Drinking water for animals is a feedstuff and the most important nutrient. A shortage of water in the
organism quickly leads to a decrease in feed consumption, a reduction in growth, disturbances in
metabolism and finally to death. Biological and chemical ingredients can affect the health of the
animals and the consumer.
The importance of drinking water for the performance and health of the animals is often underestimated. The article addresses the issue of regulating the water balance of the animals, the water
requirements, drinking system technology, water quality and the maintenance and monitoring thereof,
with particular emphasis being placed of broiler chickens. It further deals with the possibility of administering various substances and preparations via drinking water. Knowledge gained at a workshop
on the subject „Water supply in poultry farming – a key factor for health and performance“ is included
in the article. The workshop with international guests was organised by Lohmann Animal Health and
took place in October 2009.
Water is a feedstuff and the most important nutrient for animals (Kamphues et al., 2002; 2007). For
this reason particular attention must be paid to satisfying the animals’ needs, to water line technology
and to the quality of the drinking water. If water is not provided in sufficient quantity and quality this can
lead to drops in performance and even endanger animal health. Water quality is not only significant
for the health of the animals but, in the case of food-supplying animals, also for the protection of
consumers against zoonotic pathogens, e.g. Salmonella spp. and Campylobacter spp. and other
In October 2009 Lohmann Animal Health GmbH & Co. KG held a two-day workshop on the subject
of „Water supply in poultry farming – a key factor for health and performance“. The aim of the workshop was to gather information on the water supply of broiler chickens whereby the knowledge gained
at the workshop should be passed on to others.
Regulating the water balance
Water is needed as a diluent, transport medium and for maintaining internal cell pressure and body
temperature. Water is excreted primarily via urine and faeces but also in the form of steam via the
skin and respiratory tract. In addition to drinking water, water is also available to the animals via
feedstuffs and via metabolic water generated by metabolic processes. Water uptake is triggered off
by the feeling of thirst. Thirst is triggered off by an increased osmolality of body fluids (fig. 1). Dehydration
(exsiccosis) is a hypertensive hypovolumaemia to which an intra-cellular dehydration is connected. The
centre of thirst is situated in the hypothalamus. In the event of shortage of fluid the antidiuretic hormone
Figure 1: Regulating the water supply
(ADH) is released. This causes the kidneys to retain more water and excrete less. In the event of
water excess the release of the hormone ADH and the feeling of thirst are inhibited and thus the
amount of water excreted by the kidneys increased. The concentration of sodium in the blood plasma
in connection with the renin-angiotensin-aldosterone system is also involved in the regulation of water
supply. A reduction in sodium concentration leads to a reduction in the plasma volume. The reninangiotensin-aldosterone system is thus set into operation. It results in an increased resorption of
sodium in the kidneys and an increase in plasma volume.
The water taken up is resorbed in the small intestine via osmotic activity. 70% of the body mass of
broiler chickens is water (Wilson, 2009). Of this around 50 % is located in the intracellular space and
20 % in the extracellular space which is subdivided into intravasal space and extravasal space (fig. 2).
The exchange of water between the fluid spaces is caused by differences in concentration with the aim
of achieving osmotic balance.
Figure 2: Fluid spaces
The animals must be supplied daily with a quantity and quality of water according to their needs
(table 1). Water deficiency results in a reduction in feed uptake and thus in reduced weight gain, to
dehydration / exsiccosis and eventually to death if more than one tenth of water content is lost. Growing
animals take up more water than they excrete (Wilson, 2009).
There is particular correlation between the amount of feed taken up (dry mass) and water consumption
(Langhans et al., 1995). Furthermore, the ambient temperature and feed composition also have an
influence on water consumption. The water requirements of broiler chickens expressed in ml per
animal and day are calculated on the base of the age of the animals multiplied by factor 6 at optimum
ambient temperatures and factor 7 at high temperatures (Wilson, 2009). At temperatures over 20 °C
the water requirements rise by 6 % per °C. Not only the ambient temperature but also the temperature
of the water itself influences water consumption. Water temperature below 5 °C and above 44 °C
leads to lower consumption (Wilson, 2009). Of course the taste of water also influences water
First indicators of an inadequate water supply are a decrease in feed consumption and performance.
