidity has a dramatic affect on water consumption (Linn, 1991). Hot dry conditions increase water losses through evaporation and urination but reduce water through feces (Beede, 1991). High temperatures with high humidity might not increase water consumption as much because of less evaporative water losses from the skin (NAS, 1974). Typically, cattle under heat stress require 1.2 to 2 times more water per day than cattle in the thermal neutral temperature zone (Beede, 1991).

Table 1. Drinking water intake by dairy cattle (adapted from Adams, R.S., et al., 1995)

Size	Age or production	gallons/day²
Holstein calves:	1 month 2 month 3 month 4 month	1.3 to 2.0 1.5 to 2.4 2.1 to 2.8 3.0 to 3.5
Holstein heifers:	5 months 15 to 18 months 18 to 24 months	3.8 to 4.6 5.9 to 7.1 7.3 to 9.6
Dry cows:	Pregnant, (6-9 mo)	7 to 13
Lactating cows³:	30 lb milk/day 50 lb milk/day 80 lb milk/day 100 lb milk/day	18 to 22 23 to 27 30 to 36 35 to 41

³ Cattle under heat stress may require 1.2 to 2 times more water per day (Beede, 1991)

A sudden drop in performance, particularly during hot weather, can indicate inadequate water supply or dirty water. Other indicators that cattle are not consuming adequate amounts of moisture include (Linn, 1991):

When a cow is drinking naturally, its muzzle is inserted approximately 1 to 2 inches into the water with her head inclined at about a 60^o angle, as shown in Figure 1. In this position a cow can drink between 3 to 5 gallons of water per minute. In order for a cow to drink naturally, from either a trough or bowl, a water surface of 0.65 square feet (94 square inches) should be allowed (CIGR, 1994). This is valuable basic information for water station design for dairy cattle. The watering device should allow cows to draw water easily.

Cows spend approximately 6 hours per day eating (12 meals @ 30 minutes each), but only 5 to 10 minutes per day actually drinking water. However, this does not reduce the need for well designed, conveniently located watering stations. Cows seem to have the highest water intake during hours when feed intake is greatest. When given the opportunity, cows tend to alternately consume feed and drink water. Fresh, clean water should be available whenever cows consume feed (Grant, 1993). Cows also seem to readily drink water soon after being milked.

The requirements of the cows should determine the design of the watering stations that serve them. Freestall shelters contain watering stations used by groups of cows; preferably allowing a number of cows at the same time.

At least two watering locations should be provided for groups larger than 10 cows. (Graves, 1995). Multiple water stations help to reduce the affect of dominant cows, since alternative locations are available.

Even though cows spend a relatively short time each day consuming water, they tend to gather near water stations for, especially during hot weather. Therefore, the waterer should be sized to accommodate multiple users at one time. “Rule of thumb” recommendations vary by climate. Midwest Plan Service guidelines suggest a minimum of one waterer location, or 2 feet of accessible trough perimeter for every 15 to 20 cows (Bickert, et al., 1997). This allows space for approximately 5 to 7 percent of the group to drink at the same time. A 100 cow group would require 10 to 14 feet of accessible trough perimeter.

For groups of 200 cows or less, Armstrong (1998) suggests the water stations should accommodate 15 percent of the group at the same time; allowing 2 feet of accessible perimeter per cow. For example, a 100 cow group requires 30 feet of accessible trough perimeter. For groups larger than 200 cows, Armstrong suggests the waterers should accommodate 20 percent of the group at once. This recommendation is based on milking parlor size and performance. More than enough watering space is provided to accommodate cows released from one side of the milking parlor. With 12 to 15 minutes between group changes the thirst of the previous group may be satisfied by the time the next group arrives.

Armstrong’s recommendation is for more arid climates where water loss by evaporation from the skin is higher, and period cows experience heat stress is longer. However, many areas of the United States experience extended periods of hot weather where cows experience heat stress. Therefore, having plenty of drinking water available, and even supplementing it during warm weather is very desirable.

