Water: the forgotten nutrient in pigs

Page last updated: Tuesday, 15 January 2019 - 8:55am

Water is the most important nutrient for pigs. When we think of nutrients we often only think about pig feed: carbohydrates, fats, proteins, minerals and vitamins. However, without water, pigs will only survive for a short time. As we move into the warmer months of the year it is important to ensure that your piggery’s water system is prepared for the heat of summer.

The importance of water for pigs

For good growth and production, pigs require access to good quality drinking water. Water plays an important role in body processes:

  • regulating body temperature
  • transporting nutrients around the body
  • removing toxins and helps with filtration
  • aiding digestion
  • lubricating and protecting the body’s organs.

Water consumption by pigs

At birth, a piglet’s body is 80% water, compared to 50% in a finisher. Pigs need to maintain these levels by consuming water in their feed or by drinking water. It has been reported that for finisher pigs when ambient temperature increases from 10°C to 25°C water consumption is increased from 2.2 to 4.2 litres per day (L/day). This is a significant increase in the volume of water being consumed and therefore the water systems and drinkers need to be able to meet this demand. Table 1 provides an overview of the volume of water consumed by different classes of pigs on a daily basis.

Table 1 The daily water requirements for pigs vary according to their age
Age of pig Daily water requirements
Lactating sow 24-45L/day
Dry sow and boar 12-15L/day
Finisher 9-12L/day
Grower 5-7L/day
Weaner 3-5L/day

Drinking systems for pigs

There are a variety of drinker systems available that suit different production systems and classes of pigs. Sows benefit from high flow drinkers that produce at least 2L of water a minute, allowing sows to drink large volumes of water in shorter time periods. A lactating sow will take 12-23 minutes in total to consume her daily requirement for water from a drinker with a flow rate of 2L/minute. She will do this over several sessions. Lactating sows have a higher requirement for water because they are producing milk which is approximately 80% water. Water consumption is particularly important in the first five days after farrowing. Sows, and therefore piglets, benefit from having easy access to water from a drinker that provides a flow rate that is neither too low or too high as this will discourage the sows from drinking (see Table 2).

Table 2 Recommended flow rates for nipple drinkers pigs according to their age

Age of pig

Flow rate Maximum pressure (kilopascals/kPa)
Lactating sow 2L/minute No limit (avoid wastage)
Dry sows and boars 1L/minute

No limit (avoid wastage)





Weaner 0.5L/minute 85-105

As ambient temperatures increase, sows feel the heat and newly farrowed sows can become lazy and forget or refuse to stand and drink. Sows that do not drink will have a reduced feed intake, will lose body condition and will produce less milk for the piglets. During warm days, ‘lazy’ sows should be encouraged to stand up and drink. It is also important to ensure that the temperature of the water coming out of the drinkers is suitable as pigs do not like to drink water that is above 20°C.

The height of drinkers is also important and should be about 50 millimetres (mm) above the shoulder of the smallest pig in the pen. Ideally, this means that drinkers should be at about snout level or just above the backline of the pig. This is important so that all pigs have access to the drinkers. On the other hand, drinkers should not be too low to the ground to avoid breakage.

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Water quality — what should it be?

The source of water will often determine its quality and suitability for pigs. Scheme water, dam water or bore water all have different benefits.

Annual water test

It is recommended that you test the quality of your water annually. Knowing what is in your water is important in case you need to medicate your water supply. Regular testing will also alert you to any changes that occur to your water quality or suitability. The best time to test is before the break of season, when water concentrates are at their highest level. Water testing will assess turbidity, colour, odour, total dissolved solids, water pH and hardness.


Turbidity is the cloudiness of the water. It is often due to silt or clay being suspended in the water and is usually not a problem to pigs. However, water that scores greater than five nephelometric turbidity units (NTU) should have additional chemical and microbiological (bacterial) analysis.