The causes can be broken self-drinkers, broken or blocked water lines and insufficient flow rates. A
flow rate of 50 to 80 ml per nipple and minute are required for an adequate water supply – this
corresponds to a handful of water in 10 s (Wilson, 2009).
There is also a correlation between the amount of water taken up and the wetness of the litter. Attention
must be paid that the water supply is not decreased just to prevent the litter material from becoming
Table 1: Drinking water requirements of broiler chickens (KTBL-Heft 83, 2009)
Origin of the drinking water
Drinking water for broiler chickens comes either from the communal network or from the farm’s own
well. Until it is fed into the farm water lines, the water from the communal network is of drinking water
quality which is guaranteed by prescribed monitoring and treatment. The quality of the water from
the farm’s own well corresponds to the quality of groundwater if it is not treated prior to being fed into
the farm and/or drinking system. Based on the results of water analyses the decision must be made
whether any treatment is necessary.
Once the water has been fed into the farm, in particular into the drinking lines, changes can occur
meaning that the quality of the water fed into the system does not correspond to the quality of the
water taken up by the animals. Changes occurring to the water after it has been fed into the water
lines of the farm can have a number of reasons, e.g. resulting from medication or additives being
added to the water or due to contamination of the drinking system following maintenance work
Drinking water system
The first part of the drinking water system is the connection to the communal network or to the own
supply system (farm’s own well). This is followed by the pipe to the houses in which the equipment for
water preparation and dosing equipment for the addition of medication is located. From there the
water is directed into the houses where the height-adjustable drinking water lines with nipple drinkers
are installed. There are nipple drinkers with and without drip cup. There should be 1 drinker for every
12 to 15 animals and the distance between the drinkers should not be more than 2 to 3 m (Wilson,
2009). An important factor is the height of the nipple drinkers above the litter which must be adapted
to the size of the animals. Nipple-drinker systems are low-pressure systems. There is a reduction in
pressure from 3 to 0.01 to 0.04 bar (Meyer, 2009). It should be avoided that the water stands for
longer periods in the water lines which happens in the case of low consumption (e.g. after placement)
as this encourages the precipitation of ingredients, the multiplication of bacteria and the formation of
biofilm (Kamphues et al., 2007). Biofilms are ecosystems of microorganisms of different families which
cohabit in an extracellularly formed polysaccharide-protein layer and are thus difficult to combat using
antimicrobial agents (Eecke, 2009; Watkins, 2009).
Even if the water is primarily of good quality there is a danger of contamination of the drinking water
in the event of technical defects in the drinker system. Open drinkers must thus be protected against
contamination. During the continual monitoring of the drinker systems the following aspects must be
observed (Müller and Schlenker, 2007):
Presence of a sufficient number of drinkers
Availability to all animals
Sufficient water pressure, even during peak requirements
Presence of water meters to monitor water consumption
Frost protection in winter
Prevention of contamination in the drinkers
Access to the drinker systems should be possible for the farm workers to carry out function control
Drinking water quality
Water quality is determined by the presence of microorganisms which cause disease and of substances
which are toxic or influence the taste.
There are no legal requirements for the quality of drinking water in animal husbandry such as those
for the quality of drinking water for human consumption. Drinking water for animals in the EU is
incorporated into the term “feedstuffs” (Regulation (EC) no. 178/2002 of the European Commission
and the Council of 28th January 2002). In order to support the objectives in this regulation the Feed
Hygiene Regulation (regulation (EC) no. 183/2005 of the European Commission and the Council dd.
12th January 2005) was enacted. The stipulations laid down therein came into force on 1st January
2006. According to this the drinking water for animals must be of such quality that it is suitable for
the animals concerned. The legislator restricts the legal requirements to general safety requirements.