A crossover lane to the feeding area should be provided every 60 to 80 feet to allow better access and more uniform feed consumption along the length of the feeding area (McFarland, 1994). As mentioned earlier, fresh, clean water should be available whenever cows consume feed (Grant, 1993). Crossover lanes provide an excellent and logical location for waterers.

In May 1997, volume meters were installed on three identical trough waterers in a three-row freestall shelter containing 99 stalls. The waterers were located at each end, and in the middle of the freestall area. The number of cows in the shelter ranged from 64 to 85 during the observation period. The objective was to monitor total drinking water intake and observe if the cows showed a preference for any water station(s). After more than a year of observation, the water station in the central crossover typically delivered approximately 35 to 45 percent of the total drinking water.

When located in crossover lanes, a minimum width of 12 feet is needed to allow cows to drink while others pass behind her (Graves, 1995). Figure 2 shows the space required for mature cows around waterers.

The surface around the water station should be firm and provide a confident footing for the cows. The area should slope away from the watering unit approximately 1/2 inch per foot to prevent puddles.

Waterers should be easily accessible to the cows. Barriers that do not allow free access to the waterer are discouraged. Locating the watering units a the feed barrier is not recommended. This reduces available feeding space, may easily contaminate waterers, cause sloppy feeding areas, and make it harder to remove left over feed (Graves, et al., 1997).

The size of the animal using the waterer should determine the height that water is presented. The height of the waterer is measured from the floor to the top edge the cow must reach over to get to the water. The water surface should be approximately 2 to 4 inches below the top edge to avoid excessive spillage and splashing (CIGR, 1994).

One source suggests the top edge of the waterer be 61 percent of the height of the cows withers, from the floor (CIGR, 1994). For Holstein cows this is approximately 33 inches, and 30 inches for Jerseys. Observation indicates this may be the maximum height a cow should reach over to access the water surface.

A height of 24 to 32 inches seems to be reasonable for mature Holstein cows (Graves, et al., 1997). This places the water surface at 20 to 30 inches above floor level, with 2 to 4 inches below the top edge (Figure 3). Reducing these heights 2 to 3 inches may be preferred for Jerseys.

The water depth presented is also important. It should be deep enough to allow the cow to submerge her muzzle 1 to 2 inches into the water and consume as much as she desires without causing her to gulp air (CIGR, 1994). Preferably, the water dispenser should maintain a minimum water depth of 3 inches as the cow is drinking (Graves, et al., 1997).

Relatively shallow water depths of 3 to 8 inches are be preferred since they can offer fresher water and reduced accumulation of debris. However, if the flow rate cannot maintain the desired water depth, then waterer capacity should be increased. Keeping the waterer clean and free of debris is important with all waterers, but more careful attention may be needed where deeper water depths are offered.

Guards, barriers, and steps are used to prevent cows from urinating, defecating, and standing in waterers. These methods can be effective, but should not hinder cows from using the water, or prevent them from drawing water easily.

A step at the base of the waterer is often used to reduce the chance of cows contaminating the water with urine or manure. This is somewhat successful, but in most dairy systems there is an opportunity for caretakers to observe the water stations several times per day for contamination and clean them if needed. A concrete support base which provides a 2” ledge around the perimeter of the waterer will help protect the bottom section from damage.

Some cows will stand with their front feet in a water trough. A guard rail can be placed directly above the edge of the water trough to discourage this behavior. The guard rail should be securely fastened and not restrict access or cause injury to cows. For the trough height discussed earlier, the recommended horizontal rail position is 48 to 60 inches from the floor, and in line with the edge of the waterer. Provide at least 24” of clear opening between the top edge of the waterer and the rail.

Figure 3. Cross section of concrete or polyethylene water trough (Graves, et al., 1997).

In freestall shelters, the cows share the waterers provided in the group. There are several styles of watering units available and used in freestall shelters. Watering units that present a generous surface and volume of water, that one or more cows can easily drink from at the same time are preferred. Water must be delivered by a non-backsiphoning valve. The valves should be protected to prevent damage or malfunction by the cattle. An outlet should be provided to allow easy, and complete, removal of water and sediment when cleaning. The drain plug should be easy for the caretaker use, but protected to prevent accidental removal by cows.

