Water System Design Considerations for Modern Dairies

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Introduction

Site selection for modern dairy production facilities is dependent on numerous criteria. One of these criteria is an adequate water supply. The facility must have the potential to develop or obtain a water supply of sufficient quantity and quality to serve the anticipated present and future production needs (Hoehne et al., 1994). Minimum water requirements for meeting the intake water needs of lactat­ing cows, milk parlor usage, and other needs of a function­ing dairy seem to range from 40 to 50 gallons per cow per day (gal/cow/dy) (Allen et al., 1974; Bailey et al., 1993; Beede, 1992; MWPS-7, 1997). Water usage can increase to 100 gal/cow/dy if a wash pen is used. The following figures suggest that if a wash pen is not used, 1 acre-foot of water is annually required per 15 cows. Therefore, it is critical that adequate water rights be obtained during the initial phase of planning, expanding, or remodeling a dairy. Lack of planning can mean that, even though adequate water rights are obtained, the water supply cannot be delivered in quantities necessary to meet the dairy demands. Poor planning can also result in not having adequate water supplies to address heat abatement issues.

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Water Supply

Ground water is probably the water source of choice if it is of sufficient quantity and quality (Hoehne et al., 1994).

Wells

A secondary well provides a backup in the event of failure of the primary well. If a single well is used, a storage tank with a minimum of a two- to three-day water supply is recommended.

Purchased Water

If a choice is made to purchase water, Hoehne et al. (1994) recommended not using water supplied by rural water districts as a modern dairy's primary water source. Dairies purchasing water from a rural water district must also have a storage tank to handle outages. These dairies also must work with the rural water district to ensure that their system can handle the demands of the dairy facility.

Surface Water

Hoehne et al. (1994) recommended surface water supplies have at least a two-year storage capacity. Reservoirs must be large enough to store the water anticipated to be used plus losses due to evaporation, seepage, and other inherent losses. Surface water supplies will probably require treatment prior to usage. Minimum treatments would control bacteria and reduce sediment.

Demand versus Usage

Two water issues – demand and usage – should be addressed during the planning of a dairy.

The demand is maximum water used during a given time period and is normally measured in gallons per minute (gpm). The water system must be able to meet the maximum amount of water used during a single 1- to 5-minute interval during the day.

Seasonal demands should also be considered. A water supply may be ad­equate during the winter but insufficient during the summer when heat abatement equipment is utilized. On a modern dairy, the maximum demand generally will occur during the summer when:

  • most of the cows are drinking water,
  • sprinkler or mister may be on, and
  • milk parlor and equipment lines are cleaned.

The second factor to consider is usage. Usage is the total amount of water used during a day. It is important to consider all present water requirements as well as future water needs. Modern dairies need to consider the drinking water requirements of heifers, dry cows, and lactating cows; cleaning the milk parlor; usage at hospital facilities; water requirements of restrooms; truck wash water, etc.

In the housing area, approximately 69% of the water is used for drinking with the remainder being used for sprinkler systems. However, the minimum demand by the watering troughs for a 1,000-cow dairy is 30 gpm, while the sprinkler demand is 125 gpm, assuming all of the cows are cooled simultaneously.

Types of Water Lines

A water line or pipe transfers water between two points, and other factors beyond just the demand and usage must be considered. Equivalent pipe length, pipe diameter, pipe location, and piping losses must be consid­ered. There are three basic types of water lines to consider; however, each water line must be able to supply the demand requirements. These include the main, distribu­tion, and branch water lines.

The main line carries the water from the well or storage tank into a dairy complex. Proper sizing of the main pipe is critical because it must be able to deliver the demand of the entire dairy. Water distribution problems arise when future expansion is planned but the main water line is sized only to meet the current needs. Unless a second water line is going to be installed, the main water line must initially be sized to meet the demands of the final dairy size.