However, it is advisable to orientate the requirements for animal drinking water to the Drinking Water
Ordinance (2001). Drinking water for animals should be free from pathogens and free from harmful
substances in toxic concentrations and should also have a pleasant smell and taste. Pathogens and
harmful substances do not only affect the health of the animals but also the sanitary harmlessness
of the food produced from them. In addition to a variety of recommendations for drinking water quality
(e.g. Müller and Schlenker, 2007; Eecke, 2009) there is also a framework issued by the Federal
Ministry for Nutrition, Agriculture and Consumer Protection (BMELV, 2007) on the legal evaluation of
water as a feedstuff. The title is “The hygienic quality of drinking water for animal husbandry”
(„Hygienische Qualität von Tränkwasser“).
This requires the microbiological quality of water fed into the system to be free from Salmonella and
Campylobacter and as far as possible free from Escherichia coli. The colony count of aerobic bacteria
is used as the orientation value for measuring microbial contamination (table 2). These orientation
values should not only apply to the water fed into the system, but above all to the water outlets in the
houses. The imprecise indication for Escherichia coli should be interpreted in such a way that not
more than 10 cfu are present in 100 ml water.
The BMELV has issued orientation values for the evaluation of physico-chemical parameters of
drinking water taking food and feed safety into consideration (table 3). Physico-chemical factors can
lead not only to damage to health but also to changes in the taste of water and deposits in the water
pipes which on the one hand promotes the formation of biofilm and on the other hand can result in
the animals taking up an insufficient quantity of water.
Knowledge on the meaning of physico-chemical parameters for the health and performance of broiler
chickens is incomplete. A pH-value of water of below 5.9 should be detrimental to performance; a pH
value over 8 reduces the disinfectant effect of chlorine (Watkins, 2009). High concentrations of minerals
Table 2: Reference values of the Federal Ministry for Nutrition, Agriculture and Consumer
Protection (BMELV, 2007) for the evaluation of the biological quality of drinking
in hard to very hard water (range of hardness III and IV) due to calcium- and magnesium carbonate
and sulphates, nitrates or chlorides lead to precipitations in the water lines and impairment to the
function of the nipple drinkers (Kamphues et al., 2007; Watkins, 2009; Wilson, 2009). Precipitations
on the walls of the pipes not only restrict the lumen, but also promote the colonization of bacteria and
other microorganisms and thus the formation of biofilm. The electrical conductivity is determined by
the concentration of electrolytes. Values above 500 µS/cm are indicators for depositions of sodium,
potassium and chloride (Kamphues et al., 2007). A content of sodium chloride below 1000 mg/l does
not cause any problems. Values exceeding this level reduce feed consumption. Iron promotes bacterial growth. Particularly when using a farm’s own well, the groundwater can be contaminated with
fertilizer and liquid manure containing nitrate and nitrite which can lead to reduced weight gain (Watkins,
2009). Complexing substances in the water can influence the efficacy of medication and vaccines
applied via the drinking water (Kamphues et al., 2007).
Treatment of drinking water
Particularly when using a farm’s own well the treatment of the drinking water can be necessary. The
main treatments are the filtration of the water, softening and reducing the germ count. Cleaning and
disinfection of the water lines to remove deposits (precipitations) and biofilm also belong to water
There are filters which can be backwashed and replacement filters. Filtration is necessary to remove
particles of dirt such as sand and to remove iron and manganese oxide following the oxidation of iron
and manganese (de-ironing, demanganisation). Softening is required less in cold water pipes than
in warm water pipes and is mainly carried out using ion-exchange resin. If the germ count is too high
(in excess of the values shown in table 2) disinfection should be carried out by adding e.g. chlorine
compounds or active oxygen. Only products approved in accordance with the Drinking Water Ordinance
or with feed laws or with the Biocide Regulation (2002) should be used for the purpose (Kamphues et
al., 2009). UV-radiation can also be used for disinfection (Meyer, 2009).