Freezing of the exposed valves and water lines are a concern in some climates. Some producers open a small diameter (1/8 to 1/4 inch) overflow tube during cold weather to allow the inlet valve to continuously deliver a small flow of water and reduce the chance of freezing. Consideration should be given to proper drainage of overflow water to prevent ice build up and slippery conditions around the water station. A number of producers in South-central Pennsylvania have noted that freezing waterers are rarely a problem due to the regular drinking activity of the cows. Other producers have reported they simply shut off and drain waterers at locations vulnerable to freezing during extremely cold weather. Increased activity at the remaining water stations, further reduces the chance of freezing.

Water troughs are commonly made of metal, concrete, or plastic. The water depth is commonly 3 to 8 inches, so the water offered stays relatively fresh and clean. When water flow to the unit is adequate, troughs are preferred in dairy shelters since more than one cow can drink at the same time (Figure 3). Water cleanliness is relatively easy to observe, and most can be emptied and cleaned easily.

Some manufactures offer a water trough unit with an insulated compartment that provides the valve protection from freezing and damage by the cows. Regular inspection and cleaning of the valve compartment is reduces sediment build up and water contamination.

Vats, or tanks, often provide large quantities of water since water depth and the height of the tank are very similar. This type of waterer is often selected when the recovery rate of the water system is slow, or the water supply is sporadic, such as a plate cooler. They are often made of concrete, and due to the water depth, observation of sediment build up and condition of the water can be less obvious. The outlet, should allow both water and sediments to drain completely for cleaning

A popular watering device in freestall shelters is the tip tank (Figure 4). These units are typically fabricated from metal and hold 75 or more gallons of water. The water level is maintained by a non-backsiphoning float valve. The tank is mounted on an off-center pivot that keeps the tank relatively stable in the upright watering position. The tank may be overturned for cleaning, which may result in more frequent cleaning. However, regular scrubbing of the tank is still necessary.

Energy-free watering units use an insulated enclosure, and the relatively stable temperature of the earth below the frost line to prevent freezing. A float, such as a ball or disc, seals the access opening when not in use. A non-backsiphoning float valve within the unit maintains the water level. Cows must push the floating device aside in order to drink. These units greatly reduce the chance of freezing, however, their design may also discourage cows from consuming as much water as they could. The covers are effective in preventing freezing during cold weather, but should be removed during warm weather to allow more convenient access. Observation of water quality and sediment build up is not as obvious, therefore, the caretaker must make an extra effort to monitor their condition and clean them regularly.

Energy-free waterers should be considered in areas where a limited number of cows have access, and where the waterer must be installed along a north or west wall of a shelter in an area that experiences long periods of very cold weather.

In 1991, water consumption was observed in a six-row dairy shelter with 716 freestalls. The shelter contained 880 cows in four groups. Each group had access to an energy free waterer (with two openings and ball closures) in the two end crossovers, and a “tub” waterer (14 feet long) in the central crossover of each group. After approximately 14 months, the cows had consumed about 7 million gallon of water. Approximately 5 million gallons were consumed from the open tubs, and 2 million gallons were consumed from the energy-free waterers (Weeks, 1998).

Heated waterers have been used in cold climates for decades. Typically an electric, or gas, heating unit with an adjustable thermostat keeps the drinking water from freezing. Although the surface area of the water is much less than a trough, access to the water is usually better than energy free units, which may improve intake. The water depth is usually adequate and they are relatively easy to clean. Concerns with these units include the additional cost of providing electric service to each waterer, the cost operation during cold weather, and the danger of electrical malfunctions near water.

Since the cows are tethered to each stall, the number of watering units is determined by the reach allowed the cows and the stall structure surrounding them. Typically one waterer is provided for every two stalls in a row, and shared between occupants. Time demand for the waterer usually is not a problem in this situation, but dominance can be. When pairs of tied cows that shared a water bowl were studied, the dominant cow drank and yielded significantly more milk than the submissive cow. The only way to be certain in all situations that cows have access to sufficient amounts of water is to have one water bowl per cow (Andersson, 1984). An advantage of tie stall shelter design may be that water and feed are offered in the same area, and water is within reach at all times when cows are in their stalls.