Distribution lines carry water from a main line junction to specific buildings or areas such as a freestall housing area, milk parlor, or office complex. It is recommended to size the distribution lines in freestall housing areas based on the demands of the watering and sprinkler systems. Generally, this water line is undersized because adding sprinklers for cow cooling is an afterthought. Therefore, in the future when a cooling system is added, even though the initial plan was never to install one, the water lines cannot meet the demands of the sprinkler and watering system. The de­mand to meet the needs of the sprinkler system is three to four times greater than the demand of the watering troughs.

The third type line is the branch line which carries water from the distribution line to the end use. Examples include the waterers, sprinklers, plate coolers, wash machine, or milk parlor platform. Normally, these water lines are probably adequately sized. The difficulty occurs when a branch line becomes a distribution line, for example, when a branch line to a watering trough is tapped into for the sprinkler system. Another difficulty occurs when a branch line needs to be added, but installation requires placement of lines under concrete. Often in this scenario, the line is added above ground and then lack of mainte­nance, draining lines that may freeze, become a problem.

Pipe Losses

Water pipes need to be able to supply water to the end usage based on the peak flow rates. The plumbing system must be able to overcome losses incurred as water moves through the pipes. Pressure losses occur due to pipe friction, elevation differences between the pump source and point of use, and velocity losses due to water move­ment. Friction losses are due to water flowing through pipes, fittings, and valves. Often friction losses through fittings and valves are based on the equivalent feet of straight pipe (MWPS-30). Table 1 shows different fittings and their equivalent straight pipe length. The water velocity and inside surface roughness affect the friction losses. To reduce excess friction losses, normally the system is designed to limit pipe velocity to 5 fps or less. Water hammering will result when velocities exceed 5 fps.

Table 2 shows the flow rate in gpm through various size pipes based on 4, 5, and 7.5 fps flow velocities. It is recom­mended to use the column showing 4 fps for the main and distribution lines. Branch lines can be sized based on the 5 fps velocities. Table 2b shows the capacity of different sized pumps based on the total head at which a pump must operate against. Pipes should be selected based on the following guidelines (MWPS-7):

  1. Limit the pressure loss to 5 psi when moving water from the pressure tank to a building (this would be the losses in the main and distri­bution lines);
  2. Limit the pressure losses in the branch lines to less than 5 psi;
  3. Limit the pressure losses in the main line to less than 1 psi per 100 feet of pipe; and
  4. Use a maximum water velocity of 4 fps to prevent water hammering.
Fitting Type Pressure Loss (psi) Equivalent Pipe Length (ft)
Table 1. Effect of friction associated with pipe fittings and valves.
90° long sweep elbow 0.05 14
90° standard elbow 0.8 20
45° elbow  0.03  8
Gate valve, wide open  0.02 5
Gate valve, half open  0.41 130
Flow meter 0.14 32

 

Table 2. Estimated flow rate of various pump capacity operating against different pressure losses.

Pump Size

(horsepower)

Estimated Flow Rate (gpm) Based on Pump Size (hp)
Average Feet of Head
20 40 60 80 100 120
10 1,485 743 495 371 297  
20 2,970 1,485 990 743 594 495
30 4,455 2,228 1,485 1,114 891 743
40 5,940 2,970 1,980 1,485 1,188 990
50 7,425 3,713 2,475 1,856 1,485 1,238
75 11,138 5,569 3,713 2,784 2,228 1,856
100 14,850 7,425 4,950 3,713 2,970 2,475

 

Table 2b. Recommended maximum flow rate through pipe using different flow velocity. Water hammering may occur at velocities greater than 5 fps and require special fittings.