Table 3: Reference values of the Federal Ministry for Nutrition, Agriculture and Consumer
Protection (BMELV, 2007) for the evaluation of the physico-chemical quality of
A particular problem is the prevention and removal of deposits, air pockets and biofilms in the water
lines. The lines should be flushed up to three times a week with 1.5 to 3 bar pressure, whereby automatic equipment is available for this purpose (Meyer, 2009; Wilson, 2009). Thorough cleaning and
disinfection by flushing and/or rinsing the water lines which have been emptied of drinking water and
are open at the end must take place during the service period as preparation for placement with new
Monitoring drinking water quality
If the water is taken from the public network the quality of the drinking water is only guaranteed up
to the point where the water is fed into the farm (house installation). If wells are available in an animal
production unit solely for providing drinking water for the animals, monitoring of water quality is not
prescribed. Thus, on using farm’s own wells there is a danger of contaminating the flock with
microorganisms and harmful substances. It is thus recommended that well water be analysed at least
once a year prior to feeding it into the farm system. Both drinking water from the public network and
water from the farm’s own well can become contaminated in the water lines of the farm or house,
e.g. due to open supply tanks, due to the addition of medication and vaccines and by the nipple
drinkers. Water can stagnate in the water lines during the service period thus leading to high bacterial
counts and biofilm formation particular at high temperatures. Biofilms can come loose and contaminate
the water with huge amounts of microorganisms, which can also include pathogens. Biofilms, however,
can also secrete metabolic products which have a negative effect on the smell and taste of the drinking
water. It is therefore important to differentiate between the quality of the drinking water fed into the
supply system and the quality of the water taken up by the animals.
The quality of the drinking water at the end of the drinker lines in the house should be determined
once or twice a year. In case of strong deviation from the drinking water quality, appropriate samples
should be taken to clarify whether the contamination is being caused in the farm and at what points,
or whether it is being brought into the farm from the farm’s own well. An inspection of the microbiological
quality of the drinking water should also be carried out following cleaning and disinfection of the drinker
During sampling care must be taken that the results are not falsified due to incorrect sampling. Before
taking a sample the water must run for 5 minutes. A min. of 250 ml is needed for microbiological
analyses, whereby the sample should be sterile if at all possible (flame the tap) and filled into a sterile
bottle to prevent any secondary contamination of the water. To clarify deviations in drinking water
quality or to check the cleaning and disinfection of the drinker system the sampling, place of sampling
and time of sampling must be adapted to the matter concerned. For chemical analyses 2 l of water must
be brought cooled to the laboratory as quickly as possible and kept in the refrigerator until the analysis
is carried out. The analysis should take place within 6 hours if possible.
Various test instruments are available for on-site inspection of the quality of drinking water for human
and animal consumption.
Administration of substances via drinking water
In 2009 BMELV published a guideline on the oral application of veterinary drugs for productive livestock via feed or drinking water. Upon each treatment of food-producing animals the efficacy of the use
of veterinary drugs, the prevention of undesired side-effects, user safety, food safety, consumer protection, animal welfare and the prevention of spreading antibiotic resistance must be taken into consideration when making the decision. The veterinarian must ascertain that the oral application of the
required dose can be ensured for each animal. For administration via drinking water only those drugs
may be used which are approved for this type of application. The pyhsico-chemical properties of the
water must be taken into consideration (e.g. water hardness, pH-value, iron- and calcium content).
In order to prevent any impairment to the drugs and in particular to live vaccines certain demands
must be made on the quality of the drinking water – drinking water suitable for human consumption
should be used. The entry of unused medicated water into the environment must be prevented to
avoid any risks of resistance. The dosing apparatus must be in technically good order. The veterinarian must provide the livestock owner with written instructions on the administration of oral drugs.