Whether to place the waterer over the feed alley or the stall bed usually depends on whether the producer prefers a wet feed alley or wet stall beds since cows occasionally splash water and valves malfunction.

With unobstructed access to the water unit, it seems logical to follow the same height recommendations as used in freestall shelters. However, the stall structure often presents an obstacle that interferes with free access to the waterer. Stall dividers, feed manger dividers, tie rails, and even electric “trainers” can make access difficult and uncomfortable for the cow. If the stall structure does not allow each cow easy access, the barrier should be removed, or a waterer per stall should be considered.

The space around the and above the watering device should allow the cow to insert her muzzle into the waterer, activate the valve (if necessary), and drink. This dimension is determined by the size of the cow’s head. The length from muzzle to poll, for mature Holstein cows, is typically 20 to 22 inches. Therefore, providing this amount of room between the top of the waterer and the bottom of any obstruction directly above it is recommended.

In some applications that use a single tie rail at the front of the stall, the waterer is placed at the same height as the tie rail. Tie rail height is typically 36 to 38 inches, and may be too high for cows to drink easily; especially if they need to turn their heads, and activate a valve. The question to ask is not “can they drink?”, but “can they drink easily?”.

Some producers have lowered the waterers to provide easier access. For waterers placed over the feed table, the bottom of the divider was removed so the waterer can be placed high enough to allow a push broom, used to clean the feed table, to pass under it. Although drinking water intake data was not taken, the producers reported that the cows seem to use the waterers more frequently, and splashing is reduced.

Whether the cow must activate a valve or not, the water level should be maintained to allow the cow to drink a her preferred rate without gulping air. As discussed earlier, a minimum of 3 inches is recommended. Two objectives of tie stall shelter waterer design are to reduce splashing and make cleaning easier. These are important features, but often result in smaller water unit sizes (diameter and depth), making it difficult for the cows to drink freely. The water supply also needs to provide a flow rate that can keep up with peak demand. The water level should be at least 1 inch below the top edge reduce splashing and overflow.

Water bowls are typically 8 to 10 inches in diameter and 4 to 6 inches deep. Some companies now offer an oblong water bowl which provides more convenient access for a shared bowl. Common materials used for water bowls are cast iron, galvanized steel, stainless steel, nylon, and plastic. A cow activated non-backsiphoning valve is typically used to deliver water to the bowl on demand. Paddles activated by the end or side of the cow’s muzzle are common, but tend to make cleaning slightly more difficult. Also, the hinge points tend to wear rapidly, so regular maintenance and repair is necessary. Push-button valves, about 1.5” in diameter, activated by side of the cow’s muzzle are also popular. Pressure reducing valves in the water supply line are necessary to allow the cows to operate the valves easily.

Water bowls with cow activated valves have been used successfully for many years. However, many producers become frustrated with the amount of maintenance required to keep them cleaned and operating properly.

Water bowls that do not require the cow to deliver water to the bowl have become quite popular in recent years. An “automatic” non-backsiphoning valve helps maintain the desired water level, perhaps allowing the cow to drink more easily.

Some bowl designs hold a reserve volume of water (in some cases up to 3 gallons) readily available to the cows. This is an advantage if the water system is not be able to keep up with peak demand, but it also provides a place for sediment to collect and must be cleaned regularly.

A relatively new tie stall watering system uses a 6-inch diameter PVC loop as a reservoir, located directly above the stall area. A 1-inch diameter flexible hose connects a float valve, secured to the water bowl, to the reservoir. The volume of water stored in the bowl at any given time is relatively small, however, the flow rate and volume supplied by the overhead reservoir can easily keep up with demand. The overhead reservoir holds approximately 1.4 gallons per lineal foot. If the water supply to the reservoir is unable to keep up with demand, air inlet valves located at the top of the PVC pipe allow water to flow into the water bowls needing water. As demand it reduced, the overhead pipe is refilled. An air outlet valve allows the reservoir loop to fill completely.