Nominal Pipe Diameter

(inches)
 

Flow Velocity through Pipe

(feet per second)

4 5 7.5
0.5 2 3 5
0.75 6 7 10
1 10 12 20
1.25 15 20 30
1.5 20 30 40
2 40 50 70
2.5 60 80 120
3 90 110 160
4 160 200 300
6 350 440 660
8 630 780 1,200
10 980 1,200 1,800
12 1,400 1,800 2,600
16 2,500 3,100 4,700
24 5,600 7,000 10,500

Water Usage

Water usage on a dairy will vary significantly among dairies. Zuagg (1989) studied five dairies and found water usage varied from 80 to 240 gallons per lactating cow per day. Dairies raising replacement heifers and using calf barns utilized more than 200 gallons per lactating cow per day. Wiersma (Zaugg, 1989) reported water usage on Arizona dairies in 1975 at 91.5 gallons per cow per day. Zuagg (1989) also indicated that the Arizona Department of Water Resources adopted 105 gallons per lactating cow per day and 20 gallons per nonlactating cow per day as the maximum water usages for dairies by the end of 2000. Table 3 summarizes the daily water usage on the five dairies in the Zuagg (1989) study. In South Florida, dairies applied for a consumptive use permit to use 40 gallons per cow per day for drinking and 130 gallons per cow per day for flush water (Bray et al., 1994).

 

Table 3. Summary of daily water usage on five dairies in the southwestern United States (Zaugg, 1989).
Dairy Identification and Milking Frequency
  A(3x) B(3x) C(2x) D(2x) E(3x)
Daily Water Usage
Total Gallons per Lactating Cow* 186 101 95 72 182
Udder Wash per Lactating Cow 93 49 19 24 65
Drinking
Early Lactation 34 31 30 29 35
Late Lactation 27 28     25
Dry Cow 16 13     17
Close-up   16     17
Calves (hutches or barns)   3 2 2 25**
2-6 months   3 4 4 5
7-15 months         10
16-22 months         11
Cooling
Shade Evaporative Cooler   15     16
Shade Misters     4.5    
Fence Line Misters     2.5 1.4  
Holding Pen Sprayer   2 2 2.3  
Exit Sprayer 2.1     0.8  
Parlor Evaporative Cooler 1.4 0.5   0.1 5.4
Parlor
Hot Water 0.8 0.3 0.7 0.8 0.9
Cold Water 5.9 2 1    
Drop Hoses 1.8     2.5 2.1
Wash Hoses 3.3   6   6.5
Vacuum Pump 6.5       5
*Total water usage divided by the number of lactating cows.
*Includes cleaning and sanitizing wire cages, concrete floors, and alleys.

 

Drinking Water Requirements

Lactating milk cows will drink from 30 to 50 gallons of water per day. A summary of daily water requirements for different types of dairy cattle is shown in Table 4. Data collected during the study comparing the impact of dietary fiber (Dado and Allen, 1995) indicate a cow will drink about 1.5 gallons of water per trip to a watering trough at a rate 1.3 gpm. Dado and Allen also found that a cow will spend about 12 to 16 minutes per day drinking water. Their measured free water intakes were lower than most studies. However, using these data, a cow makes about 24 trips per day if she drinks 40 gallons per day and 1.5 gallons per visit. Assum­ing a 12-foot watering trough and 6 cows present, the minimum water flow rate would be 8 gpm. A group of 100 cows spends approximately 40 hours of time per day at watering troughs. Even though cows spend only about 2½% of their time at the water trough, adequate water space recommendations per cow are to provide 2 feet of tank perimeter or one watering space per 15 to 20 cows (MWPS, 1997). Reinemann and Springman (1992) deter­mined the drinking water requirements based on 4.5 to 5 pounds of water per pound of milk. They recommended the peak flow to waterers at 0.5 to 1 gpm per 10 cows. Dairies using a parlor more than 18 hours per day can probably use a peak flow rate of 0.5 gpm per 10 cows, whereas dairies using a parlor less than 12 hours per day should use 1 gpm per 10 cows.

Martin (2000) estimated a peak flow rate for larger dairies based on 10 gpm times the number of waterers in one group plus 10 gpm on all remaining lactating groups. If the facility houses heifers and dry cows, peak flow rates for these groups may be based on daily consumption (gallons) divided by 1,440 minutes per day, to estimate the flow rate (gpm).