Tinting of the water is usually due to the particles in the water. In Western Australia this is often related to iron oxide. This is usually not a concern as other parameters give a better assessment of water quality. High levels of iron in the water can reduce the effectiveness of the water soluble antibiotic apramycin. Therefore if this is a medication you may be required to use, it may be important to test the iron concentration in the water on your farm.


Odour should not be present with water. If there is an odour it may indicate the presence of bacterial contamination or organic compounds such as sulphur. The bacterial content of water can be a source of disease to your herd. This is a particular risk for surface sourced water, although ground water can also contain pathogens.

Total dissolved solids (TDS)

This is a measure of the total levels of bicarbonates, chlorine, sulphate, sodium, calcium and magnesium in the water. In general TDS below 1000 is ideal for pigs, while TDS between 1000-3000 is suitable. However, if weaners are suddenly introduced to this water it may cause a transient diarrhoea for a few days. If there is no alternate water source, water containing 3000-5000 TDS can be used cautiously but salt levels in feed should ideally be discussed with your nutritionist or feed supplier.

Water pH

This is the measure of the acidity or alkalinity of water. Water will be safe if it is in the range 6.5–8.5. It is important to know the pH of your water in case you ever need to water medicate as pH affects the dissolvability of some medications.


This is the level of calcium and magnesium in the water. Hardness does not affect animal health but it can lead to an accumulation of scale in water delivery, treatment and cooling equipment, causing nipple drinkers and filters to block up. Very hard water measures greater than 180 milligrams per litre (mg/L) and soft water is less than 60mg/L.

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Hot pigs need cooling

Use a cooling system when ambient temperatures are above the optimal temperature for the pig (see Table 3). Water is an essential part of many cooling systems. Ambient temperatures above the optimal temperature range can compromise the pigs and they can quickly overheat if unable to expel their excess heat.  Pigs do not sweat and so rely on the addition of water (spray/drip cooling) and air movement (wind/fans) to allow evaporative cooling.

Cooling will only be as effective as the surface area of skin that is wetted (that is, spray cooling is more effective than drip cooling).

Table 3 Ideal ambient temperature ranges for all ages of pigs.

Age of pig

Ideal temperature
Lactating sows


Dry sows and boars










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It’s getting hot, now what?

Run through the following checklist:

  • Pre-summer maintenance of all the cooling systems on the farm – replace broken sprinklers, repair any leaks and ensure hoses are flushed of any dirt or foreign material.
  • Repair any broken drinkers and ensure that there are enough drinkers for the number of pigs per pen. Heat stressed pigs drink more, increasing the likelihood of damage and breakage.
  • Secure and seal all water tanks from contamination by rodents and birds. Rodents and birds can be a source of bacterial contamination, or worse; a breach of your farm biosecurity (don’t risk introducing influenza into your herd).
  • Set drinker flow rates appropriate for the age of the pigs (see Table 2). This should be checked and maintained on a weekly basis. Use a 500ml container and measure the volume of water collected from a drinker in 30 seconds.
  • Clean out trough and bowl drinkers on a regular basis – at least weekly.
  • Bury any exposed water pipes under at least 600mm of soil. Pipes heat up quickly in summer and hot water will stop the pigs drinking.
  • Test your water for pH, total dissolved solids and bacteria annually – use a special sample bottle with a preservative for bacterial culture (talk to your vet about effectively collecting suitable samples).
  • Service your water pumps and your backup pump and generator – be ready for any emergencies.

Key points to remember

  • Provide a minimum of two drinkers per pen, with a recommended one drinker per 10-15 pigs.
  • Check water flow – if a pig drinks less than it needs, it will also eat less and grow more slowly as a result. If a pig or group of pigs are not eating much, check that the water is on and the flow rate is within guidelines.
  • Pigs cannot sweat – use cooling or sprinkler systems to help pigs stay cool.


If you discover that the water supply has been turned off or the pigs have run out of water, talk to your vet immediately. They will assist you in treating and managing pigs that have had water deprivation or developed salt toxicity.

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Authored by Susan Dawson, Veterinarian, Portec.