The overhead reservoir provides plenty of water volume before the bowl, so the bowl size is relatively small. One manufacturer uses a fabricated stainless steel bowl with a water surface of about 8 inches square, and 5.5 inches deep with a nominal water depth of 3.5 inches. Another supplier offers a round bowl, made of polyethylene, approximately 9 inches in diameter, and 6 inches deep with a nominal water depth of 3 inches. Due to the limited water surface area, careful attention must be given to allow easy access for the cows. Careful consideration should also be given to the support of overhead reservoir. The water stored in the loop of 6 inch diameter PVC pipe in a typical 60 stall shelter may weigh over 3,300 pounds.

Although the bowls in these systems are sometimes advertised as “self-cleaning”, producers find they still need to remove sediment and scrub them regularly. As with anything mechanical, failure can occur. Dirt particles can keep the valve from shutting off completely and overflow. A shut off valve above each water bowl makes maintenance and cleaning more convenient.

“Gravity” water systems offer some advantages that are attractive to tie stall dairy producers. A single valve can supply multiple waterers, a large volume of water is offered at each location, and the risk of freezing water lines is greatly reduced if the supply line is located under the stall bed.

Most systems use a 3 to 4-inch diameter PVC supply line located directly under the waterers, and beneath the stall bed or feed manger. Vertical risers, typically 1.5 to 3-inch diameter black plastic or PVC pipe connect the supply line to the bottom of the water reservoir. Some water reservoirs are made of 10-inch diameter PVC pipe with formed concrete bottoms. Water bowls with a large capacity are also available commercially. A vertical upstand at one end contains a non-backsiphoning float valve that determines the water level in all the reservoirs it serves. A drain line located at the opposite end, allows the system to drain completely to remove water and sediment. Tie stall barns that are sloped from one end to the other require multiple systems to allow easy access for the cows.

A concern with this system is that it must be cleaned often. Feedstuffs fall into the supply line and, left unattended, can contaminate the water supply. Some producers complain of “musty” or “stale” smelling water which cows are hesitant to drink, especially in systems that use a single valve to supply several reservoirs. Also, the supply line is not easily accessible and can be difficult to scrub clean. The general rule-of-thumb for the cleaning of these systems seems to be to clean them well before they appear to need it.

Water troughs have also recently gained popularity in tie stall barns. An open trough is fastened near the tie rail. Many troughs being used are made of stainless steel, measure about 8 inches at the top, 6 inches at the bottom, and about 5 inches deep. The water depth is about 3 to 4 inches. An automatic non-backsiphoning float valve is mounted at one end, and protected to prevent damage by the cows. An overflow and/or clean out opening is located at the other end. This system offers a generous surface area and volume of water to the cows, and can be cleaned quite easily.

Proper placement of the trough is important. It should be low enough to allow easy access for drinking, but high enough to allow cows to reach the feed table below. Troughs must be installed level, therefore, tie stall barns that slope from one end to the other require multiple units.

Another variation of the trough watering system in tie stall barns uses an 8 inch diameter PVC pipe with holes cut into the top that allow cows access to the water. A valve assembly and outlet similar to the metal trough is used in this version as well. Careful attention should be given to the water depth since the bottom is curved and adequate capacity may not be available.

Producers using these systems report improved water intake and immediate milk production increases. However, it should be noted the condition of their previous watering system probably warranted improvement or replacement.

Cleaning is convenient with troughs, but must be done often. Feed and sediment accumulate rather quickly. Since water flow is directed toward the end opposite in supply valve, this end of the trough gets dirty quickly.

One thing that all cattle watering units have in common is that they must be cleaned, and cleaned often. Disease causing organisms, such as E.coli 0157:H7 bacteria, may be spread on dairy farms by contaminated waterers, not bad water (Hoard’s Dairyman, 1998).