Animal Type Water Usage
(gallon/day/head)
Table 4. Estimate of drinking water requirements for different dairy animal types (MWPS, 1999).
Calves (1 to 1.5 gal/100 lb) 6 to 10
Heifers 10 to 15
Dry Cows 20 to 30
Lactating Cows 25 to 50

Wash Pen

The wash pen is a significant user of water on a dairy. Wiersma (1988) indicated 15 to 20 gallons per cow per milking may be used in the wash pen. Zaugg (1991) found on five dairies in Arizona that the wash pen used from 19 to 93 gal/cow/day. The average value was 50 gal/cow/day. The water usage in a wash pen can equal the drinking water requirements. However, the demand will be much higher because a group of cows must be washed in a relatively short period of time.

Milk Equipment and Parlors

Many dairies have reduced water usage in the milk parlor by changing udder prep procedures. Dairies using hand-operated wash hoses or automatic prep systems will utilize between 1 and 4 gallons per cow per milking. Water usage can be reduced to less than half a gallon per day when using low water techniques such as single-service towels. If cow towels are being used, water usage by the wash machine must be considered. Larger amounts of water are required for spray pens. Ludington and Sobel (1992) reported in a case study that hot water usage dropped from 3.4 gallons per cow per day to 0.69 gallons per cow per day when the udder prep procedure was changed from udder washing to dry prepping with pre- and post-dip.

Factors influencing the water usage in cleaning milking systems include pipeline diameter, air injector settling, number of cycles per milking, etc. Automatic clean-in-place systems require from 100 to 300 gallons per milking for large parlors with weigh jars. Milk equipment suppliers should be able to provide an estimate of water requirements for cleaning the type of system being installed.

Water usage for bulk tank cleaning can be estimated by dividing a bulk tank size by 20 (Reinemann and Springman, 1992). The amount of water required is 3 to 5% of the tank volume with automatic washing systems. Water utilized in cleaning the milk equipment and bulk tank is not potable after that use but may be stored and reused for flushing the cow platform and holding pens.

Reinemann and Springman (1992) recommended sizing the water requirements of plate coolers based on 1 to 2 pounds of water per pound of milk. Water usage may be less than 1 to 1 if no attempts are made to control water and milk flow. Spencer (1992) also noted water usage with pre-cooler may be twice as much as the milk produc­tion while obtaining 30 to 50% of the cooling requirements.

Fresh or clean water is required when flushing the parlor platform and holding pen. Water can be recycled from the plate cooler to perform this task. Weeks (1992) reported that about 7.5 gallons of water per cow were required per day for flushing the milk parlor and holding pen. However, the milk parlor was only used less than 8 hours per day. Some data suggest an adequate flush can be obtained using 1.5 gallons per sqare foot per flush. Assuming 30 cows per milk stanchion per milking, with each stanchion being 40 square feet (2.5 feet by 16 feet – rapid exit space included) along with 15 square feet per cow in the holding pen would result in 2.75 gallons per cow per flush or frequency of milking. Therefore, it is recommended for planning that the water requirements for flushing the milk parlor be based on 5 to 7.5 gallons per cow per day. Basing the demand on delivering the water during a 3-minute flush cycle, the water demand can be estimated by multiplying the number of lactating cows by 1 gpm. A 1,000-cow dairy would have a water demand for flushing the platform and holding pen of 1,000 gpm. This demand does not have to be included in the water distri­bution system if recycled water from the milk equipment room is utilized.

Another method to reduce the water demand is to provide a storage tower. In this case, the demand can be based on the available time to fill the tank. If 4 hours are available, the demand reduces from 1,000 to 10 gpm.

Sprinkler Systems

Sprinkler systems are used to wet the cow’s back and can be used in the holding pen and along the feed lane. Bray et al. (1994) reported water usage for low-pressure systems ranging from 18.6 to 56 gallons per cow per day. They reported a study by Montoya (1992) that found 23% of the water was evaporated and 15% of the total water applied evaporated from the cow’s body. This rate of evaporation equaled about 1.1 gallon per cow per hour.