Vaccines, antibiotics, minerals, vitamins, amino acids, phytopreparations and organic acids can be
administered via water. By acidifying the drinking water Thorp (2009) achieved improved weight gain
and lower mortality in broiler chickens. Thorp further reported about similar results following administration of health products containing vitamins, minerals, amino acids, glucose, organic acids and
herbal substances via drinking water. The administration of vitamin C is said to reduce heat-induced
stress during catching.
Biozidverordnung (2002): Verordnung über die Zulassung von Biozidprodukten und sonstige chemikalienrechtliche Verfahren
zu Biozid-Produkten und Biozid-Wirkstoffen (Biozid-Zulassungs-verordnung-ChemBiozid ZulV), BGBl I 2002, 2514-2524.
BMELV (2007): Hygienische Qualität von Tränkwasser. Orientierungsrahmen zur futtermittel-rechtlichen Beurteilung.
BMELV (2009): Leitfaden des BMELV vom 19. Juni 2009 über die orale Anwendung von Tierarznei-mitteln im Nutztierbereich
über das Futter oder das Trinkwasser.
van Eecke, J. (2009): Biofilm in water systems of poultry houses. Lohmann Animal Health, workshop „Water supply in
poultry farming – a key factor for health and performance“, Cuxhaven, 20-21 October 2009.
Kamphues, H. and I. Schulz, (2002): Praxisrelevante Aspekte der Wasserversorgung von Labor- und Nutztieren. Übers.
Tierernährung, 30, 65-107.
Kamphues, J., R. Böhm, G. Flachowsky, M. Lahrssen-Wiederholt, U. Meyer and H. Schenkel (2007): Empfehlungen zur
hygienischen Beurteilung von Tränkwasser für lebensmittel-liefernde Tiere unter Berücksichtigung der gegebenen
rechtlichen Bedingungen. Landbauforschung Völkenrode, 57, 255-272.
KTBL-Heft 83 (2009): Wasserversorgung in der Geflügelhaltung. Kuratorium für Technik und Bauwesen in der Landwirtschaft.
Langhans, W., R. Rossi and E. Schürrer (1995): Relationship between feed and water intake in ruminants: digestion,
metabolism, growth and resorption. Proc. Soc. Nutr. Physiol. 3, 199-216.
Meyer, W. (2009): Water systems technology for poultry. Lohmann Animal Health, workshop „Water supply in poultry farming
– a key factor for health and performance“.
Müller, W. and G. Schlenker (2007): Kompendium der Tierhygiene. 3. Auflage, Lehmanns Media, Berlin.
Seemann, G. (2009): Water supply under extreme hygiene requirements. Lohmann Animal Health workshop „Water supply
in poultry farming – a key factor for health and performance“.
Thorp, B. (2009): Administration of substances via drinking water systems. Lohmann Animal Health, workshop „Water
supply in poultry farming – a key factor for health and performance“.
TrinkwV (2001): Verordnung über die Qualität von Wasser für den menschlichen Verbrauch vom 21. Mai 2001
(Trinkwasserverordnung-TrinkwV) , BGBl I 2001, 959 –969.
Verordnung (EG) Nr. 178/2002 zur Festlegung der allgemeinen Grundsätze und Anforderungen des Lebensmittelrechts,
zur Errichtung der Europäischen Behörde für Lebensmittelsicherheit und zur Festlegung von Verfahren zur
Lebensmittelsicherheit vom 28. Januar 2002. Amtsblatt der Europäischen Gemeinschaft: Rechtsvorschriften 2002 (L31)
Verordnung (EG) Nr. 183/2005 des Europäischen Parlaments und des Rates vom 12. Januar 2005 mit Vorschriften zur
Futterhygiene. Amtsblatt der Europäischen Gemeinschaft: Rechtsvorschriften 2005 (L 35) vom 8.2.2002.
Watkins, S. (2009): Water quality in poultry farming. Lohmann Animal Health, workshop „Water supply in poultry farming –
a key factor for health and performance“.
Wilson, M. (2009): Water management in broilers. Lohmann Animal Health, workshop „Water supply in poultry farming –
a key factor for health and performance“.