Feed intake, milk production, and animal health all depend heavily on drinking water intake so the producer must accept the responsibility of keeping the watering devices clean and in good repair. Accumulation of sediment, such as feed, bedding, and manure can contaminate the water, and should be removed at least once per day. Weekly, or as needed, the watering device should be drained and scrubbed using a diluted chlorine solution.

Far too often the task of cleaning the watering units is not performed as regularly as needed. Some manufacturers even advertise “self-cleaning” waterers. These systems claim that a combination of small reservoir and high flow rate put the sediments in suspension allowing the cows to draw them in with the water. Relying totally on this cleaning feature is not good management practice since other materials such as sand, sawdust, bird droppings and manure may make up a portion of the sediment present. Producers find also, that the waterers still need to be scrubbed cleaned regularly to insure good water quality and animal acceptance.

All of the details and factors concerning the design of a water supply system cannot be covered in this section. However, it is important to cover some details that affect the delivery of water to the watering locations. References such as the “Private Water Systems Handbook” (MWPS-14) provide detailed information on water system design. Plumbing suppliers are another good source of information.

The volume of water delivered to a water station is not determined by the pump alone. Valves, fittings, pipe size, pipe material, and elevation head all develop resistance that reduces flow rate to the watering device(s). The challenge in water system design is to size the lines large enough to provide adequate flow, but small enough to prevent large pressure drops that may result in system failure. The following procedure is recommended for selecting pipe size (MWPS-14):

6. If pump size or pressure settings are unusually large, select larger piping to

The pipes and the distribution system should meet or exceed the minimum requirements of the National Plumbing Code and local codes.

Connections should be installed to prevent the backsiphoning of polluted water back into the water system. Disease causing organisms may get into a system through back flow, or back siphoning, from livestock waterers, toilets, sinks, and flooded pump pits. Steps must be taken to prevent this from occurring.

All cross connections and interconnections between potable and non-potable water systems should be eliminated (MWPS-14).

Backsiphoning is caused by a lack of pressure in the system causing the fixture to drain back into the piping. The valves used in livestock watering units must be non-backsiphoning. When the waterer is full, the air gap at least twice the diameter of the outlet between the water surface and the outlet. (MWPS-14).

In many cases, the well pump capacity is unable to keep up with peak demand of the watering system, therefore, a reservoir is needed to allow the system to respond to (and satisfy) demand. Reservoirs can also eliminate the relatively short and frequent pumping cycles that occur in a system without much reserve.

Water may be pumped to a reservoir over a longer period of time, then removed as needed. The size of the reservoir depends of the demand on the system, and capacity of the well pump. Some reservoirs are sized to hold the amount of water the well pump can supply in 8 or more hours at a time. A second pump sends water through the main and branch water lines as needed.

Using the watering unit as a reservoir is not highly recommended due to the potential of contamination that may occur if the tank is not drained regularly for cleaning and sediment removal.

Buried tanks usually create less of an obstacle than above ground storage tanks, and may provide more uniform water temperature. Reservoirs made from concrete or polyethylene are preferred. They should be covered and designed to prevent contamination from surface runoff.

The information presented here only considers the drinking water supplied to the shelter for the cows. Additional water volume and flow rates required for other uses, such as cleaning and supplemental cooling, must also be considered in the total design of the system

The type of watering unit and shelter style can influence on the design of the supply line. In freestall and loose housing, cows must travel some distance and “share” the waterers with a number of other cows. In tie stall housing, the watering unit is readily accessible and usually only shared with one other cow. The management of each shelter design may influence of the drinking behavior of the cows.

If a cow can drink water at 3 to 5 gallons per minute (gpm), then the recovery rate should satisfy this demand. If a watering unit allows three cows to draw water at the same time, then the recovery rate should be 9 to 15 gpm at that location. If three similar watering units are available to the group at different locations, then the total demand for that group is 27 to 45 gpm.

At peak times, if space for 15 percent of a group of 100 cows is available, then cows may consume 45 to 75 gpm.