Bray and Bucklin (1995) recommended applying 0.05 inches per cycle when sprinkling cows. This converts to 0.03 gallons per square foot of wetted area. A cow will have about 12 square feet of wet area based on 2 feet along the feed line and 6 feet for cow length. Sprinkler systems generally operate based on 3 minutes on and then 12 minutes off. This will vary among regions and system design. The demand of the sprinkler system can be esti­mated by the number of cows being cooled multiplied by 0.1 gpm/cow. The water usage can be estimated by multiplying the number of cows by 0.3 gal/cow/cycle or 1 to 2 gallons per cow per hour. Therefore, if 1,000 cows are being cooled simultaneously, the demand would be 100 gpm, and the water usage would be 300 gallons.

Table 5 provides a summary of water usage and demand rates for low-pressure sprinkler systems based on length of feed line. Pipe size can be reduced by locating the water line serving the sprinkler system in the middle rather than at one end. Plumbing becomes expensive with trying to meet the water demands on long feed lines due to the increase in pipe size necessary to carry the water demand.

Length of Feed Line (ft) Water Usage per Cycle (gal)* Water Demand (gpm)
Table 5. Estimate of water usage (gallons) and demand (gpm) for a low-pressure system located along a feed line.
100 20 7
200 40 13
400 75 25
600 110 38
800 150 50
1,000 190 62
*Based on wetted distance from feed line of 6 ft and 0.05 inches of water/cycle/square foot and 3 minute on cycle.

Sprinkler systems can be operated either simulta­neously or sequenced. A simultaneous system cools all of the cows at once and places the most demand on a system. The system basically comes on for the set time interval and is off until the next cycle occurs. The 1,000-cow example mentioned earlier has a demand of 100 gpm. A sequenced system results in using controllers to sequence the sprinklers on between different pens. For example, using a four-row, 1,000-cow freestall, the sprin­kler system in each quadrant of the building would come on at different times. This results in significant cost savings because the demand on the water system is reduced from 100 gpm to 25 gpm. The water usage is still 300 gallons, but it can be delivered over a 12-minute interval rather than 3 minutes. Additional controllers are required with sequencing systems, and management must be available to operate these systems. It is much easier to switch from a simultaneous to a sequence system than vice versa. There­fore, initial planning requires careful consideration.

High-pressure systems using misters require different types of planning. Bray et al. (1994) reported high-pressure fog ring systems use between 1.5 to 2 gallons per hour with water usage a function of pressure. For planning purposes, dairies can estimate the water demand of high-pressure systems based on 0.03 gpm per fan. The system demand is based on the total number of fans being installed with misters multiplied by 0.03 gpm/fan. Assuming 1 fan per 5 cows, the system demand for a 1,000-cow dairy would equal 6 gpm. However, in many regions, a sprinkler system is still needed along the feed line to adequately cool cows.

Dairies in the southwestern United States use evapora­tive cooling under shade or cattle shade coolers. Armstrong and Welchert (1994) reported water usage for these systems from 0.2 to 2 gpm. One fan will serve 13 to 15 cows. The daily water usage with a shade cooler can be estimated by multiplying the number of cows times 0.1 gpm times the minutes per day of operation. The water demand can be estimated by multiplying the total number of shade cooler unit fans by 1.5 gpm. Using the 1,000-cow example and 12 hours of operation per day, the daily water usage would equal 72,000 gallons of water, and the demand would be 100 gpm.

Holding pen sprinkler systems should be sized based on providing 0.01 gallons of water per square foot of area (gal/sq.ft.). Table 6 shows the water requirements for different sized holding pens and the required flow rate of the water system. The flow rate is based on a cycle of 3 minutes on and 12 minutes off. The time the sprinkler nozzles are on may be reduced if the udder of the cow is getting wet.

