Adequate water access is a fundamental welfare requirement for pigs, yet inadequate nipple drinker provision, low water flow rates, and poor water quality cause chronic thirst-related suffering in many commercial systems.
Pigs deprived of adequate water experience thirst, a powerful negative affective state demonstrated through preference testing. Chronic underhydration impairs feed intake, growth, and immune function. Competition for scarce drinkers causes aggression, with subordinate pigs unable to access water during peak demand periods. Salt poisoning (hypernatraemia) can paradoxically result from water deprivation followed by sudden water access. Good water provision requires adequate flow rates, sufficient drinker numbers, and regular quality testing.