In a tie stall shelter, the flow rate to each bowl should match the cow’s water intake rate (3 to 5 gpm). The highest demand in a stall barn is typically when cows return to the barn as a group during hot weather. At these time, all of the cows may want to drink, but only half can due to the number of watering units available. In a 60 tie stall shelter, with 30 water units, the peak demand on the system could be as much as 90 to 100 gpm at times. Water delivery to the bowl may be reduced further due to the size of the water supply line, and the “shape” of the system. Most tie stall watering systems cannot keep up with the demand, and the cows Bringing a water supply line in near the middle of the stall rows and branching in either direction may improve the water flow rate to individual watering units.

Galvanized pipe is common in above ground applications in dairy systems. A galvanized water line often doubles as the tie rail in stall barns. It will withstand high water pressures, but joints must be threaded, and therefore more difficult and time consuming to make.

Table 3. Recommended sizes for outdoor uses-Schedule 40 thermoplastic pipe (MWPS-14).

Flexible plastic pipe is common for underground piping because of installation ease and economy. It is available in coils of 100 feet or more, joints are easy to make, corrosive soils do not create a problem, and it is very resistant to inside pipe corrosion. Plastic pipe with at least a 80 pounds per square inch (psi) rating is recommended (MWPS-14).

Table 3 can be used as a starting point to determine the required pipe diameter for Schedule 40 thermoplastic pipe. This can be used as a guideline for the pipe sizes that may be required. The pipe suggested pipe sizes are noted for various flow rate (vertical axis) and pipe length (horizontal axis) combinations. Larger pipe diameters have lower friction loss values per unit of length. Losses are also caused by valves and fittings. Table 4 shows these losses, in equivalent length, for various valves and fittings.

Table 4. Pipe fittings and equipment; equivalent lengths of straight pipe (MWPS-14).

Type Fitting & Application	Pipe & Ftg Material	Equivalent Length, feet Nominal Size of Fitting & Pipe
Type Fitting & Application	Pipe & Ftg Material	1/2”	3/4”	1”	1-1/4”	1-1/2”	2”	2-1/2”
Insert coupling	Plastic	3	3	3	3	3	3	3
90o standard elbow	Steel	2	3	3	4	4	5	6
	Plastic	4	5	6	7	8	9	10
Standard tee, turn	Steel	4	5	6	8	9	11	14
flow thru	Plastic	7	8	9	12	13	17	20
Gate or ball valve	Steel	2	3	4	5	6	7	8
Swing check valve	Steel	4	5	7	9	11	13	16
Globe valve		15	20	25	35	45	55	65

The study of water use and intake is interesting. Several sources can be found concerning the estimated water intake a various stages of a dairy cow’s life and lactation. However, it seems there have been relatively few controlled studies concerning water consumption and drinking behavior from different watering unit types, their location, size, and so on. Further investigation of this subject is needed.

Water is an essential element in the production of quality milk. Dairy system designers need to pay close attention to the needs of the cows when developing drinking water supply and delivery systems for dairy cattle. The number, placement, and design of the watering units must be determined by the cows “natural” drinking behavior and preferences. The ability to provide a plentiful quantity of clean, fresh water is paramount.

The design of the water delivery system should also allow easy observation and attention by the caretakers. Regular cleaning to remove sediments and contamination is necessary. The caretakers must take responsibility of the quality of water offered to the cows.

Drinking water should not limit the production and profit potential of a modern dairy enterprise.

Adams, R.S., et al. 1995. “Calculating drinking water intake for lactating cows”. Dairy Reference Manual (NRAES-63). Ithaca, NY: Northeast Regional Agricultural Engineering Service.

Andersson, M.. 1984. “Drinking water supply to housed dairy cows”. Svergies Lantbruksuniversitet Dissertation Report 130. Uppsala, Sweden. In Albright, J. L. & C. W. Arave. 1997. The Behavior of Cattle. 1st edn CAB International, Oxon, UK and New York, NY. 306 pages

Armstrong, D.V.. 1998. Personal communication. Extension Dairy Specialist and Research Scientist, University of Arizona, Tucson, Arizona.

Beede, D.K.. 1991. “Water for dairy cattle: quality and cooling effects”. Proceedings from the Southwest Nutrition and Management Conference. University of Arizona.

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