Holding Pen 
Capacity

Typical Pen Size (feet by feet)

Water Required (Gallons/Cycle) Minimum Flow Rate (gpm)*
Table 6. Sprinkler nozzle requirements based on holding pen capacity.
80 24 by 50 40 14
100 32 by 48 50 16
120 32 by 56 60 20
160 32 by 75 80 30
200 32 by 96 100 40
300 32 by 144 150 50
400 32 by 192 200 75
500 32 by 240 250 100
*Flow rate based on a 3-minute on cycle with 12 minutes off.
**Assumes nozzles have an 8-foot spray diameter and 0.5 gpm capacity.

 

  Percent of Lactating Cows  Daily Usage (gal/day) 1,000 Lactating Cows (gal/day) Minimum Well(s) Capacity Based on 20 Hours Pumping   (gal/min)
Table 7. Estimate of daily water requirements and demand for 1,000 lactating cows.
Drinking Water
Lactating Cows 92 40 gal/cow    
Dry Cows 25 30 gal/cow    
Calves/Heifers 115 15 gal/cow    
Sick/Lame Cows 8 30 gal/cow    
Milk Parlor
Plate Cooler   1.5 lb water per lb milk 14,400 12 gpm
Wash Water 100 5 gal/cow 5,000 4 gpm
Flush Water 100 25 gal/cow 25,000 21 gpm
Employees 1 FTE/80 cows 50 gal/employee 600 0.5 gpm
Sprinkler System* 4 cycle/hr 1 gal/cy/cow 96,000 80 gpm
Special Needs
Special Needs Parlor 8 15 gal/cow 1,200 1 gpm
Holding Pen 3x milking 3 gal/cow/milking 9,000 8 gpm
Minimum pumping capacity from the well into a storage tank 185 gpm
*Assumes the times are sequenced such that no more than 4 groups are being sprinkled at a time using a 3-minute on and 12-minute off cycle.

Summary

Modern dairy facilities will use between 50 to 200 gallons of water per cow per day depending on the operation. Proper planning requires obtaining adequate quantities and qualities of water to meet the present and future water requirements. It is important during the planning phase to consider the water demands of the dairy and design accordingly. When in doubt or uncertain, it is better to err by installing larger pipe so that management changes may be made in the future.

Author Information

Joseph G. Martin, Consulting Engineer
Joseph P. Harner, Biological and Agricultural Engineering, Kansas State University
John F. Smith, Animal Sciences and Industry, Kansas State University

References

Allen, J.B., J.F. Beatty, S.P. Crockett and B.L. Arnold. 1974. An analysis of the water usage and waste treatment at a modern dairy. ASAE Paper No. 74-4038. American Society of Agricul­tural Engineers, St. Joseph. MI.

Armstrong, D.V. and W.T. Welchert. 1994. Dairy cattle housing to reduce stress in a hot-arid climate. Proceedings, Third International Dairy Housing Conference: Dairy Systems for the 21st Century. American Society of Agricultural Engineers, St. Joseph. MI. Pp. 598-604.

Bailey, K., M. Bennett, J. Garrett, D. Hardin, J. Hoehne, J. Spain, B. Stevens and J. Zulovich. 1993. Missouri Dairy Plan - The Missouri System of Dairy Production 500 Cow Plan. Unpub­lished Extension Manual. Dairy Focus Team, Commercial Agriculture Program, University of Missouri Extension, Columbia, MO.

Reinemann, D.J. and R. Springman. 1992. Water quality, quantity, and distribution. NRAES-66. Proceedings, National Milking Center Design Conference. Northeast Regional Agricultural Engineering Service, Cornell University, Ithaca, NY.

Spencer, S.B. 1992. Milking cooling and storage equipment. Chap 12. A.J. Bramley, F.H. Dodd, G.A. Mein and J.A. Bramley, eds. Machine Milking and Lactation. Published by Insight Books.

Weeks, S.A. 1992. Cleaning the milk parlor. NRAES-66. Proceed­ings, National Milking Center Design Conference. Northeast Regional Agricultural Engineering Service, Cornell University, Ithaca, NY.

Wiersma, F. 1988. Water requirements for an Arizona dairy. Personal correspondence.

Zaugg, N.L. 1989. Water usage on dairies in the southwestern desert. Unpublished report.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.